Chapter 5: Peripheral devices and programming experiments
Contents
1. td1 address_x 0x00 if td1 address_x 0x00 wrong_tag 1 phex 16 address_x if wrong_tag 0 putchar 0x3d equal sign putchar Ox4f o putchar 0x4b k putchar 0x0a new line putchar 0x0d carraige return else putchar 0x3d equal sign putchar 0x46 46 F putchar 0x41 41 A putchar 0x49 49 I putchar 0x4c 4c L putchar 0x0a new line putchar 0x0d carraige return Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a phex16 wrong_tag putchar Ox0a putchar 0x0d return wrong_tag main unsigned char wtag1 wtag2 wtag3 wtag4 test and show result using LEDS wtagl testl_xram_0000_7fffO wtag2 test2_code_xram_9000_dfffQ test and show result using serial out wtag3 test3_com_out_xram_0000_7fffQ wtag4 test4_com_out_code_xram_9000_dfffQ if wtagl 0 amp amp wtag2 0 amp amp wtag3 0 amp amp wtag4 0 putchar 0x41 A putchar Ox4c L putchar Ox4c L putchar 0x20 space putchar Ox4f O putchar Ox4b K putchar Ox0a new line putchar Ox0d carraige return else putchar 0x46 46 F putchar 0x41 41 A putchar 0x49 49 I putchar 0x4c 4c L putchar 0x0a new line putchar 0x0d carraige return 5 16 Conclusion In this chapter we have studied the use of interrupt2. correct for test1 ram0000 7fff else p8255_e000_a Oxff 0x01 error for test 1 ram0000 7fff return wrong_tag test2_code_xram_9000_dfffQ p8255_e800_cnt 0x80 port a b c all outputs for Cachecom 803 Irl sbc board system code eprom O0x0000 gt 0x7fff is at US 27256 32K eprom data XRAM 0x0000 gt 0x7fff is at U6 62256 32K sram code data XRAM 0x8000 gt Oxdfff is at U7 62256 32K sram test 1 xram 0x0000 0x7 fff wrong_tag 0 for address_x 0x9000 address_x lt Oxdfff address_x tdl address_x Oxff if td1 address_x Oxff wrong_tag 1 tdl address_x 0x00 23 Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a 24 if td1 address_x 0x00 wrong_tag 1 if wrong_tag 0 p8255_e800_a Oxff 0x85 correct for testl ram0000 7fff else p8255_e800_a Oxff OxOf error for test1 ram0000 7fff return wrong_tag external phex16 of Paulmon2 void phex16 unsigned int ii _asm push DPL push DPH push R2 push R3 push R4 push R5 push PSW _endasm DPL ii 256 DPH ii 256 _asm Icall 0x0036 _endasm _asm pop PSW pop R5 pop R4 pop R3 pop R2 pop DPH pop DPL _endasm external _pucthar function expected by serial h used in Paulmon2 include lt reg51 h gt needed ACC is the accumulator char getch char cin _asm push AC
3. Figure 5 8 The main program and an interrupt service routine So what is an interrupt source For the 8031 processor an interrupt source is a condition that the 8031 will execute an interrupt service routine ISR if such a condition occurs There are 5 such sources as shown in the table below and each source is associated with an interrupt vector which is the beginning address of that ISR 5 6 Interrupt handling in 8031 and interrupt service routines ISR There are altogether 5 sources of interrupts to the 8031 Interrupt type Description Vector Address Signal pin at the 8031 0 External 0 0x0003 pinl2 INTO or P3 2 1 Timer 0 0x000B internal 2 External 1 0x0013 pinl3 INT1 or P3 3 3 Timer 0x001B internal 4 Serial 0x0023 internal Table 5 2 The 5 8051 interrupts and their vector addresses Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a Serial IO when a valid data is received or when a valid data is transmitted Interrupt service routine ISR with the name name_isrO responses to external interrupt intO pin 0 pin12 p3 2 using register bank 2 void name_isr0 interrupt 0 Main program using 2 Maino Triggered by Hardware A C view of external int0 Will inset an reti return reti return from interrupt assembly instruction here by the compiler from interrupt Figure 5 9 A C view of external intO When an interrupt condition appears
4. every minures at the first 3sec rtc_ec03_minute_alarm Oxff minute is don t care rtc_ec05_hour_alarm Oxff hour is don t care for reference only interrupt case 2 every second type rtc registers rtc_ecOa_rega 0x20 rtc_ecOb_regb 0x10 foo rtc_ecOc_regc make sure pin19 of ds21287 irq 1 Anterrupt case 3 periodic interrupt rtc registers setting ttc_ecOa_rega 0x23 for 8192Hz 0x24 for 4096Hz 0x25 for 2048Hz 0x26 for 1024Hz 0x27 for 512 0x28 for 256Hz 0x29 for 128Hz 0x2a for 64Hz 0x2b for 32Hz 0x2c for 16Hz 0x2d for 8 Hz Ox2e for 4Hz 0x2f for 2Hz rtc_ecOa_rega 0x2d 0x20 for slower 1 s b 4bit rate rtc_ecOb_regb 0x40 foo rtc_ecOc_rege make sure pin19 of ds21287 irq 1 forG 0 1 lt 100 i for a 0 a lt 10000 a realtime clock testing time 1 rtc_ec00_second read in second p8255_e000_a Oxff time1 for a 0 a lt 10000 a p8255_e000_a Oxff time1 use interrupt 0 external intO pin12 of 8031 reg bank 2 for the following statement 2 is interrupt number fusing 2 means register bank 2 void ext_int_isr2 void interrupt 0 using 2 register bank 2 p8255_e800_a Oxff pattern_count pattern_count pattern_count 1 make sure pin19 of ds21287 irq 1 foo rtc_ecOc_regc read it once to off interrupt 5 13 Experiment 44 Use of putchar and getch with some bug test44 c This experiment tests the use of f
