UM-3 Pumpkin CubeSat Kit User Manual
Contents
1. Figure 16 Layer 1 and Silkscreen Do Not Scale UM 3 Pumpkin CubeSat Kit User Manual 56 The RTOS that runs in tiny places User Manual Part Numbers Pumpkin i ae Part Number Description Notes 703 00243 Body 1U 10cm tall 703 00244 Body 2U 20cm tall 703 00245 Body 3U 30cm tall 703 00246 Top Cover 703 00247 Bottom Cover 703 00248 Foot Top Helper Spring 703 00249 Foot Top 703 00250 Foot Bottom 705 00193 MSP430 Flight Module for MSP430F 149 705 00194 Development Board general purpose 711 00227 Kit 1U for 10x10x10cm CubeSats 711 00241 Kit 2U for 10x10x20cm CubeSats 711 00242 Kit 3U for 10x10x30cm CubeSats Table 14 Pumpkin CubeSat Kit Major Part Numbers UM 3 Pumpkin CubeSat kit User Manual 57 The RTOS that runs in tiny places Contact Information 58 Pumpkin Contact design MASSIF Contact Pumpkin Web Site design MASSIF Web Site Digi Key Corporation User Manual Andrew Kalman aek pumpkininc com 415 584 6360 Adam Reif massif designmassif com 530 620 6402 http www pumpkininc com http www designmassif com b2. Table 1 Default Jumper Settings for Development Board for MSP430 Flight MCU Plug the Benchtop 5V power supply into JI and verify the following voltages 3 Supplied without a power cord Accepts IEC standard power cords 4 There are several GND test points scattered across the Development Board UM 3 Pumpkin CubeSat Kit User Manual 5 The RTOS that runs in tiny places USB Interface User Manual Signal Location Value Vv 5V TP9 5V VCC TP12 3 3V VCC_MCU TP20 3 3V VCC_232 TP21 3 3V V _232 TP19 gt 5V V _232 TP22 lt 5V 5V_SW TP10 OV RST NMI TP8 3 3V Table 2 Startup Voltages for Development Board for MSP430 Flight MCU Remove the 5V power Install the Flight MCU header board being careful to observe its orientation it only goes one way If the Flight MCU header board has a socket install the Flight MCU now Again observe the correct orientation of the Flight MCU in the Flight MCU header board socket Plug the Benchtop 5V power supply into J1 the LED on the Flight MCU header board should start blinking indicating that it is running correctly Connect the Programming Debug Adapter to the JTAG port on the Flight MCU header board and to your PC Start your development software and verify that you can communicate with the Flight MCU Verify that the manual reset switch SW3 works properly Successful verification of the tables above an
3. This cutout enables the MHX transceiver to fit within the confines of the CubeSat s 10x10x10 cm size If you use the MHX transceiver you ll find that this cutout leaves enough room to attach your antenna cable to the MHX transceiver If you don t use the MHX transceiver you can put solar cells over the cutout run other wires in and out of the CubeSat there etc It doesn t look like I can fit all of my payload into a 10x10x10cm CubeSat Kit Are larger CubeSat Kits available Yes 10x10x20cm and 10x10x30cm CubeSat Kits are available They are identical to the 10x10x10cm CubeSat Kit except for their chassis which are correspondingly longer Environment What temperature range is the CubeSat Kit designed for All of the parts in the CubeSat kit that are destined for space operate over the 40 to 85 C industrial temperature range What kinds of glues and or epoxies are used in the CubeSat Kit All of the components in the CubeSat Kit are permanently riveted positively fastened with machine screws or soldered to the Flight Module Some space grade adhesives are used to lock certain fasteners in place What kind of wiring does the CubeSat Kit have The only wires in the CubeSat Kit connect the Remove Before Flight and Launch switches to the Flight Module or to user 34 UM 3 Pumpkin CubeSat Kit User Manual The RTOS that runs in tiny places User Man ual Sm aS lg jp aa circuitry All other inter board interconnects a
4. aaam __ aa conceivable that the two might be connected by a wire harness between one or more PC 104 modules and the PCB pads for the CubeSat System Bus connectors Note Due to clearance issues a PC 104 module cannot occupy Slot 1 if the MHX transceiver is fitted to the Flight Module 7 Flight Module 4 User Modules 1 Low Profile User Module This configuration eschews the transceiver on the Flight MCU in favor of a user supplied transceiver on one of the user modules Choosing not to use the MHX transceiver reduces the spacing between Slot 0 and Slot 1 to only 15mm and enables the fitting of an additional module in Slot 5 Note The user module in Slot 5 has additional constraints on its component height Stackthrough style connectors cannot be used on this module 63 im J ES SLOT 5 SLOT 4 SLOT 3 SLOT 2 SLOT 1 SLOT O L EHA o Figure 5 Flight Module 4 User Modules 1 Low Profile User Module UM 3 Pumpkin CubeSat Kit User Manual 13 The RTOS that runs in tiny places User Man ual 8 Non stacking Topology An alternative board interconnect scheme seen in some CubeSats designs is to keep the variou
5. Power 5V 5V_SW 5V_USB VCC User Manual The Flight MCU has multiple clock options which are normally user configured by stuffing the appropriate crystals X1 X4 and capacitors where required Each Flight MCU has a programming and debugging connector J2 for use with standard development tools There are two main power busses on the Development Board 5V and VCC VCC_IO 5V_USB and 5V_SW are also present GND ground i e OV is common across all of the circuitry 5V is connected directly to the PC 104 bus connectors H3 H4 and is also available on the CubeSat System Bus connectors H1 H2 Connector J1 is directly connected to 5V and therefore can be used to supply 5V to the CubeSat from an external power source regardless of the status of the Remove Before Flight and Launch switches 5V_SW is controlled by the Flight MCU and provides 5V power on demand to the transceiver 5V_SW is available on CubeSat System Bus connector H1 5V_USB is derived directly from the USB connector and is available on CubeSat System Bus connector H1 VCC is normally generated on the Development Board from 5V via an ultra low quiescent current low dropout LDO regulator UM 3 Pumpkin CubeSat Kit User Manual 19 The RTOS that runs in tiny places vcc_lo GND Power Switching Level Shifting Reset 20 User Manual U5 The LDO regulator s output is set to the desired VCC VCC s value is chosen
6. A compiler IDE for the Flight MCU To transform a CubeSat Kit into a working CubeSat satellite you ll need to e Decide on the internal configuration of your CubeSat e Solder a few connectors and wires e Design and implement a power system e g solar cells batteries regulators etc tailored to your CubeSat e Implement a communications system radio antenna for your CubeSat e Design and implement any other electronics your CubeSat requires e Integrate all of these items your payload into your CubeSat e Write software to interface to and control the CubeSat Note The CubeSat Kit is designed to accept the Microhard Systems http www microhardcorp com MHX 2400 Embedded Wireless Modem This module operates in the 2 4000 2 4835 GHz ISM band More information can be found at Microhard s website UM 3 Pumpkin CubeSat Kit User Manual S sawo User Manual The RTOS that runs in tiny places Getting Started Development Board Flight MCU Unpack the following CubeSat Kit items e Development Board e Flight MCU header board e Flight MCU programming debug adapter e USB module e Benchtop 5V power supply e USB cable Verify that the jumpers on the Development Board are set to their default values for your Flight MCU Jumper Setting A JP1 OFF JP2 ON JP3 ON JP4 OFF JP5 ON JP6 OFF JP7 ON JP8 ON JP9 ON JP10 ON JP11 OFF JP12 OFF JP13 OFF JP14 2 3
