MICRO-GUIDER III - Nova Astronomics
Contents
1. C2 MEMORY L e AE f 22p LXI EE vec LU sv CB vec D sv C3 12M288 A 9 R A 9 A L U2 SC US 11 D Sri U6 11 o 2 ops c k 68 a T 00 A3 7 o0 22p GF 3 vm FD Je as A 6 a ot SL A 6 A o 12 Si v A ee A5 5 02 AS 5 02 Ut vv wo TT ADDRESS DECODING Lo IER Fees oa 15 D e GE T ee yR uR Si S RES E ag ag AS os DI D ag o7 AS os 18 D 4 HOM B15 NTS P U3 ao a per o7 U8 D A10 21 o g7 18 02 poe A 23 A 4 15 Att An pi Di DU Ce Ae a2 EE A EAN o mD 10K PiNaoot 100K INTZ DREGT PS sy A al 1 igr 9000 A ZE Ma WR Go WR ANS 28 An VPP 55 WR 13 57 A2 2 H TE TE An aal ST ckS Gen PAETA A14 i A14 E SS de U1 Al 15 Ri Ge eh MIRE 4d 1 pantie GND end 4 C1 i ES 18 a2 eno Ss ANS Zog 5 px 62256 270256 d 3 ba za 52 r x8 E3 6 pox osoooH 0000 10u 74HC14 a Zei A4 Tou Gi 7 biz AG 21 AS DREO Ge 74HC138 Sa RxAO He RXO SPAREGATES LZ fe Se o gt EE A9 24 ES A9 TTo E U1 12 AIT Se ae RTSO and D7 EoH 8 D I a7 At Deag ENCODER INTERFACE St A13 28 RE ES 42 D5 U4 Ui aea os n ZG An ccs RS232 INTERFACE o 40 A16 ai AS D3 Ge D2 AG SCH 1 Pig U11 E Ri EOH a A17 32 A16 D2 Ge D1 ge 2 Gs 5V E UM 5V A18 sel A17 Dt e DO OR 4 lee Do 3 3 A18 Do E1 4 Qo Do Z J4 CHARA SE 5v 4 veo ent Ve A3 5d2. Ep 5 pox Hi 5a Di 4 Zu CHB RA F U1 7 Gnos Gi A7__6 63 6 pS Eon D tae v2 Hx ae ipo o7 SA CR SE Vv 74HC138 at VCC D5 15 s ps Di DEI 74HC14 HD64180RCP 8X DIS 1 D6 __16 og pe PZ Q J4 GND et MICROPROCESSOR De Ze ST 5 6 v U13 8 Ee TAHC14 8 R16 C18 v C2 can 100K MAX232 Es POWER REGULATOR FT 22u al 22u N wu 1 VeATT U12 POWER SUPPLY DECOUPLING 2 2 Zen Tan PO Fer 1 7805 _ 3 VBATT ei IN OUT 5V 13 12 Dun Je RIIN RIOUT RXO VBATT s C5 enp Lc6 1c7 c8 c9 c101c11 mu Je 8 8 R2 N noom 2 Pai GND GND Jefo EX Se Es GND M out 10u Tou Ton Tou T out T out 15 v FIGURE 1 MARCH 10 1992 RS232 INTERFACE MICRO GUIDER III WIRING DIAGRAM KS x CG AUGUST 19 1995 un a ao oO Q a a Zz nO N oO a a 4 J3 DB 9S Di AZIMUTH ALTITUDE ENCODER ENCODER 1 S2 SERIES 1 S2 SERIES MICRO GUIDER III CONTROLLER BOARD IN400 5V 1 CH A AZIMUTH CH B AZIMUTH J4 GROUND 1 2 3 5 CH A ALTITUDE 6 CH B ALTITUDE 9 J2 DB 9P FIGURE 2 E wire lead loops for i 2 Pie A7 RE 025 square pins EDETI der m 025 square pins on 100 centers 5 on 100 centers 5 ALL DIMENSIONS IN INCHES S1 S2 OPTICAL SHAFT ENCODERS DESCRIPTION The S1 or S2 series optical shaft encoder is a noncontacting rotary to digital converter Useful for position feedback or manual interface the encoder converts realtime s
3. the complete MGIII is about 30mA plus the current used by the encoders the US Digital encoders consume about 17mA each This will provide several hours operation from a standard 9V battery use a 12 volt 6 amp hour gel cell battery which provides power for about a season of observing SOFTWARE As mentioned above the MGIII is basically a dedicated computer thus the software reflects greatly in its functionality The software was written in a combination of the C programming language and assembly language An important part of the software is the encoder routines written in assembly language The optical encoders are read by the software at a rate of 8000 times per second Each optical encoder produces two signals which are used to determine the motion including the direction of each telescope shaft The software interprets these signals to determine the azimuth and altitude of the telescope The remaining part of the program is the interface with the RS232 port The port is configured at 9600 baud eight data bits and one stop bit This portion is written in C There are several commands supported The main command Q queries the MGIII to transmit the current telescope position It responds immediately by sending the azimuth and altitude out the RS232 port to the connected computer The format transmitted is shown below 00123 lt tab gt 00456 lt cr gt where 00123 is the azimuth lt tab gt is an ascii tab char
4. MICRO GUIDER III A Telescope to Computer Interface Device You Can Build by David Lane Nova Astronomics updated June 16 1997 INTRODUCTION The Micro Guider III MGIII is a telescope to computer interface device based on my previous project the Micro Guider The original Micro Guider is a self contained device which provides a telescope with digital setting circles complete with a database of almost 8 000 celestial objects including the Messiers and the NGCs It interacts with the user using an LCD display and a 16 button keypad A detailed multi part article entitled M ICRO GUIDER I A Computerized Setting Circle Database Device You Can Build was published in Observatory Techniques 6 and 7 Summer and Fall 1993 The MGIII is a scaled down version which reads the telescope s azimuth and altitude and transmits it to a suitable computer program upon request This article will describe the MGIII s hardware software and construction It is the author s intent to provide enough information here to allow the electronics inclined telescope maker to build the device themselves To aid in building the MGIll the author has available a supply of blank printed circuit boards and the programmed EPROM chip needed to complete the device Some other components may also be available DESCRIPTION The MGIII is a device which connects to a telescope by using two optical encoders one attached to each axis of rotation The optica