5. from one of the five interrupt sources and the system is programmed to allow such interrupt by setting some bits in the IE TP and TCON registers of the 8031 to occur e Wait until the current instruction is finished Note that PSW the flag register ACC and other registers are not saved the programmer needs to do the pushing and popping of registers explicitly as contrast to the 80x86 which would do pushing and popping of general registers automatically during ISR calls e Push the program counter to the stack so that it knows how to comes back e Reload the program counter with the interrupt vector according to the source for the interrupt e So it will execute the corresponding ISR when the 8031 executes an RETI instruction in the ISR it will pop the main program return address from the stack and return to the main program For each ISR call it will jump to that particular address when the current instruction is completed The starting address corresponding to each interrupt request or called interrupt vectors is hardwired that means you cannot change it However if some other places are more convenient you may simply redirect it to other locations by a long jump instruction For example by putting a ljump 8013H at the starting address of particular the ISR vector say 0013H it will finally reach 8013H as a result of that interrupt request Interrupt enable register You may program the 8031 to accept or ignore cer
6. compiler does not care so you need to check for yourself after you run the program 1 led at e000 LEDs turned on means wrong 2 leds at e000 LEDs turned on means correct This program writes data into sram and read it back and see Af it is ok or not include lt 8051 h gt include lt stdio h gt xdata unsigned char td1 Oxffff from 0x8000 gt 0x7fff long long_i int i j unsigned int address_x unsigned char foo wrong_tag xdata unsigned char p8255_e800_cnt 0xe803 xdata unsigned char p8255_e800_a 0xe800 xdata unsigned char p8255_e800_b 0xe801 xdata unsigned char p8255_e800_c 0xe802 xdata unsigned char p8255_e000_cnt 0xe003 xdata unsigned char p8255_e000_a 0xe000 xdata unsigned char p8255_e000_b 0xe001 xdata unsigned char p8255_e000_c 0xe002 test1_xram_0000_7fffQ p8255_e000_cnt 0x80 22 Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a for Cachecom 803 Irl sbc board system code eprom O0x0000 gt 0x7fff is at US 27256 32K eprom data XRAM 0x0000 gt 0x7fff is at U6 62256 32K sram code data XRAM 0x8000 gt Oxdfff is at U7 62256 32K sram test 1 xram 0x0000 0x7 fff wrong_tag 0 for address_x 0 address_x lt O0x7fff address_x td1 address_x Oxff if td1 address_x Oxff wrong_tag 1 td1 address_x 0x00 if td1 address_x 0x00 wrong_tag 1 if wrong_tag 0 p8255_e000_a Oxff 0x85
7. interrupt testing program test 42 c Objectives and aims This experiment is design to help students to learn the use of interrupt in a microprocessor system The testing program has two parts one main and the other an ISR The students will see how an hardware interrupt will trigger the SBC to execute a particular ISR upon the request of an external source and jump back to the main program afterwards What does test42 c do The following program has two parts the main and the interrupt service routine ext_int_isr2 The main program blinks the LEDS of the SBC and when int pin13 of the 8031 is pulled low ext_int_isr2 void will be executed which sets the LEDS to a different pattern By doing so we can see that the ext_int_isr2 void is actually being run Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a 14 Test42 c When int1 is ext_int_isr2 Main setup interrupt Blinks the LEDS Figure 5 11 The main and ISR of the testing progam Testing procedures 1 Compile test_isr2 c using SDCC and download the program to the SBC using Windows Hyperterminal and Paulmon2 commands 2 Run the program by jumping to 0x8000 3 We know that when we connect int pin 13 of the 8031 to ground then ext_int_isr2 void will be executed So for the experiment wire wrap pin13 of con3 with a thin wire and connect it to GND of con2 when test4 2 c is being run Note the schematic of
8. you up by pressing the reset 8051 Sends regular signals to the watch Reset Q dog timer Button WATCHDO MAX691 Figure 5 4 To illustrate how the watch dog timer works Real time clock DS1287A See ds12887 pdf ds1287A is an old version of ds12887 so read ds12887A data sheet instead A real time clock with an internal battery to keep it running gives you the time readings including years months days hours minutes and seconds Not only does it give you the correct time it can also generate accuracy clock signals for various control functions Also some real time clock chips have batteries inside that enable the chips to run for 10 years 5 4 The add on card concept This little 8031 is wonderful but not without limitations For one thing one of the two 8031 internal timers would be used by the serial link for generating Baud rates Since timer is so important in our robot design for generating pulse width modulation signals for driving DC motor or servo positional motor we do need more timers for our disposal Another thing is the 8031 itself is heavily loaded with peripheral chips such as two 8255s and ROM RAMS etc if more devices are to be added the 8031 outputs pins may not be able to deliver enough currents for proper operations One way to get round it is to attach devices at the output side of the 8255 It is as if an external bus is developed for add on cards just like a PC If we carefully design the hardwar