7. Kit include a radio transceiver No but you can buy one from Microhard Systems http www microhardcorp com off the shelf plug it into the Flight Module add an antenna and you re ready to begin sending and receiving UM 3 Pumpkin CubeSat Kit User Manual 31 The RTOS that run s in tiny places User Manual prefer to use design my own radio Will that work in the CubeSat Kit Yes The CubeSat Kit can be configured in various ways You can put your own radio in the CubeSat Kit Do I have to create my own Printed Circuit Boards PCBs in order to use this CubeSat Kit No For simple designs you can use the Flight Module s powerful MCU as your primary controller You can put your own electronics serial EEPROMs sensors power supply connectors etc on any PC 104 prototyping cards available from various manufacturers and connect them via the CubeSat System Bus connectors Sophisticated users with complex designs will want to build their own modules on custom PCBs Again these will connect to the Flight MCU via the CubeSat System Bus connectors User modules can also connect to the PC 104 bus or even the PC 104 Plus bus Why is the PCB mounting scheme of the CubeSat Kit designed around the PC 104 mechanical specifications 32 First the PC 104 specification has a simple pass through connector scheme that is well suited to the tight confines of the CubeSat The CubeSat System Bus connector is the same
8. based on the Flight MCU VCC is available on the CubeSat System Bus connector H2 The regulator s output can be disabled by taking OFF_VCC available on CubeSat System Bus connector H1 high i e to VCC The nominal VCC voltage is 3 3V This voltage is generated by the serial to USB converter and powers the interface between the Flight MCU and the serial to USB converter VCC_IO is either _3 3V or 5V depending on the Flight MCU Note The USB specification stipulates that a maximum of 500mA be drawn by an USB device A star grounding scheme is used at the Flight MCU s analog and digital ground pins to minimize noise 5V power to the transceiver is controlled by the Flight MCU via a P channel MOSFET Logic level voltage shifting is employed via N channel MOSFETs wherever signals generated on the VCC rail must control devices on the 5V rail An on board Reset Supervisor U4 is provided to externally reset RST NMI the Flight MCU should its power drop below a predetermined setpoint An external reset signal RESET is available on the CubeSat System Bus connector An alternate Reset Supervisor U9 can be fitted UM 3 Pumpkin CubeSat Kit User Manual The RTOS that runs in tiny places USB User Manual A serial to USB 1 0 interface utilizing FITDI s FT232BM is provided This interface is powered by the USB host to which it is connected e g a laptop PC and draws no power from the CubeSat The MCU sees th
9. configure the I O pins as digital inputs or outputs and enable one of the interfaces The I O pins that enable the interfaces must always be configured as digital inputs or outputs A few precautions must be taken for this to work properly You can either selectively isolate your analog sources from the Flight MCU bus e g by using an analog switch or you can buffer the analog sources in a manner that s tolerant of being driven by a digital signal appearing at the I O pin Can I use the Flight MCU s second UART to talk to serial devices other than the USB to Serial converter and MHX transceiver Yes When neither of these on board interfaces is enabled you can talk to other serial devices You must ensure that when either the USB to serial converter or the MHX transceiver is enabled your other serial devices are disabled tri state hi Z on the UART s receive data pin Can the Flight MCU talk to both the USB to serial converter and the MHX transceiver at the same time No Only one interface should be active at the same time Control of the interfaces is under the Flight MCU s control The USB to serial converter is envisioned as an on the ground communications link and the MHX transceiver is envisioned as an in flight communications link Therefore you would not normally need to have both active at any time UM 3 Pumpkin CubeSat Kit User Manual 39 The RTOS that runs in tiny places 40 User Manual Why don t the
10. data and control signal names for the two interfaces match They don t match because one is Data Terminal Equipment DTE and the other is Data Communications Equipment DCE What kind of handshaking do the interfaces support The USB to serial converter interface supports simple hardware handshaking RTS CTS as well as software handshaking XON XOFF The MHX transceiver supports full hardware handshaking RTS CTS DSR DTR DCD as well as software handshaking Can I reset the interfaces Yes Each interface can be reset by the Flight MCU Can an external processor interface with the USB to serial converter No To move data from an external processor e g a PC 104 SBC through the USB to serial converter will require that the external processor communicate with the Flight MCU serving as an intermediary Can an external processor interface with the MHX transceiver Yes directly over the CubeSat System Bus This requires that the external processor apply 5V power to 5V_SW All of the MHX transceiver s data and control signals except DCD are available on the CubeSat System Bus connectors Can I use the USB port in space If your USB cable is long enough The USB chip uses almost as much power as the Flight MCU Isn t that wasteful The USB interface is designed so that it is only powered when connected to an external host e g a laptop PC At all other times the USB interface consumes no power
11. leaves room for a low profile user module in Slot 1 but not enough for a PC 104 module in that slot The PC 104 connectors on the Flight Module are of the non stacking type They are either 15mm or 25mm tall depending on whether a transceiver is fitted to the Flight Module All other PC 104 connectors are of the conventional stackthrough type Note Only J1 pins 1 4 and 29 32 and J2 pins 0 3 and 16 19 are implemented on the Flight Module Therefore to connect J1 or J2 to a PC 104 module in Slot 1 2x4 headers instead of 2x32 and 2x20 respectively are used Warning The MSP430 on the Flight Module is a 3 3V only MCU Therefore level shifting circuitry must be used when interfacing this MCU to the PC 104 bus which runs at a nominal 8 And taller PC 104 bus connectors UM 3 Pumpkin CubeSat Kit User Manual The RTOS that runs in tiny places User Manual 5V Connecting 5V to any pin on the MSP430 will irreparably damage the device Texas Instruments and other manufacturers have logic families specifically designed to translate 3 3V to 5V sometimes bidirectionally Electrical Compatibility Interfacing to PC 104 The ISA bus specification around which PC 104 is built is designed fundamentally for microprocessors not microcontrollers MCUs I e it is designed for use with processors that have external data and address busses and the associated control signals The ISA bus is not well suited for use with m
12. much larger PCB to facilitate access to the various systems on board It also includes provisions for multiple power supply sources and jumpers to isolate parts on the system It also includes some additional circuitry not available on the Flight Module e g indicator LEDs and an RS 232 port Electrically the Flight Module is a subset of the Development Board Why aren t the PC 104 and CubeSat System Bus connectors soldered to the Development Board and Flight Module There are three basic configurations for the CubeSat kit each of which uses different connectors The kits are supplied with the connectors for the most common configuration as separate parts By doing this you won t have to unsolder the connectors and risk damaging the boards if you need one of the alternate configurations Assembly Mechanical What is the CubeSat Kit structure made of The CubeSat Kit is made from sheet aluminum in thicknesses appropriate for each individual part All external fasteners are made from stainless steel UM 3 Pumpkin CubeSat Kit User Manual 33 The RTOS that runs in tiny places User Man ual a RE I Is the CubeSat Kit an inch or metric design All of the user serviceable fasteners are metric All relevant dimensions are presented in metric units Is the CubeSat Kit structure hard anodized Yes to prevent galling when in contact with the CubeSat launcher Why is there an oval cutout on the front face of the CubeSat Kit