5. acter decimal 9 00456 is the altitude lt cr gt is an ascii carriage return character decimal 13 The resolution of the encoders define the range of output expected in the azimuth and altitude readings H 4000 count encoders are used the range of output is 2000 to 1999 representing the angles 180 to 180 degrees Several other commands can be sent to the MGIII for such functions as setting the encoder resolution determining the number of encoder errors if any etc Determining the right ascension and declination of the telescope is quite complex and is calculated by the PC computer connected to the MGIII The algorithm which The Earth Centered Universe uses is described in an article published in the Astronomical Computing column of the February 1989 Sky and Telescope magazine CONSTRUCTION The construction of the MGIII is quite straight forward The parts list shown below lists all the materials necessary to build the MGIII Most are available from mail order outlets which cater to the hobbyist consult the advertisements in a recent electronics hobbiest magazine If materials sourcing proves difficult the author is willing to assist the prospective builder Many of the actual components listed in the parts list are only suggestions and many substitutes are possible The total cost of the parts is approximately 200US including the two optical encoders The hardware for mounting the encoders to the telescope axis will not b
6. anel Thickness 125 in max ELECTRICAL SPECIFICATIONS B leads A in a clockwise shaft rotation and A leads B in clockwise shaft rotation viewed from the mounting surface side of the encoder ACCESSORIES Cables and Connectors ORDERING INFORMATION U S Digital Corp 3800 N E 68th St Suite A3 Vancouver WA 98661 1353 800 736 0194 206 696 2468 Fax 206 696 2469 http Awww usdigital com FOR MORE INFORMATION VISIT THE US DIGITAL WEB SITE http www usdigital com
7. e discussed here since every telescope will require different mounting hardware The circuit board should be populated according to the silkscreen markings on the PCB Be careful to note the polarity of the diodes and capacitors and the orientation of the integrated circuits Be particularly careful with U2 and its socket Only install the components identified in the parts list All of the other components are not required since they are used only by the original Micro Guider which has a real time clock an LCD and a keypad Components U2 and U6 should be socketed The remaining IC s can be socketed if desired The chassis wiring can be performed using ribbon cable as have used following the wiring diagram shown as Figure 2 PARTS LIST Resistors leet 10K 0 25W 5 R12 RIO eei ei e r aie 100K 0 25W 5 Capacitors EA e 10uF 25V tantalum 0 2 lead spacing E Ee KEE 0 1uF 50V ceramic 0 2 lead spacing C2 EE 22pF 50V ceramic 0 2 lead spacing LF af d e Be WE 22uF 16V tantalum 0 2 lead spacing Semi Conductors X EE 12 288MHz crystal HC 18 U case style Dl E 1N4001 diode MIT BEEN 74HC14 IC ee ee Hitachi HD64180RCP 8X or Zilog Z8018006VSC microprocessor Available from the author for 10US ab EEN 74HC138 decoder Web Hitachi HM62256LP 12 32K static RAM eegene 27C256 EPROM Programmed available from the author for 15US pb 74HC373 IC Oh EE 7805 IC TO 220 case NDT eegener eebe Maxim MAX232CPE IC Miscel
8. haft angle speed and direction into TTL compatible quadrature outputs with or without index The encoder utilizes an unbreakable mylar disk metal shaft and bushing LED light source monolithic electronics and operates from a single 5 volt supply Available with ball bearings for motion control applications or torque loaded to feel like a potentiometer for front panel manual interface FEATURES Small size Low cost 2 channel quadrature TTL square wave outputs 3rd channel index option Tracks from 0 to 100 000 cycles sec Ball bearing option tracks to 10 000 RPM 40 to 100eC operating temperature Single 5v supply MECHANICAL SPECIFICATIONS All Options Vibration 20 g 5 to 2KHz max Acceleration 250 000 rad sec2 max Sleeve bushing non ball bearing Shaft Speed 100 RPM max continuous Shaft rotation Continuous and reversible Shaft torque 0 5 0 2 in oz 0 3 in oz max NT option Shaft loading 2 lbs max dynamic 20 lbs max static Weight 0 7 oz Shaft runout 0015 T I R max Ball Bearing Option Shaft Speed 10 000 RPM max continuous Acceleration 50K Rad Sec2 10K Rad Sec2 SP 1000 Series Shaft torque 0 05 in oz max Shaft loading 1 Ib max Bearing Life 40 P 3 Life in millions of revs where P radial load in pounds Weight 0 7 oz Shaft runout 0015 T I R max MATERIALS Shaft Brass or Stainless Bushing Brass Connector Gold plated MOUNTING Hole Diameter 380 in P