9. 0x85 a very important step to initialize interrupt in the 8031 set interrupt pin intl active low pin13 of 8031 TCON TCON 0x01 init 8255 A cnt 0x80 all outs 0x89 gt PA in low_PC in high_PC input pb out p8255_e800_cnt 0x80 p8255_e000_cnt 0x80 off all leds at p8255_e000 p8255_e000_a Oxff main_pattern 0xOf for i 0 1 lt 20 i a long loop for a 0 a lt 50000 a p8255_e000_a main_pattern for a 0 a lt 50000 a p8255_e000_a Oxff main_pattern use interrupt 2 external interrupt 1 pin13 of 8031 using register bank 1 note use interrupt 2 external interrupt 1 pin13 of 8031 using register bank 1 for the following statement 2 is interrupt number using means register bank 1 if you use sdcc isr5 c code code 0x8000 main return this ISR will be at 0x8013 in Paulmon2 at 0x0013 long jump Imp to 0x8013 address code jump from 0013 to 8013 0013 02 long jump ljmp 0014 80 0015 13 it seems that if using 1 is used it cannot goes back to paulmon2 it seems that if using 2 is used it can goes back to paulmon2 void ext_int_isr2 void interrupt 2 using 2 register bank 2 isr_pattern p8255_e800_a isr_pattern 5 12 Experiment 43 Using the real time clock Dollas DS1287A test43 c Students should learn about the programming of the real time clock DS1287A ds12887a pdf before running this lab 15 Mobile Robot chapter 5 Periph
10. 8231RL is confusing the following pin assignment is easier to read and is correct 8031SBC RS232 Pin 12 of con3 aa ess TJ ores of 8031 Pin 13 of con3 is intl pin 13 of 8031 Figure 5 12Showing the connection of the external interrupt pin 4 Record what you see a before b during and c after int1 is pulled low Explain the result Exercise When int1 is low and high again we observed that the LEDS of p8255_e800 always have a new pattern explain why Program listing test42 c test42 c ver3 12 contains main and ISR for external int1 pin13 when int1 pin13 is low ISR ext_int_isr2 void will be executed Compile command line gt sdcc main return code loc 0x8000 test42 c include lt 8051 h gt int i a temp main_pattern is used in the main prog isr_pattern used in the ISR unsigned char main_pattern isr_pattern setup 8255 register pointers xdata unsigned char p8255_e800_cnt 0xe803 Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a xdata unsigned char p8255_e800_a 0xe800 xdata unsigned char p8255_e800_b 0xe801 xdata unsigned char p8255_e800_c 0xe802 xdata unsigned char p8255_e000_cnt 0xe003 xdata unsigned char p8255_e000_a 0xe000 xdata unsigned char p8255_e000_b 0xe001 xdata unsigned char p8255_e000_c 0xe002 main SETUP INTERRUPT fe 7 global enable interrupt set ie 2 external int 1 set ie 1 external int 0 set TE IE
11. C _endasm _asm Icall 0x0032 Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a 25 _endasm cin ACC _asm pop ACC _endasm return cin void putchar char cout ACC cout _asm Icall 0x0030 _endasm delay xdata unsigned int delay_t xdata unsigned int long del_x del_y del_fool for del_y 0 del_y lt delay_t del_y for del_x 0 del_x lt 20 del_x del_foo1l 0 test3_com_out_xram_0000_7fffO wrong_tag 0 for address_x 0 address_x lt Ox7fff address_x td1 address_x Oxff if td1 address_x Oxff wrong_tag 1 td1 address_x 0x00 if td1 address_x 0x00 wrong_tag 1 phex 16 address_x if wrong_tag 0 putchar 0x3d equal sign putchar Ox4f o putchar Ox4b k putchar Ox0a new line Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a 26 putchar Ox0d carraige return else putchar 0x3d equal sign putchar 0x46 46 F putchar 0x41 41 A putchar 0x49 49 I putchar 0x4c 4c L putchar 0x0a new line putchar 0x0d carraige return phex16 wrong_tag putchar Ox0a putchar 0x0d return wrong_tag test4_com_out_code_xram_9000_dfffO wrong_tag 0 for address_x 0x9000 address_x lt Oxdfff address_x td1 address_x Oxff if td1 address_x Oxff wrong_tag 1
12. Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a Chapter 5 Peripheral devices and programming experiments Objectives Study the functions and operations of various peripheral devices of the 8031 based computer Learn to program peripheral devices of the 803 1 based computer Learn to use interrupt programming techniques 5 1 Introduction In this chapter we will first give an overview of the structure of the 8031 SBC card then we will describe the functions and operations of each peripheral device Programming exercises for these devices will also be introduced Finally the hardware and software techniques on Interrupt will be explained in detail 5 2 Overview of the 8031 SBC The 8031 SBC board you use is a low cost yet a powerful and comprehensive controller card it has the following interface modules The 8031 has timers and supports two external interrupt inputs Two 8255 chips on board will give you 48 bits of parallel IO bits Serial interface to talk to your PC through a MAX232 RS232 interface chip One watch dog timer MAX691 One real time clock DS1287A to keep time and generate interrupt Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a 8031 SBC Parallel 48 digital IO pins Real time clock DS1287A Two 8255 n bus T connectors 7 7805 regulator LCD CONNECTOR Figure 5 2 Picture of th