13. that the easiest way to interface the Flight MCU to a PC 104 or PC 104 Plus module with an x86 class processor running Linux is via a serial port This is advantageous because RS 232 drivers operate at RS 232 voltage levels which bypasses the issue of 3 3V to 5V translation So You could place your PC 104 module on the Development Board and connect its processor to the Flight MCU via this serial port You would need to eventually design your own RS 232 interface on a user module when you integrate your design into a CubeSat The RS 232 driver is not incorporated into the Flight Module because that would unnecessarily constrain the design Alternatively you could use the RS 232 port for print style debugging and simply ignore it when you integrate your design into a CubeSat UM 3 Pumpkin CubeSat Kit User Manual The RTOS that run s in tiny places User Manual Communications Interfaces USB and MHX Transceiver How can use the Flight MCU s A D inputs to sample voltages throughout my CubeSat They re connected to the USB and MHX transceiver interfaces You can use most of the Flight MCU s analog inputs for voltage sampling because the USB to serial converter and the MHX transceiver are normally isolated from the Flight MCU s bus When you want to sample disable the interfaces configure the I O pins as analog inputs and sample When you want to connect to either the USB to serial converter or the MHX transceiver
14. 4 P2 7 0 1 0 VCC Flight MCU Port P2 25 26 5V PWR PC 104 Bus 5V 27 28 VCC PWR Flight Module power 29 32 GND PWR System GND Launch Switch Normally ii LS NG VO Closed Terminal 35 36 LS_NO o Launch Switch Normally Open Terminal Remove Before Flight Switch Sue BENG vo Normally Closed Terminal Remove Before Flight Switch 32 40 BBR VO Common Terminal UM 3 Pumpkin CubeSat Kit User Manual Table 13 CubeSat System Bus Connector H2 25 Taa aalo User Manual PC 104 Bus As detailed in PC 104 Compatibility only 5V and GND are available to from the PC 104 bus Therefore only a 32 pin subset of the total of 104 PC 104 connector pins are implemented Additional Components and Circuitry Bypass Capacitors Bypass capacitors across each power supply are provided Test Points Test points for signals of interest are provided Additional Features of the Development Board Power The Development Board accepts 6 24V dc input as a source for system power via an additional LDO regulator with fixed 5V output 6 24V dc can be applied via a 2 1 or 2 5mm dc power plug center is polarity or via laboratory banana jacks GND is black is red Each major power connection can be interrupted by means of a jumper This allows the user to isolate any part of the power system from another which is especially useful when measuring currents Reset A manual Flight MCU Reset pushbutton switch is provided Indicators LED indicato
15. Flight Module does not include power required by the transceiver 36 UM 3 Pumpkin CubeSat Kit User Manual The RTOS that runs in tiny places User Man ual I allows the Flight MCU to keep the MHX transceiver power on while the interface is disabled and the I O pins are used for other purposes 2 For CubeSat Kit configurations that employ the Flight MCU as the main processor 5V_SW can be used as a power supply signal that is under the Flight MCU s control Can leave the Flight MCU on all the time while in orbit Theoretically yes Its power consumption is so small especially in its power saving modes that you can probably leave it on all the time How do manage power consumption in the CubeSat Kit The biggest drain on your power supplies is likely to be your transceiver radio especially when transmitting The Flight MCU can control power to the MHX transceiver so that it only consumes power when the Flight MCU is ready to transmit data Does the CubeSat Kit include a power supply A 5V external table top power supply is included for use with the Development Board and the Flight Module It is used to power the Development Board and can also power an assembled CubeSat through the external power connector It is up to you to design your own internal power system for your CubeSat This will normally involve solar cells and or batteries and may require outputs at multiple voltages e g 3 3V and 5V CubeSat power s
16. System Bus connectors can be soldered to it to mate with a Flight Module Can use off the shelf PC 104 modules in the CubeSat Kit Yes Any PC 104 module can be used If it s a 5V only module it will plug right into the module stack If it requires other voltages you ll have to provide them too Can I use PC 104 Plus modules in the CubeSat Kit Yes Any PC 104 Plus module can be used The Flight Module only has 5V and GND for 8 or 16 bit PC 104 cards If your PC 104 Plus module requires other voltages you ll have to provide them too 11 Physical packaging issues dictate that a user module can connect to the PC 104 bus and to either the PC 104 Plus bus or the CubeSat System Bus but not both UM 3 Pumpkin CubeSat Kit User Manual The RTOS that runs in tiny places User Manual plan to use a PC 104 SBC running Linux in my CubeSat and I m not sure want need the Flight Module Can I remove it to save weight The Flight module performs several functions in addition to being the home of the Flight MCU The Remove Before Flight switch and MHX transceiver are mounted to it Additionally there is not enough room to mount a PC 104 sized module in Slot 0 Therefore you should probably keep the Flight Module and consider assigning it another role perhaps that of a system supervisor or backup processor outside of the functionality you plan to implement on your Linux SBC Why can t I use the MHX transceiver wi
17. T N 1 4 2 user module o 2 15mm 2 ST N 2 ST N 3 PC 104 module 3 15mm 3 3 ST N 4 PC 104 module 4 23mm 4 4 ST N 5 n a 5 n a 5 5 0 Flight MCU 0 25mm 0 0 NST T 1 PC 104 module 1 15mm 1 1 ST N 5 2 PC 104 module Ae 2 15mm 2 2 ST N 3 PC 104 module 3 15mm 3 3 ST N 4 PC 104 module 4 13mm 4 4 ST N 5 n a 5 n a 5 5 0 Flight MCU 0 15mm 0 0 NST N 1 PC 104 module 1 15mm 1 1 ST N 6 2 PC 104 module ae 2 15mm 2 2 ST N 3 PC 104 module 3 15mm 3 3 ST N 4 PC 104 module 4 15mm 4 4 ST N 5 user module LP 5 6mm 5 5 END 0 Flight MCU 0 15mm 0 NST N 0 1 user module 1 15mm 1 ST N 1 7 2 user module yes 2 15mm 2 ST N 2 3 user module 3 15mm 3 ST N 3 4 user module 4 15mm 4 ST N 4 5 user module LP 5 6mm 5 END 5 8 0 Flight MCU s 0 0 user 0 1 5 n a y 1 5 n a 1 5 n a 1 5 n a END non stackthrough minimal protruding height above module s PCB surface surface mount recommended NST N non stackthrough normal height for 15mm stacking NST T non stackthrough tall height for 25mm stacking ST N stackthrough normal height for 15mm stacking Table 6 Summary of Example CubeSat Kit Configurations The topology of the configuration you choose for your CubeSat Kit affects which connectors should be installed on the Development UM 3 Pumpkin CubeSat Kit User Manual 15 The RTOS that runs in tiny p
18. UM 3 User Manual 750 Naples Street San Francisco CA 94112 415 584 6360 htto www pumpkininc com Pumpkin CubeSat Kit User Manual Pumpkin CubeSat Kit REV D2 September 17 2003 2000 2003 Pumpkin Inc and design MASSIF All rights reserved Specifications subject to change without notice Tlustration depicts CubeSat Kit with MHX 2400 modem Modem not included in CubeSat Kit Copyright 2003 Pumpkin Inc last updated on Sep 17 2003 All trademarks mentioned herein are properties of their respective companies The RTOS that runs in tiny places Introduction Background User Manual Pumpkin Inc s CubeSat Kit is an off the shelf OTS kit designed to radically reduce the time and effort required to build a functional satellite conforming to the current CubeSat http cubesat calpoly edu specification The CubeSat kit fully adheres to the CubeSat specification s electrical and mechanical requirements The included Pumpkin CubeSat Flight Module sports an ultra low power single chip microcontroller lt 100mW and a complete 80 pin system bus for expansion The Flight MCU is pre programmed with Pumpkin s Salvo Real Time Operating System RTOS to facilitate rapid software development A third party spread spectrum 2 4GHz transceiver module can be installed on the Flight Module without any modifications to the CubeSat Kit In addition to the Flight Module the 10x10x10cm CubeSat Kit can accomm