9. l encoders translate the rotational movements of the telescope into electrical signals which are interpreted by the MGIII s on board microprocessor The current position of the telescope is transmitted to a computer upon request using a standard RS232 interface The MGIII is used in conjunction with a suitable computer program which can translate the telescope s coordinates into right ascension and declination and act as an aid in locating objects at the eyepiece preferably in a graphical way The MGIII is designed to be compatible with the author s shareware Planetarium and Telescope Control Program for Microsoft Windows The Earth Centered Universe ECU It is also compatible with other programs ECU provides the interface between the telescope the MGIII and the user will not discuss the operation of ECU in this article since the operating procedures are documented in ECU s User s Manual As is normal practice with modern digital setting circles the MGIII will work equally well with equatorial or alt azimuth mounted telescopes since it does not require polar alignment or mount levelling Once aligned ECU provides all the necessary mathematical conversions to use the elapsed time and the azimuth and altitude from the MGIII to calculate the current right ascension and declination To initialize the system ECU asks the user to point the telescope at two stars Polar aligned equatorial telescopes need to be aligned on only
10. laneous d satan E E E E E E E E EE atten printed circuit board Available from the author for 35US UE 68 pin PLCC socket for U2 E 28 pin IC socket for U6 SEENEN 10 contact double row straight male headers for J4 J6 0 1 pin spacing UR suitable enclosure E US Digital Corp S1 1000 0 09 degree resolution optical encoders Phone 800 736 0194 or 206 696 2468 Bee DB 9P connectors EES DB 9S connectors ileal ele cate tend eege 10 pin IDC ribbon cable connectors eege encoder mountings telescope specific RS232 cable to PC straight through wiring DB 9S to DB 9P Assorted wire and ribbon cable Assorted hardware CONCLUSION The MGIII provides an inexpensive and easy to build digital setting circle device The author s inexpensive shareware program for Microsoft Windows The Earth Centered Universe ECU provides full support for the MGIII and many other telescopes ECU a full featured planetarium and telescope control program is available from the author for 50US The shareware version is available here David J Lane Nova Astronomics PO Box 31013 Halifax Nova Scotia Canada B3K 5T9 Phone 902 443 5989 evenings Fax 902 445 5790 Compuserve ID 71601 247 E mail dlane hercules stmarys ca MICRO GUIDER III CONTROLLER BOARD
11. one star HARDWARE The MGIII s hardware consists of one printed circuit board the same one used in the original Micro Guider except with fewer components installed The schematic diagrams of the circuit board are depicted in Figure 1 The chassis wiring interconnecting the circuit board and the other components is shown in Figure 2 This section provides a brief description of how the MGIII works however it is not required for the reader to understand how the hardware works to build the device The architecture of the MGIII is based on Hitachi s HD64180 microprocessor This microprocessor is a highly integrated version of the older Zilog Z80 microprocessor Components C2 C3 X1 comprise the main oscillator which is used to time all functions of the computer U6 is the EPROM chip 32k bytes which is used to store the MGIII s software U5 provides 32K bytes of RAM for use by the software Not all of this RAM is used in fact an 8K byte device is sufficient The components mentioned in the previous paragraph form a complete fully operational computer But a computer by itself with no input output is all but useless U11 is used to read the outputs from the encoders Components U13 and C17 C20 are used to provide the RS232 interface U12 is used to regulate positive five volts which powers all of the circuitry The minimum operating voltage is seven volts but it will operate properly up to at least 15 volts The current consumption of
Download Pdf Manuals
Related Search