13. Oxe000 p8255_e000_a 0x00 will turn on all LEDS at port A of 8255 at Oxe000 Procedures Download from PC to 8031 sbe 1 Connect 8031 sbe to com2 using an RS232 serial cable 2 Run Win98 Hyperterminal from PC by double click Windows Hyperterminal from explorer In Windows Hyperterminal Transmit Text is a useful commands In Windows Hyperterminal Set 9600 N 8 1 com2 etc use Alt p to set communication parameters Press reset at the 8031 sbc You will see the message of Paulmon2 message on the screen paulmon http www pjrc com tech 805 1 index html In Paulmon command windows Press to see the available commands In Paulmon command windows D for download 0 Now you are back to Windows Hyperterminal press Alt S select ASCII for sending test41 ihx 11 You will see then get a message of download complete 12 Since the code is actually in 0x8000 so you can read the code or assembly disassembled by Paulmon 2 I think try N 8000 then L for viewing assembly code or H for viewing hex code 13 Use yj 8000 to jump to the start address of the executable code test41 ihx you just downloaded 14 The LEDS of 8031 sbc should blink and after a few seconds when the program terminates Paulmon2 goes back to its starting point again 15 Done Eo OND Exercise e Program the LEDS at 0xe800 to have a pattern of 0x01 and rotates this pattern crosswise or anti clo
14. TERRUPT 2 gt external int2 pin 13 of 8031 when int1 pin 13 of 8931 is low 8031 will execute this ISR ISR interrupt number 2 using register bank 3 void your_isr2 void interrupt 2 using 3 does something ISR does an reti instruction will be automatically added here by the compiler 5 8 Redirection oif ISR vectors in Paulmon We will see how Paulmon redirects ISR vectors to the RAM2 space Since Paulmon2 our 8031 monitor program at EPROM resides at 0000 7FFFH 8K locations of the program address space therefore when any interrupt request occurs it will execute some code inside Paulmon2 namely 0x0003 0x000B 0x0013 0x01B and 0x23H As ISRs are inside UV ROM space it takes time to modify because it takes 10 Minutes to erase and reprogram an EPROM Hence development of ISRs becomes a time consuming process Therefore we prefer to put these ISRs in RAMS space i e RAM2 We can do this by carefully redirect the ISR vectors by using long jump jmp instructions The following is how PAULON2 redirect the ISR vectors SDCC ISR vector entry Paulmon2 s e interru e point of interrupt ROM gT Drone type 0 for external location interrupt _ begins at intO pin 12 8003H data prog Figure 5 10 Redirection of interrupt vectors As discussed before the SDCC C cross compiler actually puts the interrupt ISR vectors to a location relative the start address of the
15. a c t50_xdata c LED at p8255_e000 Ox85 gt no error 0x01 gt error at test1 LED at p8255_e800 0x85 gt no error OxOf gt error at test2 for Cachecom 803 Irl sbc board system code eprom 0x0000 gt 0x7fff is at US 27256 32K eprom data XRAM 0x0000 gt 0x7fff is at U6 62256 32K sram code data XRAM 0x8000 gt Oxdfff is at U7 62256 32K sram test1_xram_0000_7fffQ test2_code_xram_9000_dfffQ only two tests cannot test 0x8000 gt 0x8fff because this code will sit in Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a Program to show how to use 1 external 32K byte sram of the 8031sbe and 2 the compile option xram loc Hardware requirment 1 you must have the MAX691 watch dog on board 2 I suppect we can make it work even without the MAX691 the solution is when the max 691 is removed connect pin12 and 13 of the empty socket The test was performed but failed however we can think along this line refer to the circuit digram for the design of the board for futher investigations compile line gt Sdcc code loc 0x8000 xram loc 0x0000 main return test47 c or simply gt Sdcc code loc 0x8000 main return test47 c since defualt xram loc is Ox0000 In general for the 8031SBC rl you can use xram loc from 0x0000 to 0xd000 e g xram loc Oxc000 but your user program in RAM is usally at 0x8000 so try not to put two things at the same address the
16. ata unsigned char p8255_e800_a 0xe800 xdata unsigned char p8255_e800_b 0xe801 xdata unsigned char p8255_e800_c 0xe802 xdata unsigned char p8255_e000_cnt 0xe003 xdata unsigned char p8255_e000_a Oxe000 xdata unsigned char p8255_e000_b 0xe001 xdata unsigned char p8255_e000_c 0xe002 realtime clock ds1287 xdata unsigned char rtc_ecO0_second 0xec00 xdata unsigned char rtc_ec0O1_second_alarm 0xec01 xdata unsigned char rtc_ec03_minute_alarm 0xec03 xdata unsigned char rtc_ecO5_hour_alarm Oxec05 xdata unsigned char rtc_ecOa_rega OxecOa xdata unsigned char rtc_ecOb_regb OxecO0b xdata unsigned char rtc_ecOc_regc O0xecO0c xdata unsigned char rtc_ecOd_regd Oxec0d main SETUP INTERRUPT TE IE 0x85 fie 7 global enable interrupt set fie 2 external int 1 set fie lexternal int 0 set set interrupt pin intl active low pin13 of 8031 TCON TCON 0x01 init 8255 A p8255_e800_cnt 0x80 p8255_e000_cnt 0x80 p8255_e000_a Oxff p8255_e800_a Oxff pattern 0xOf read it once to make irq pin19 of ds1287 return to 1 foo rtc_ecOc_rege 17 Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a for reference only interrupt case 1 set rtc alram clock mode rtc_ecOa_rega 0x20 rtc_ecOb_regb 0x20 foo rtc_ecOc_regc make sure pin19 of ds21287 irq 1 rtc_ec01_second_alarm Oxff second don t care interpt every second rtc_ecO1_second_alarm 0x03 int