19. UM 3 Pumpkin CubeSat Kit User Manual The RTOS that runs in tiny places User Man ual a C P SI f aaa a iO Why aren t any MHX transceiver status indicators available to the Flight MCU or on the CubeSat System Bus connector All of the MHX transceiver s status information can be gleaned by reading from its internal registers Therefore these signals are unnecessary They are attached to LEDs on the Development Board as a visual aid prefer to use my own radio How can integrate it into the CubeSat Kit The simplest approach is probably to package your radio in the same form as the MHX transceiver so that it can be plugged into the MHX transceiver sockets You can then choose to control the radio from the Flight MCU or externally via the CubeSat System Bus Note that the MHX transceiver socket is supplied with 5V power from 5V_SW Can I use the USB to serial converter s serial memory chip for purposes other than USB configuration No it is not intended for general purpose use Shouldn t be concerned with the MHX transceiver s cable sticking out of the side of the CubeSat Kit Not really The MHX transceiver is quite large compared to the CubeSat and we felt that this was the best installation location for it The cable is still within the CubeSat specifications regarding items protruding above the CubeSat sides We recommend you use some mechanical means to ensure that the cable will stay connected to the transceiver Th
20. ans of connecting the Flight MCU s 48 I O pins and additional Flight MCU pins to user circuitry elsewhere in the CubeSat The CubeSat System Bus connector pinout is outlined below Signal Logic ae Pin s Name Type Level Description 1 8 P5 7 0 1 0 VCC Flight MCU Port P5 9 16 P4 7 0 VO VCC Flight MCU Port P4 17 24 P3 7 0 O VCC Flight MCU Port P3 25 XT2IN clock vce a a external crystal 26 VREF o vce Flight MCU internal A D reference 27 XT2OUT clock vcc jin ag external crystal 28 VEREF vce Flight MCU external reference External RESET to Reset 29 RESET l VCC Supervisor 30 VREF vce Flight MCU external reference 31 OFF_VCC VCC External disable of on board VCC regulator From USB Interface Must not 32 ONURE Re exceed 500mA Normally from 5V under ee ical Bide Flight MCU control 34 RST_MHX 5V_SW Transceiver Reset 35 CTS_MHX O 5V_SW Transceiver Clear to Send 36 RTS_MHX 5V_SW Transceiver Request to Send 37 DSR_MHX O 5V_SW Transceiver Data Set Ready 38 DTR_MHX 5V_SW Transceiver Data Terminal Ready 39 TXD_MHX 5V_SW Transceiver Transmit Data 40 RXD_MHX O 5V_SW Transceiver Receive Data Table 12 CubeSat System Bus Connector H1 Signal Logic ai Pin s Name Type Level Description 1 8 P6 7 0 VO VCC Flight MCU Port P6 9 16 P1 7 0 VO VCC Flight MCU Port P1 17 2
21. as the standard PC 104 stackthrough 40 pin connector a well established industry standard Second many potential CubeSat developers want to run sophisticated applications on their CubeSats that they can first develop on PCs By accommodating 5V only PC 104 modules the CubeSat Kit supports x86 class single board computers SBCs in the PC 104 form factor like the Diamond Systems http www diamondsystems com Prometheus SBC which was used in the successful QuakeSat project http www quakefinder com quakesat htm Naturally other PC 104 modules can also be used in the CubeSat Kit Third the mechanical layout of PC 104 modules leaves a considerable percentage of the total PCB area available for circuitry UM 3 Pumpkin CubeSat Kit User Manual The RTOS that runs in tiny places User Manual What equipment do I need to program the Flight MCU All you need beyond the CubeSat kit is a PC and a compiler Integrated Development Environment IDE The CubeSat Kit contains all of the hardware required to connect a PC to the Development Board and Flight MCUs for downloading programming and debugging Each CubeSat Kit also includes the Salvo RTOS for the MCU on the Development Board and Flight Module You will need a compiler to develop software for this MCU Low cost compilers and IDEs are commercially available What s the difference between the Development Board and the Flight Module The Development Board is on a
22. d the Flight MCU header board s LED blinking indicate that the Development board is properly configured for the Flight MCU Follow FTDI s http www ftdi com instructions and install the FTDI USB drivers on your PC Remove 5V power from the Development Board Install the USB module in H7 observing the correct orientation Reapply 5V power and verify the following Signal Location Value Vv 5V_USB TP11 oV VCC_IO TP13 oV Table 3 Voltages for Unpowered USB Module on Development Board for MSP430 Flight MCU Remove 5V power from the Development Board Connect the USB cable between the USB module and your PC Your PC should UM 3 Pumpkin CubeSat Kit User Manual The RTOS that runs in tiny places MHX Transceiver Additional Features UM 3 Pumpkin CubeSat Kit User Manual User Manual now recognize the USB device follow the FTDI instructions on completing the driver installation Verify the following Signal Location Value Vv 5V_USB TP11 5V VCC_lO TP13 3 3V RST_USB H7 3 3 3V Table 4 Voltages for Bus powered USB Module on Development Board for MSP430 Flight MCU Open a terminal application e g Windows Hyperterminal connect to the USB ports emulated Com port usually COM3 or COM4 and send a text file any text file to the Development Board You should see the Rx LED light up to indicate the reception of serial data Note You can send t
23. e fact that it is exposed to space is not cause for worry PC 104 How PC 104 compatible is the CubeSat Kit PC 104 boards that do not extend beyond the primary board dimensions of 90x96mm can be mounted inside the CubeSat Power 5V and ground connections to the Flight Module are provided in the J1 and J2 connectors UM 3 Pumpkin CubeSat Kit User Manual 41 The RTOS that runs in tiny places 42 User Manual Why are only a few of the PC104 bus pins implemented on the Flight Module Because the PC 104 bus is designed for microprocessors and not microcontrollers like the Flight MCU it is not easily interfaced to a microcontroller Therefore only 5V power and GND are connected from the Flight Module to the PC 104 bus When are PC 104 connectors required on the Flight Module The 2x4 PC 104 connectors are only required on the Flight Module when there is a PC 104 module in Slot 1 or when there are PC 104 modules in Slot 2 through Slot 4 and you haven t connected the 5V and GND signals on the CubeSat System Bus connectors to the PC 104 connectors in a user bridge module How many PC 104 cards can fit in the CubeSat Kit You can fit a total of 4 PC 104 cards in the 10x10x10cm CubeSat Kit They mount directly above the Flight Module Can use a PC 104 prototyping card to build a user module Yes The Diamond Systems http www diamondsystems com Proto 104 prototyping card can be used PC 104 and or CubeSat
24. e serial to USB converter as Data Terminal Equipment DTE The serial to USB converter H7 is isolated from the Flight MCU bus via the buffer Ul When the serial to USB converter is unpowered U1 is in a high impedance state When the serial to USB converter is powered VCC_IO powers U1 Normally the Flight MCU s P1 7 pulled high to VCC_IO is configured as an input To connect the Flight MCU to the serial to USB converter the Flight MCU must drive P1 7 LOW while U1 is powered Resistors R1 R4 are provided to avoid overcurrent damage if Flight MCU pins P3 7 and P6 0 2 are inadvertently configured as outputs when the interface is enabled Resistors R5 R8are provided to avoid overcurrent damage if the FT232BM s TXD RTS and RI pins are inadvertently configured as outputs when bit bang mode is selected The Flight MCU s interface to the USB subsystem is outlined in Table 8 Flight Associated MCU USB Signal Description Polarity Pin Name Enables the USB interface when P1 7 OE_USB LOW OV AND the USB Active LOW interface is active USB Transmit Data i e serial Active Ra TXD_USB data from USB to Flight MCU HIGH USB Receive Data i e serial Active P3 6 RXD_USB data from the Flight MCU to HIGH the USB P6 0 RTS_USB USB s Request to Send output Active LOW P6 1 DTR_USB the Transmit Ready Active LOW P6 2 PWE_USB USB s POWEREN output Active LOW P6 3 CTS_USB USB s Clear to Send input Acti