17. ator Endless loop read second counter and display through LEDS of Oxe000 ISR responses to periodic interrupt request through IRQ of the real time clock Increment a counter and show it to the LEDS at Oxe800 Procedures No need to make any hardware connection just compile the program download it and test But you need to use a DSO to observe the waveform of IRQ pin 19 of DS1287A Exercise e Modify the program to make the interrupt counter LEDS count faster it can be done by increasing the interrupt rate Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a e Use a DSO to observe the waveform of the interrupt request signal from the real time clock pin 19 of DS1287A and record the frequency is it what you would expected Program listing test43 c test43 c ver3 12 testing of the real time clock Dollas DS1287A or 12887A No need to make any hardware connection just compile the program download it and test Pin 19 of DS1287 is already connected to INTO pin 12 of 8031 SBC remember to set Interrupt pin active low at 8031 by TCON TCON 0x01 isrmain1 c blink LED of the cache 8051sbc computer compile command line gt Sdcc test43 c code loc 0x8000 main return include lt 8051 h gt include lt stdio h gt int i a temp unsigned char time1 foo unsigned char pattern pattern_count 1 xdata unsigned char p8255_e800_cnt 0xe803 xd
18. ch the use of the C development hardware software setup Students are required to show particular patterns of LEDS on the 8031 SBC What does test41 c do The program shown below first creates a pointer lists for the C programmers to address the 8255 control and data registers of the SBC There are two 8255 chips and each chip has 4 registers one control register and three data registers each for a 8 bit data port One 8255 chip is connected to the address begins at Oxe800 and the other at Oxe000 Because each 8255 occupies 4 locations so the address map becomes 8255 at Oxe800 8255at Oxe000 Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a 12 Oxe800 portA connected to LEDS 0Oxe000 portA connected to LEDS Oxe801 portB Oxe001 port B Oxe802 portC Oxe002 port C Oxe803 control reg Oxe003 control reg C pointers are used for addressing the hardware locations at the 8031 data space that is used for the 8255 chips In the header unsigned char xdata pointer name address_inhex e g unsigned char _xdata p8255_e800_cnt 0xe803 In the program what you have to do is to write to those locations as if they are variables by pointer access methods E g p8255_e800_cnt 0x80 will write 0x80 into the control reg of 0x8255 at Oxe803 The LEDS are connected to the port A of the 8255 devices so with revised convention p8255_e000_a Oxff will turn off all LEDS at port A of 8255 at
19. ckwise among the 8 LEDS at a rate about 2 new patterns per sec e Learn how to program the control registers of the 8255 parallel port to make portA out portB in upperC out lowerC in all in mode 0 Program listing test41 c test41 c ver3 12 contains main and ISR for external int1 pin13 when int1 pin13 is low ISR ext_int_isr2 void will be executed Compile command line gt sdcc main return code loc 0x8000 test41 c include lt 8051 h gt Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a 13 int i a temp main_pattern is used in the main prog unsigned char main_pattern setup 8255 register pointers xdata unsigned char p8255_e800_cnt 0xe803 xdata unsigned char p8255_e800_a 0xe800 xdata unsigned char p8255_e800_b 0xe801 xdata unsigned char p8255_e800_c 0xe802 xdata unsigned char p8255_e000_cnt 0xe003 xdata unsigned char p8255_e000_a Oxe000 xdata unsigned char p8255_e000_b 0xe001 xdata unsigned char p8255_e000_c 0xe002 main init 8255 A cnt 0x80 all outs Ox89 gt PA in low_PC in high_PC input pb out p8255_e800_cnt 0x80 p8255_e000_cnt 0x80 off all leds at p8255_e000 p8255_e000_a Oxff p8255_e800_a Oxff main_pattern 0xOf a long loop that blinks LEDS forG 0 1 lt 20 i for a 0 a lt 50000 a p8255_e000_a main_pattern for a 0 a lt 50000 a p8255_e000_a Oxff main_pattern 5 11 Experiment 42
20. desired code location For example if you 10 Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a 11 compile the program using the code loc 0x8000 the ISR vectors are relocated to the place starting at 0x8000 So PAULMON2 SDCC and 8031RL SBC are working in harmony For example compile line gt sdcc test_isr0 c code loc 0x8000 main return the following isr will be at 0x8003 test_isr0 c listing Iis shown below main setup interrupt endless loop ISR responding to an interrupt type 0 gt external int0 pin 12 of 8031 INTERRUPT 0 gt external intO pin 12 of 8031 when intO pin 12 of 8031 is low 8031 will execute this ISR ISR interrupt number 0 using bank 3 registers void ext_int_isrO void interrupt 0 using 3 does something ISR does 5 9 Descriptions of the experiments e Experiment 41 Use of 8255 parallel interface e Experiment 42 Use of Interrupt e Experiment 43 Use of the real time clock e Experiment 44 Use of printf and getch e Experiment 50 Use of xdata and serial port 5 10 Experiment 41 use of the 8255 parallel ports test41 c A simple test to get you familiar with the 8255 parallel ports of the 8031 SBC However students should study the datasheet of 8255 8255 pdf to learn how to program the 8255 control register and data ports for different IO modes Objectives and aims This experiment is design to tea
21. e it will give us a flexible platform for not just adding more timers 8253 but also more parallel ports 8255 or peripherals such as 8253s or Analog to Digital converters etc Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a 255 outputs ov add on Cards An 8031 SBC xw add on card slots Figure 5 5 A 8031 SBC with add on card slots added 8253 8254 interval timer http developer intel com design periphrl INDEX HTM Look for the data sheet of 8254 for it is a superset of 8253 It is a device to generate exact timing pulses for various applications One main usage is to produce pulse width modulated timing signals for the ultra sonic radar system the servomotor and the direct current motors for the robot 8253 timer Figure 5 6 8253 attached to the 8255 Exercise 5 1 The 8255 has three 8 bit IO ports total 24 bits Design the interface between the 8255 and 8253 Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a Figure 5 7 The pin assignment of 8253 5 5 Interrupt service routines and vectors of the 8031 What is hardware interrupt It is a method to ask the computer to execute a program interrupt service routine or ISR upon the reception of a request from an hardware interrupt source Main Interrupt request source setup interrupt signal doing something Interrupt service routine ISR vector reti return from interrupt
22. e 8031RL SBC 5 3 Introducing the Peripheral devices to be used with the 8031 In this section we will discuss the ways of how to use a number of different useful peripheral chips for the 8031 and illustrate how to utilize these devices through a series of experiments Datasheets of these chips can be found at http www cse cuhk edu hk khwong datasheets Parallel input output 8255s interface See http developer intel com design periphrl INDEX HTM for datasheet of 8255 The SBC has two 8255 chips Since each 8255 has 3 sets of 8 bit IO pins therefore each 8255 has 24 bit IO bits Thus the board has 48 bits of digital IO pins Programming of the 8255 can be found in the data sheet Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a To make the system useful and be able to control our robot it should have a set of parallel IO pins for our disposal The 8031 has originally come with a set of 32 IO pins however they are already used for memory interfaces and other important purposes such as serial IO timer etc It left very little IO pins for our control work One possible solution and a very popular one is to add one or two parallel interface chips 8255 to our system The interfacing work is quite standard and the 8031 micro controller has been designed to have the interfacing pins ready for the connection Such connection requires the host system a uP or an 8031 to control two address pins AO A1 8 bi
23. eral devices and programming experiments v 2a 16 Objectives and aims To learn about real time interrupt techniques In this experiment a real time clock is used to generate a periodic time interrupt to the CPU The advantage is to have control of the occurrence of certain events at precise timing What does it do 8031SBC 8031 Connected Real time clock already DS1287A pinl2 Pin19 IRQ output int0 Figure 5 13 The Real time clock generates a regular interrupt to the 8031 It is found that the IRQ pin19 of the DS1287 real time clock is already connected at factory to the external interrupt request intO pin12 of the 8031 Therefore if we can program the real time clock to send out interrupt request signal at a fixed time interrupt the 8031 will serve out request at a regular basis The DS1287A has two different output mode for output signals 1 to generate interrupt every second 2 to generate faster interrupt rate we will use case 2 in our experiment You can see that at the main program it reads the real time clock and display its time in seconds through the LEDS While in the ISR each triggering will make enable a counter to increment and the counter is also shown by the LED display Note that in the 8031 SBC the real time clock s address begins at Oxec00 Algorithm of Test43 c Main Initialize 8255 interrupt setup Initialize real time clock interrupt signal generation mode to pattern gener
24. ge return 3 message and c cannot mix e g printf Message oc cin_char does not work you have to make it to two lines such as printf message printf c cin_char 5 scanf is not implemented I think 6 Cannot print integer d floating point numbers are not supported officially include lt 8051 h gt include lt stdio h gt include lt serial h gt include lt stdlib h gt TTT TTT external _pucthar function expected by serial h used in Paulmon2 include lt reg51 h gt needed ACC is the accumulator char getch char cin _asm push ACC _endasm _asm Icall 0x0032 _endasm cin ACC _asm pop ACC Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a 21 _endasm return cin void putchar char cout ACC cout _asm Icall 0x0030 _endasm MMMM main must be at the bottom of all other files int 1 char cin_char main while cin_char q printf Press a button n putchar 0x0a line feed putchar Ox0d carriage return cin_char getchQ printf The character you entered is printf c cin_char putchar 0x0a line feed putchar Ox0d carriage return printf press any key to continue putchar Ox0a putchar Ox0d 5 15 Experiment 50 Program listing t50_xdata c use of xdata and serial port test50 ver3 12 A more complete testing program including the use of xdata and serial port is the t50_xdat