25. etween Slot 0 and Slot 1 Inter Slot Spacing Table 5 Slot Descriptions Mechanical Compatibility Since PC 104 connectors are used the normal distance between adjacent modules is 15mm 0 6 just like PC 104 However there are a few special cases Slot 0 Slot 4 and Slot 5 Slot 0 Spacing When an MHxX transceiver is fitted to the Flight Module 25mm instead of 15mm standoffs must be used between Slot 0 and Slot 1 Slot4 Spacing When Slot 4 is occupied by the last module its standoff will be approximately either 13 or 23mm in length dependent on the Slot 0 standoff length If a module is fitted in Slot 5 Slot 4 will use the standard 15mm standoff UM 3 Pumpkin CubeSat Kit User Manual The RTOS that runs Slot5 Spacing User Manual When Slot 5 is the last slot occupied by a module its standoff will be approximately 6mm in length Final Standoff Heights The approximate nature of the standoffs used for Slots 4 and 5 is due to tolerance build up and imperial metric size differences Users should measure the exact required height using a caliper on their assembled CubeSat kit and fabricate the necessary spacer by shortening an existing longer one Configuration Examples 10 With the CubeSat Kit users can configure their CubeSats in a variety of ways Examples 1 7 below employ a conventional board stacking topology which places user modules and or PC 104 modules above the Flight module in Slots
26. ext through the USB port with the Development Board off because the USB to serial interface is bus powered i e powered from the USB bus Reapply 5V power to the Development Board Remove 5V power from the Development Board Install the MHxX transceiver observing the correct orientation Attach an antenna to the transceiver Reapply 5V power and restart the terminal program on your PC From the terminal program issue the command T lt CR gt to enable the MHX Transceiver and transmit a burst of data for 5 seconds The TXMODE LED should light The transmission ends automatically and the TXMODE LED should extinguish The Development Board includes additional circuitry that is particularly useful when deriving power from other sources and for measuring current draw Refer to Circuit Description for more details The RTOS that runs in tiny places User Manual Configuring the CubeSat Kit User Modules CubeSat Kit Slots User provided Printed Circuit Board PCB modules must follow the PC 104 PCB layout in order to fit inside the CubeSat Kit and interface to the PC 104 bus if desired Additionally these modules must locate the CubeSat System Bus connectors properly so as to be able to interface to the Flight Module The CubeSat Kit is designed to accept user or PC 104 modules in addition to the Flight Module The locations of the modules are referred to as Slot 0 through Slot 5 where Slot 0 is at the Launch Switch end
27. hat can be implemented assuming a unipolar power supply i e voltage source where the terminal is OV and the terminal is greater than OV e g 5V Description Implementation Ground Lift with RBF CubeSat System Bus Connector H2 Connect Switch only CubeSat power supply to LS_NC and to power distribution circuitry Flight Module Development Board Connect ZP1 to ZP2 e CubeSat System Bus Connector H2 Connect CubeSat power supply to LS_NC and to power distribution circuitry e CubeSat System Bus Connector H2 Connect Power Interruption n with RBF Switch only w power supply to RBF_C and to Power Interruption e CubeSat System Bus Connector H2 Connect with RBF and Launch CubeSat power supply to RBF_C and to Switches LS_NC Table 11 CubeSat Global Power Disconnect Schemes Ground Lift with RBF and Launch Switches Table 11 illustrates how global power disconnect can be implemented without any discrete wires beyond those that connect the RBF and Launch switches directly to the Flight MCU Tip In a ground lift configuration the RBF and Launch switch NO terminals can be used to hold a power supply pin e g the terminal of discharged batteries at GND potential UM 3 Pumpkin CubeSat Kit User Manual The RTOS that runs in tiny places User Manual CubeSat System Bus The CubeSat System Bus on connectors H1 and H2 provide a me
28. icrocontrollers Interfacing a single chip microcontroller to the ISA bus usually involves a considerable amount of glue logic Additionally the speeds of processors on the ISA bus often greatly exceed those of popular microcontrollers further complicating the interface For the reasons above the CubeSat Kit s Flight Module makes no attempt to interface to the PC 104 bus save for 5V and GND We recommend that interfacing the Flight MCU to the PC 104 bus be done on the user module in Slot 1 Since all of the Flight Module s Y O pins are available on the CubeSat Bus Connectors any interface between the PC 104 bus and the Flight MCU can be implemented For example if you wanted to implement an 8 bit data port with handshaking between the PC 104 bus and the Flight MCU you would probably use one of the Flight MCU s 8 bit I O ports along with a few dedicated handshaking lines This circuitry would reside on the Slot 1 User Module which connects to the Flight Module in Slot O via the CubeSat Bus connector and to the PC 104 bus of Slots 2 4 via the PC 104 bus connectors PC 104 Plus Compatibility The CubeSat Kit does not directly support the PC 104 Plus 32 bit standard However PC 104 Plus modules can be mounted in any 9 E g a SOMHz 486 class processor UM 3 Pumpkin CubeSat Kit User Manual 29 The RTOS that runs in tiny places User Man ual eee eee slot that normally accepts PC 104 modules as long as there is no mechanica
29. imultaneous external control of the transceiver and Flight MCU enabling of the transceiver interface must be avoided It is recommended that the interface and 5V_SW circuitry be removed if you intend to control the transceiver externally via the CubeSat System Bus connector H2 Remove Before Flight and Launch Switches Two separate high reliability switches are provided for the CubeSat s Remove Before Flight RBF and Launch switch specifications Additionally a dedicated pair of terminals ZP1 amp ZP2 are provided for a GND connection The RBF Switch C and NO terminals are connected when the CubeSat s RBF pin is in place When the RBF pin is removed the RBF switch C and NC terminals are connected UM 3 Pumpkin CubeSat Kit User Manual 23 The RTOS that runs in tiny places User Manual 24 Direct Wiring The Launch Switch C and NO terminals are connected when the CubeSat is placed into the CubeSat launcher When the CubeSat is released from the launcher the Launch switch C and NC terminals are connected All of the switch contacts C common NC normally closed and NO normally open are available should the user decided to wire directly to the switches Wiring via the CubeSat System Bus 4 of the 6 switch terminals are provided on the CubeSat System Bus connector H2 and implement 4 of the 5 distinct terminals of two serially connected switches The following CubeSat global power disconnect schemes are examples of w
30. iz http www digi key com UM 3 Pumpkin CubeSat Kit User Manual
31. l interference between the PC 104 Plus module s 32 bit connectors and the rest of the system 30 UM 3 Pumpkin CubeSat Kit User Manual The RTOS that runs in tiny places User Manual Frequently Asked Questions FAQ General What is the CubeSat Kit designed to do The CubeSat Kit is designed for low mass high strength maximum useable surface area minimum power consumption and maximum configurability while conforming to the CubeSat specifications What do I have to add to the CubeSat Kit to turn it into a functional satellite that s ready for launch At a minimum you ll need to add a power source i e batteries solar cells etc and your payload experiment You ll want to add a transceiver and an antenna if you plan to communicate with your CubeSat Plus you ll need to program the Flight MCU to run your CubeSat and handle communications etc Why doesn t the CubeSat kit include an antenna solar cells The design of items like antennas and power supplies is very mission oriented and should be tailored to each individual CubeSat The CubeSat Kit is a general purpose kit and is designed to satisfy the basic requirements of the CubeSat specifications With the CubeSat Kit you don t have to worry about building a sturdy yet light enclosure adding Remove Before Flight and Launch Switches creating a working connector scheme picking a microcontroller etc We ve done all of that for you Does the CubeSat
32. laces User Man ual ee eee eS Board and Flight Module Each CubeSat kit is supplied with a complete set of connectors for topologies that locate Slot 1 25mm above Slot 0 If your configuration requires Slot 1 to be only 15mm above Slot 0 or if you will be using a non stacking topology then you will need to source your own connectors instead of using the supplied ones It is up to the user to solder the connectors onto the Development Board and Flight Module and to any user modules PC 104 modules are already supplied with the correct stackthrough connectors 16 UM 3 Pumpkin CubeSat Kit User Manual The RTOS that runs in tiny places Circuit Description Overview Flight MCU User Manual Please refer to Schematic Diagrams while reviewing this section Note The Development Board and Flight Module share the same circuitry The Development Board has additional development and debugging features that are omitted from the Flight Module The descriptions and reference designators below are for the Development Board All of the I O pins as well as some additional pins of the Flight MCU microcontroller are connected to the CubeSat System Bus Power provided from elsewhere in the CubeSat is regulated if required to meet the MCU s voltage requirements Power switching and level shifting are implemented as necessary A reset supervisor is employed on the MCU s power bus A bus powered USB interface is provided with isolati
33. numbered 0 through 5 The CubeSat System Bus and the PC 104 bus are where applicable connected from one module to another via PC 104 style stackthrough connectors The CubeSat System Bus connectors are on the opposite side of the CubeSat from the PC 104 connectors The CubeSat System Bus connectors 2x20 pins each are identical to the PC 104 standard s J2 16 bit extension connector Note The examples below are for a 1U CubeSat 10x10x10 cm Naturally the numbers of user modules and PC 104 modules can be increased in 2U 10x10x20 cm and 3U 10x10x30 cm CubeSats 1 Flight Module MHX Transceiver 1 User Module This configuration uses the Flight Module with an MHX transceiver mounted to it and a user module that interfaces the user s payload with the Flight MCU on the Flight Module The CubeSat s operating software resides in the Flight MCU The Flight module is connected to the user module via the two CubeSat System Bus connectors For this configuration 25mm standoffs are used between the Flight MCU Slot 0 and the user module Slot 1 to make room for the MHX transceiver UM 3 Pumpkin CubeSat Kit User Manual The RTOS that runs in tiny places User Manual 2 Flight Module MHX Transceiver 4 User Modules In this configuration the CubeSat System Bus is extended through multiple user modules To make room for the MHX transceiver 25mm standoffs are used between the Flight Module in Slot 0 and the user mod
34. odate up to 4 four 8 or 16 bit PC 104 compliant modules up to 5 five user modules or a combination of both The goal of the CubeSat project http cubesat calpoly edu is to deliver 1kg payloads in a 10cm cubed package into low earth orbit at low cost Groups around the world are developing their own CubeSats The CubeSat Kit evolved from a hardware and software co design process By combining a low power single chip microcontroller with a weight conscious mechanical design the CubeSat Kit s available payload can be maximized Design Partnership Pumpkin is partnering with design MASSIF to bring you the CubeSat Kit 2 User modules in Slot 5 have additional height restrictions UM 3 Pumpkin CubeSat Kit User Manual The RTOS that runs in tiny places Motivation The CubeSat Kit UM 3 Pumpkin CubeSat Kit User Manual User Manual z Cc PUMPKIN W Figure 1 CubeSat Kit Partners Osi Pumpkin has over 15 years experience in analog and digital hardware design and development embedded programming and product design Pumpkin will supply software electronic hardware documentation and web space for the project design MASSIF has over 15 years of experience taking products from concept to market design MASSIF s primary responsibility will be the mechanical design and packaging of the CubeSat kit Both companies are actively involved in multiple projects in Silicon Valley Both Pumpkin and design MASSIF are
35. of the CubeSat Modules are mounted in a stack of PCBs and connectors via threaded aluminum standoffs PC 104 style The stack begins with the Flight Module in Slot 0 just inside the CubeSat Kit s top cover and ends with the final slot s standoffs being attached to the CubeSat Kit body inside the bottom cover The smallish dimensions of the CubeSat introduce certain limits on the modules when fitted in certain Slots The constraints that deviate from the PC 104 specification are listed in Table 5 and are all mechanical in nature UM 3 Pumpkin CubeSat Kit User Manual The RTOS that runs in tiny places User Manual Slot Accepts Height Constraints on Module 15mm a e Module can be mounted 0 Flight Module S Cannot accept MHX transceiver if Slot 1 is occupied by a PC 104 module User module must provide powered PC 104 connectors or include PC 104 stack through connectors if PC 104 modules are used in Slots 2 5 User module or Can be occupied by a PC 104 module if 1 PC 104 15mm connectivity between user modules module and the Flight Module is not required When MHX transceiver is fitted on Flight Module component keep out area on underside of module must be observed User module or 2 PC 104 15mm module User module or 3 PC 104 15mm module User module or oun 4 PC 104 or module 23mm Greatly reduced topside component 5 User module 6mm height Only available when 15mm low profile spacers are used b
36. on between it and the MCU Provisions for a transceiver are also provided again with isolation between it and the MCU Voltage level shifting and power switching are provided where necessary Remove Before Flight and Launch switches are also provided The Flight MCU H6 a single chip ultra low power microcontroller with 48 I O pins is connected to the CubeSat System Bus connectors H1 H2 A few of the MCU s I O pins are dedicated or semi dedicated to interfacing with and or controlling other subsystems 6 I e the USB system is powered by the 5V that is provided by the USB cable UM 3 Pumpkin CubeSat Kit User Manual 17 Reig that runs in tiny places User Man ual Flight MCU Availability on MSP430 based Designs Pin s P1i 0 6 Free to user Dedicated to control of USB interface i e normally a digital P1 7 output May be used as a digital inout to sense whether VCC_IO is present P2 0 7 Free to user P3 0 3 Free to user P3 4 Free to user on Flight Module On Development Board can be i connected to on board RS 232 receiver Free to user on Flight Module On Development Board can be connected to on board RS 232 transmitter Semi dedicated as MCU transmit data to USB and transceiver P3 6 interfaces Can be used in any other way when neither USB nor transceiver interface is active Semi dedicated as MCU receive data from USB and transceiver P3 7 interfaces Can be used in any other way when neithe
37. r USB nor transceiver interface is active P4 0 5 Free to user P4 6 Dedicated to controlling 5V_SW power P4 7 Free to user P5 0 7 Free to user Semi dedicated to USB and transceiver control interfaces When either the USB or transceiver interface is active these pins map to the following digital I O functions DTE DCE where applicable P6 0 RTS CTS P6 1 DTR DSR P3 5 Pelee P6 2 PWE DCD P6 3 CTS RTS P6 4 RI DTR P6 5 RST RST When neither the USB nor the transceiver interface is active then these pins are free for any purpose P6 6 Dedicated to control of transceiver interface P6 7 Free to user Table 7 Flight MCU I O Pin Usage From Table 7 we see that of the Flight MCU s 48 I O pins only 3 are permanently dedicated to on board subsystems The Flight MCU s UARTs can also interface with other off board serial devices as long as those devices can be selected independently of the on board USB and transceiver Note On the Development Board the Flight MCU is mounted on a separate PCB and connects to the Development Board via four headers This allows the use of different Flight MCUs on the Development Board Each Flight Module has its MCU soldered directly on it There are dedicated Flight Modules for each type of supported Flight MCU 18 UM 3 Pumpkin CubeSat Kit User Manual The RTOS that runs in tiny places Clock Sources JTAG etc