25. his diagram above shows the two 8255s located at E800 and E000 and have their CSs connected to the E800 and E000 decoder output respectively A0 A1 DO D7 RD WR RESET of the 8255s are all connected to their corresponding pins at the 8031 To the 8031 a parallel interface chip is treated as four external data memory locations and each 825 has 3 sets of 8 bit input output pins For example in 8255 U9 the four addresses E000 E001 E002 E003H are the four registers Reg0 Regl Reg2 Reg3 respectively The address decoding of these four registers is similar that in CPU and memory interfacing The upper address lines are fed into the address decoder to form two chip select signals for addresses EOOXH and E800XH That is when an external data read write instruction accessing addresses EOOXH is executed the CS of 8255 U9 will be selected and so on A summary of the functions of the 8255 registers is listed below We can see that occupies 4 locations It is noted that PORTA of the 8255s are already connected to the LEDS so if PORTA is programmed to be output ports we can use them as display devices 8255 U8 at Oxe800 8255at Oxe000 OxE800 port A connected to LEDS 0xE000 port A connected to LEDS OxE801 port B OxE001 port B OxE802 port C OxE002 port C OxE803 control reg OxE003 control reg Table 5 1 8255 address map Watch dog timer MAX691 See the data sheet max691 pdf An external watch dog timer MAX691 wake
26. in 8031 and the use of various peripheral devices such as the 8255 parallel interface device and the real time clock 5 17 Conclusion 27 Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a 5 18 References 1 Official home of SDCC http sdcc sourceforge net 2 Paulmon2 user manual http www pjrc com tech 805 1 pm2_docs commands html 3 SDCC manual C compiler for 8031 SDCCUdoc ps at http www cse cuhk edu hk khwong ceg3430 ceg3430 htm End of this chapter 28 Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a 29
27. or getting user information and displaying text through the standard input output channel It also teaches students to use line line assembly and the use of some external functions for Paulmon 2 18 Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a 19 What does it do Get a character from the keyboard and display it on the screen through the 8031 SBC By so doing we can send commands to the SBC and gets message from it This function uses the build in functions of Paulmon in particular cout Icall 0x0030 and cin Icall 0x0032 see Paulmon2 user build function at http www pjrc com tech 8051 pm2_docs functions html for details Exercise 1 Why do the putchar and getch functions need to have push ACC and pop ACC inside 2 TIunderstand that the SDCC supports printf but requires that you have a putch function in your program I attempt it in test45 c with some success but found a few bugs as listed in the test45 c program listing Please help me to fix the problem Study reference 1 to find possible solutions 3 Development code for atoi ascii to integer So that one can use the keyboard to enter an integer say 132 then this value goes to an integer variable in your program There are open free source code around give me the programs if you have them 4 Development code for itoa integer to ascii Since the current printf doesn t seem to work on p
28. r 0 1 2 3 4 e register_bank_number can be either 0 1 2 3 A typical interrupt service routine will look like this void timer_isr void interrupt 2 using 1 using interrupt 2 and register bank 1 REE C programming statements Readjustment of interrupt vectors As studied before the interrupt vector ISR addresses are at 0x0003 OxOOOB etc But some system may find it more convenient to have some other ISR starting addresses such as the PAULMON and 8031RL board that we are using This issue will be explained in detail in the next section In light of this requirement the SDCC allows you to readjust the interrupt vector according to the starting address of your program address For example in SDCC use the compile line gt sdcc code loc Ox8000 main return test_isr c will set the interrupt vectors to Interrupt Description Vector Address 0 External 0 0x8003 1 Timer 0 0x800B 2 External 1 0x8013 3 Timer 1 0x801B Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a l 4 Serial 0x8023 See SDCC documentation for details In summary you can use the following template And the compile command line is compile line gt Sdcc code loc 0x8000 main return test_isr c test_isr c containing both the main and the your_isr2 Main setup interrupt do something e g an endless loop ISR responding to an interrupt type 2 gt external intl pin 13 of 8031 IN