38. radigms for embedded programming The Internet is full of information on this subject Because Pumpkin s http www pumpkininc com Salvo RTOS is an event driven RTOS you will be able to minimize power consumption while maximizing functionality in the Flight MCU How do interface to the USB port You ll need FTDI s http www ftdi com drivers to interface your PC to the CubeSat Kit s USB port You can use the USB port as a simple terminal interface to the Flight MCU or you can write your own software in the Flight MCU and or the host side to do things like serial bootloaders etc UM 3 Pumpkin CubeSat Kit User Manual S salvo User Manual The RTOS that runs in tiny places Discussion Forums A series of CubeSat User Forums have been created on the Pumpkin web site for the express purpose of discussing issues that surround the CubeSat kit Announcements notices links to relevant files etc will all be posted to the Forums To access the forums choose the Forums link from Pumpkin s home page New users must register before they are allowed to post new topics or reply to existing ones Note We would like all discussions regarding the CubeSat kit to take place in the Forums not via private email UM 3 Pumpkin CubeSat kit User Manual 45 User Manual The RTOS that runs in tiny places Printed Circuit Board Layouts Development Board
39. re done with 0 100 spacing headers Payload My CubeSat payload is very flat Can I put it on a PC 104 card Sure If you design your payload to fit inside a PC 104 module s form factor you can stack it along with the other user modules and PC 104 modules in your CubeSat My CubeSat payload measures 5x5x5cm Can the CubeSat Kit accommodate it Yes With only the Flight MCU in place there s plenty of room for large payloads You may want to consider mounting any user modules against the side walls of the CubeSat Kit How can I run wires from a module to the top surface of the CubeSat Kit the one where the Flight Module is mounted There is a 4 7mm slot between the front edge of the Flight Module and the CubeSat inner wall To reach that surface from inside the CubeSat e g to wire solar cells route your wires through that slot The allowable height on Slot 5 is only 6mm What is Slot 5 good for Slot 5 is immediately below the CubeSat Kit s bottom cover Therefore it s an ideal location to place sensors that must be exposed to space e g a miniature camera lens Just cut a hole in the bottom cover that s large enough for the camera lens to pass through and not violate the CubeSat s allowable external dimensions UM 3 Pumpkin CubeSat Kit User Manual 35 oe aalo User Manual Electronics How much power does the Flight MCU take The Flight MCU uses an ultra low power microcontroller At full speed the entire Fligh
40. rs are provided for 5V VCC USB Rx Tx status and transceiver status 26 UM 3 Pumpkin CubeSat Kit User Manual S savo User Manual The RTOS that runs in tiny places USB The Development Board uses a replaceable USB module RS 232 A micro power RS 232 transceiver configured as DTE for software XON XOFF handshaking is provided It can be selectively enabled or disabled Prototyping Area The Development Board includes a 26x30 0 100 grid for use as a prototyping area Additionally two 1x30 0 100 columns of GND and two 1x15 1x15 0 100 columns of 5V VCC power are provided UM 3 Pumpkin CubeSat Kit User Manual 27 The RTOS that runs in tiny places User Manual PC 104 Compatibility The PC 104 standard provides electrical and mechanical specifications for embedded systems using the PC and PC AT ISA bus standard in a custom form factor PC 104 cards are popular in industrial control and monitoring and provide an OTS means of obtaining considerable computing and I O power in a compact form factor Mechanical Compatibility Connectors Voltages 28 The CubeSat Kit is designed to accept stackthrough PC 104 cards above the Flight Module The restrictions on the card slots are listed in Table 5 25mm 1 M3 threaded spacers are normally used between adjacent slots If a transceiver is not fitted on the Flight Module Slot 0 15mm spacers should be used between Slot 0 and Slot 1 This configuration
41. s PCBs on the inside surfaces of the CubeSat freeing the central volume for payload This can also be achieved with the CubeSat kit It requires that a user module interface to the Flight Module by plugging into the Flight Module at a right angle using alternate connectors Overview of Examples Table 6 summarizes the configuration examples listed above This may require a custom small intermediate PCB between the Flight Module and the user module in order to locate the user module against the CubeSat s inner skin 14 UM 3 Pumpkin CubeSat Kit User Manual The RTOS that runs in tiny places User Manual MHX Connectors Slots Xevr Standoffs CubeSat PC 104 OK System Bus Bus 0 Flight MCU 0 25mm 0 NST T 0 1 user module 1 1 ST N 1 1 2 payload yes 2 2 2 3 payload 3 3 3 4 payload 4 4 4 5 n a 5 n a 5 5 0 Flight MCU 0 25mm 0 NST T 0 1 user module 1 15mm 1 ST N 1 2 2 user module yes 2 15mm 2 ST N 2 3 user module 3 15mm 3 ST N 3 4 user module 4 13mm 4 ST N 4 5 n a 5 n a 5 5 0 Flight MCU 0 25mm 0 NST T 0 1 user module 1 15mm 1 ST N 1 NST N 3 2 PC 104 module a 2 15mm 2 2 ST N 3 PC 104 module y 3 15mm 3 3 ST N 4 PC 104 module 4 13mm 4 4 ST N 5 n a 5 n a 5 5 0 Flight MCU 0 15mm 0 NST T 0 1 user module 1 15mm 1 S
42. s up the transceiver as well as U3 Resistors R9 R12 are provided to avoid overcurrent damage if Flight MCU pins P3 7 and P6 0 2 are inadvertently configured as outputs when the interface is enabled The Flight MCU s interface to the transceiver subsystem is outlined in Table 10 UM 3 Pumpkin CubeSat Kit User Manual The RTOS that runs in tiny places External Control User Manual Flight Associated MCU Transceiver Description Polarity Pin Signal Name Enables the transceiver interface f P6 6 OE_MHX when LOW 0V Active LOW Transceiver Receive Data i e Active P3 7 RXD_MHX serial data from transceiver to HIGH Flight MCU Transceiver Transmit Data i e Active P3 6 TXD_MHX serial data from the Flight HIGH MCU to the Transceiver P6 0 CTS_MHX Transceiver Clear to Send Active LOW output P6 1 DSR_MHX eee Bala Set Rody Active LOW P6 2 DCD_MHX koa Data Carrier Detect Active LOW P6 3 RTS_MHX H Request to Send Active LOW P6 4 DTR_MHX Transceiver Data Terminal Active LOW Ready input P6 5 RST_MHX Transceiver Reset input Active LOW Table 10 Flight MCU to Transceiver Interface Signals The transceiver can be controlled externally i e by a processor other than the Flight MCU This is done by applying 5V to the 5V_SW terminal on the CubeSat System Bus connector H1 Most of the transceiver s control signals are available on the CubeSat System Bus connector H1 Warning S
43. t Module should consume no more than 20mA 3 3V 66mW By taking advantage of the MSP430 s power saving design and the event driven Salvo RTOS the average current should drop to well below ImA 3 3mW Why is a linear regulator used to generate VCC I thought switchers are more efficient A low dropout LDO linear regulator was chosen for this application primarily because it requires fewer parts thus enhancing reliability and reducing weight than most switchers and the Flight MCU s power consumption is so low that the overall system power savings would be negligible with a switcher If your CubeSat already generates a suitable VCC you should remove the regulator on the Flight Module and feed it VCC via the CubeSat System Bus connector What kinds of electronic components are used in the CubeSat Kit Primarily small surface mount components like 0805 and 1206 passive packages and TQFP chip packages With some skill and experience they can be reliably soldered by hand How much current can the Remove Before Flight and Launch Switches conduct They are each rated for 10A The same switches are used in the 10x10x10cm 10x10x20cm and 10x10x30cm CubeSat Kits Why are separate signals from the Flight MCU used to enable 5V_SW power and the MHX transceiver interface This is done primarily for two reasons 1 The MHX transceiver takes a relatively long time to power up The ON_ 5V signal 10 MHz for an MSP430 based
44. th a PC 104 module in Slot 1 Software There isn t enough room The PC 104 Plus specification calls for approximately 5mm of clearance below any PC 104 Plus card PC 104 Cards often have components on the underside of the PCB too With the MHX transceiver on the Flight Module there simply isn t enough room to accommodate components on the underside of the module in Slot 1 To use the MHX transceiver with PC 104 cards you could design your own user module for Slot 1 and place your PC 104 module in Slot 2 or higher Or you could design your own transceiver to plug into the Flight Module it would require a substantially lower profile than the MHX transceiver What programming background does the CubeSat Kit require You should be comfortable programming microcontrollers in C Some experience with programming paradigms beyond the simple foreground background loop is helpful What kind of software does the CubeSat Kit include The Flight MCU comes pre programmed with a basic skeleton application that will get you started It s based on the Salvo RTOS to make it easier for users to manage the multitude of things the Flight MCU will be called upon to do All application source code in C is included UM 3 Pumpkin CubeSat Kit User Manual 43 The RTOS that runs in tiny places 44 User Manual What are the advantages of this RTOS based software approach RTOS based programming is one of the dominant programming pa
45. ule in Slot 1 15mm standoffs are used between adjacent user modules 12 9 5 i HU i 1 H SLOT 4 15 0 i SLOT 3 15 0 SLOT 2 15 0 SLOT 1 MHX Modem 25 0 i H HO H SLOT 0 ri l 4 5 LC Figure 3 Flight Module MHX Transceiver 4 User Modules 3 Flight Module MHX Transceiver User Module 3 PC 104 Modules In this configuration with the user module between the Flight Module and up to 2 PC 104 modules the user module is likely to implement a bridge between the CubeSat System Bus and the PC 104 bus The bridge must at a minimum connect the 5V and GND signals of the CubeSat System Bus to those of the PC 104 bus A configuration like this may or may not have an additional processor on the PC 104 modules 4 Flight Module 2 User Modules 2 PC 104 Modules In this configuration two user modules are located between the Flight Module and the PC 104 modules The lower Slot 1 user module can interface solely to the Flight Module via the CubeSat UM 3 Pumpkin CubeSat Kit User Manual 11 The RTOS that run s in tiny places User Manual System Bus whereas the upper Slot 2 user module is likel
46. upplies are normally tailored to the CubeSat s payload and processor s want to run Linux in my CubeSat Is the CubeSat Kit compatible The Flight MCU is much too small to run Linux However there are many off the shelf PC 104 modules with processors that are capable of running Linux So just pick one and put it in your CubeSat Kit UM 3 Pumpkin CubeSat Kit User Manual 37 The RTOS that runs 38 User Manual plan on running both a PC 104 SBC and the Flight Module s MCU in a dual processor configuration How can interrupt the Flight MCU from the SBC The MSP430 Flight Module accepts the RESET signal from the CubeSat System Bus This signal can activate the RST NMI signal The MSP430 Flight MCU can be configured in software to treat the RST NMI signal as a non maskable interrupt Are the 244 interface chips really necessary Yes Without them the Flight MCU could be subjected to overvoltages on its inputs leading to damage The type of interface chips and the overall circuit topology has been carefully chosen to eliminate any chance of damage to the Flight MCU from the 5V based USB to serial converter and MHX transceiver in any powered or unpowered state Additionally the interface chips guarantee the correct logic level signals when the Flight MCU is connected to either interface Why does the Development Board have an RS 232 connector To facilitate your CubeSat development For example you might decide
47. ve LOW P6 4 RI _USB USB s Ring Indicator input Active LOW P6 5 RST_USB USB s Reset input Active LOW Table 8 Flight MCU to USB Interface Signals 7 USB 2 0 compatible UM 3 Pumpkin CubeSat Kit User Manual 21 The RTOS that runs in tiny places Bit Bang Mode MHX Transceiver 22 User Manual The USB interface chip s bit bang mode is supported In this mode data can be read and written as parallel data on the FT232BM s serial I O pins with the following restrictions i i Bit Bang Function s Serial I O Pin Bit Bang Pin Supported TXD DataO Output only RXD Data1 Input only RTS Data2 Output only CTS Data3 Input only DTR Data4 Output only DSR Data5 Not supported DCD Data6 Not supported RI Data7 Input only Table 9 FT232BM Bit Bang Mode Pin Functions The output only and input only restrictions arise because U1 is not a bidirectional device and not all of the FT232BM s 8 bit bang pins are connected through U1 to the MCU An interface to accept an off the shelf 2 4GHz Spread Spectrum transceiver is provided This interface is powered by 5V and may draw substantial power from the CubeSat The Flight MCU sees the transceiver as Data Communications Equipment DCE The transceiver H5 is isolated from the Flight MCU bus via the buffers U2 and U3 When the Flight MCU wishes to transmit or receive it enables the transceiver interface by taking P6 6 LOW This power
48. very excited to be involved in a space related project and are eager to see the CubeSat Kit deployed into space Additionally Pumpkin is eager to promote Salvo as the premier RTOS solution for embedded single chip microcontrollers Salvo The RTOS that runs in tiny places Figure 2 Salvo Tagline Salvo is a perfect fit for the CubeSat s microcontroller i e its brains Salvo fits in the smallest and lowest power microcontrollers thus keeping the electronics well within the tight mass and power constraints placed on each CubeSat Also programming a CubeSat in C with an RTOS should substantially shorten development times compared to other programming methodologies The CubeSat Kit contains The RTOS that runs in tiny places User Manual e Mechanical assembly top and bottom covers sides and feet e Flight Module with Flight MCU e Development Board with Flight MCU header board and prototyping area e External benchtop 5V power supply e Debugging and programming interface e Miscellaneous parts e g spacers switches USB cable etc e Salvo RTOS e Documentation engineering drawings schematics etc As a CubeSat Kit user it s up to you to supply e Power source e g batteries and or solar cells e Custom user PCBs if required e Communications equipment e g radio antenna e Additional PCBs for your own electronics if required e Additional mechanical electrical and other components e
49. y to implement a bridge between the CubeSat System Bus and the PC 104 bus The bridge must at a minimum connect the 5V and GND signals of the CubeSat System Bus to those of the PC 104 bus ggg ttt aH o np U AOMML MOLALLA SLOT 2 SLOT 1 15 0 lq elie N SLOT 0 Figure 4 Flight Module 2 User Modules 2 PC 104 Modules 5 Flight Module 4 PC 104 Modules This configuration lacks a direct means of interfacing the Flight Module s Flight MCU with the PC 104 modules However it is conceivable that the two might be connected by a wire harness between one or more PC 104 modules and the CubeSat System Bus connectors on the Flight Module Note Due to clearance issues a PC 104 module cannot occupy Slot 1 if the MHX transceiver is fitted to the Flight Module 6 Flight Module 4 PC 104 Modules 1 Low Profile User Module 12 This configuration lacks a direct means of interfacing the Flight Module s Flight MCU with the PC 104 modules However it is UM 3 Pumpkin CubeSat Kit User Manual The RTOS that runs in tiny places User Man ual Sm
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