29. rinting integers so if you can translate an integer into ascii format one can print this using putchar Procedures No need to make any hardware connection just compile the program download and test Program listing test44 c test44 c ver3 12 1 During compilation there is some error but its still works Students please help me to look into it and fix any bug if exits Study reference 1 to find possible solutions include lt 8051 h gt include lt stdio h gt TUTE char getch char cin _asm push ACC _endasm _asm Icall 0x0032 _endasm cin ACC _asm pop ACC _endasm return cin void putchar char cout ACC cout _asm Icall 0x0030 _endasm Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a 20 MMU main must be at the bottom of all other files int 1 char cin_char main do putchar putchar 0x20 ASCII space cin_char getchQ putchar cin_char putchar Ox0d ASCII carriage return putchar Ox0a ASCII line feed while cin_char q 5 14 Experiment 45 Program listing test45 c sometimes unstable test45 c ver3 12 I found that the bugs are 1 It has some compiler error but still works under normal condition But if you are using interrupt by intO or intl it may not work why 2 n doesn t work you have to put in your program the following lines putchar 0x0a line feed putchar Ox0d carria
30. s up the processor by giving a reset signal to the micro controller if it doesn t received any stop reset instruction from the micro controller That means you have to write explicitly in your program to give a regular pulse about 10ms interval to an input bit of the watchdog timer Otherwise the watchdog timer will reset your SBC What is the use of it Imagine your SBC is a security system that works day and night but has a small program loop that tells the watchdog timer it is working fine by giving it regular pulses For example it is interfered by lighting that the system hangs therefore no regular pulses is produced Therefore the watchdog timer will reset by giving a pulse to the reset input of the 8031 the SBC to tell it to start again so as to escape out of the hanging crisis As a result the SBC resumes to its routine work as before Such is a very common scenario that is used widely in the Industry Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a At this stage our robot are not designed for 24 hour service yet so this watchdog timer is not required Perhaps a future non stop robot that can search for a power source to recharge its battery would find this watch dog timer very handy If the master 8051 does not pull the string regularly the dog MAX691 will press the reset button to wake up the master If you don t give me signals that means you have already hanged then I will wake
31. t data CS WR and RD pins on the 8255 8 bit PortA 8 bit Port B 8 bit PortC Figure 5 3 Interface pins and registers of an 8255 We adopt a method called memory mapped IO to connect the 8255 chips to 8031 The method basically treats the 8255 registers Reg0 1 2 3 as certain locations of data memory and by writing to these particular locations we can instruct the 8255 to function as we wish Data can also be read from three data ports of the 8255 by reading those memory locations But we do need to scarify something for that which are some memory address areas in our shared RAM ROM space The 8031R1 SBC chooses the Data space E000 E003H and E800 E803H for these purposes As you can see from the circuit diagram the arrangement is to have CS for the two 8255s connected to the address decoder of address E000 and E800 also WR and RD are connected to the 8031 just as a RAM To avoid conflict between the 8255 sand RAM2 the chip select signal of RAM2 is now A15 A14 constraining the range inside 8000 DFFFH The pity is we can never use the RAM space between E000 FFFFH Moreover space FOOOH is reserved for the LCD display panel control which shall be discussed later CS of 8255 U9 ICS of 8255 U8 A10 A14 PEEL GAL IPSEN 18GV8 used as RD WR address decoder of 8031 000 B001 E002 E003 E800 E801 E802 E803 Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a T
32. tain interrupts by manipulating the interrupt enable the register IE Register IE 1 enable 0 disable For example in C IE IE 0x85 will enable all external interrupt sources int0 int1 Bit7 BitO EA ES ETI EX1 ETO EXO EA enable all interrupts ES Serial interrupt enable bit ET1 Timer overflow interrupt enable EX1 External interrupt enable ETO Timer overflow interrupt enable Mobile Robot chapter 5 Peripheral devices and programming experiments v 2a EXO External interrupt enable Interrupt priority register IP Interrupt priority can also be adjusted by using the interrupt priority register IP Bit7 BitO PS PT1 PX1 PTO PXO Serial Port Timer1 External 1 Timer0 External 0 1 high priority 0 low priority A low priority ISR can be interrupted by a high priority ISR but not by a low priority ISR A high priority interrupt can not be interrupted If two same priority requests arrive at the same time the internal polling sequence will take effect the polling sequence is IEO gt TFO gt IE1 gt TF1 gt gt T 1 serial High priority lt low priority 5 7 Writing the interrupt service routine in C The SDCC interrupt service routine format SDCC allows interrupt service routines to be coded in C using the format void timer_isr void interrupt isr_type using register_bank_number J isr_type can eithe
Download Pdf Manuals
Related Search