Apparatus 8051 evaluation board 8255 evaluation board Reference H-P. M
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PPI/CC Hong Kong Polytechnic University Department Electronic Information Engineering Experiment 8255 chip Objectives study 8255 chip works. After completing this experiment, should know different operation modes 8255 chip configure chip operate particular operation mode. should also know handshake transfer data interface. Software Text editor, 8051 cross-assembler, 8051 linker 8051 programmer
Apparatus 8051 evaluation board 8255 evaluation board Reference H-P. Messmer, "The indispensable hardware book," Addison-Wesley, 1997 Chapter Section Barry Bery, "The Intel Microprocessors: 8086/8088, 80186/80188, 80286, 80386, 80486, Pentium, Pentium Processor, Pentium Pentium III, Pentium Architecture, Programming, Interfacing", Chapter Section 8255 datasheet AT89S8252 datasheet (instruction set)
Background 8255 chip general purpose programmable device which designed with Intel most other microprocessors. 8255 pins divided into groups pins each. groups denoted port port port respectively. Every ports configured either input port output port. 8255 programmable three different modes: Mode simple unidirectional input/output without handshake Mode unidirectional input/output with handshake some pins port Mode bidirectional input/output with handshake some pins port Handshake common technique used transfer data interface. computer device usually operate different system clock rates hence data transfer between their corresponding interface reliable. example, device might fast enough
CSF-LAB/PPI 8255/CC/EIE PolyU/p.1
catch data transmitted from CPU. Handshake provides means improve reliability data transfer. Method details this lab, will study program 8255 chip operate different operation modes with 8051 evaluation board 8255 evaluation board. Figure shows setup system. requested modify some given 8051 program modules with text editor computer. modified programs, when they 8051 evaluation board, should able program port port 8255 8255 evaluation board operate their operation modes. assemble link your program modules with provided crossassembler linker generate executable files. Executable files then loaded 8051 evaluation board printer port computer program on-board AT89S8252. AT89S8252 low-power, high-performance CMOS 8-bit microcomputer with bytes Downloadable Flash programmable erasable read only memory bytes EEPROM. device manufactured Atmel compatible with industry standard 80C51 instruction pinout.
printer port Computer
8051 evaluation board
8051 local
8255 evaluation board
Figure Setup system After programming AT89S8252, AT89S8252 executes loaded program configure 8255 ports 8255 should operate desired modes. there ports 8255 each them programmed input output port, there number possible configurations. this lab, four configurations given Table will studied. configuration Port Port Port Mode input Mode output Don't care Mode input Mode output Handshake port Mode input Mode output Handshake port Mode input Mode output Handshake ports Table Some configurations 8255
requested following this lab. Setup apparatus shown Figure CSF-LAB/PPI 8255/CC/EIE PolyU/p.2
Appendix lists program configuration (Ai0Bo0.asm). This program repeatedly reads port writes data read port Assemble, link load program into 8051 evaluation board. refer Appendix details. program observe behavior evaluation board. define input with switch connected port LEDs connected port show data input. Study program. special attention procedures configuring 8255 setting value control register. derive your setting from datasheet information provided Appendix Check yours identical provided program.
Device
port Data
8051 (CPU)
Data
8255 (PPI)
port
Data
Device
Appendix lists program (Ai0Bo0X.asm) configuration well. this program, 2.5s delay added into loop. doing simulates case that periodically reads port reports result port immediately. Port programmed blink before reports result. Load program into AT89S8252 evaluation board what happens. Since port operates mode handshake exploited. does know when data comes. Suppose every change switch corresponds data byte transferred from external device. Answer following questions. receive report inputs from device device transfers data rate bytes second? Suppose device transfers data rate byte second. know there available data from device when tries read byte from port stop reading reporting rubbish such case? Appendix lists program configuration 2(Ai1Bo0X.asm). this program, port operates mode handshaking signal provided through port 8255 hence make handshake synchronize itself with external device data transfer. This makes transfer much more reliable.
CSF-LAB/PPI 8255/CC/EIE PolyU/p.3
Data
Device
port
8051 (CPU)
Data
8255 (PPI)
port
Data
Device
Load program into AT89S8252 evaluation board Change setting switch press button marked `port mode input' 8255 evaluation board once. This action corresponds that external device generates strobe signal 8255 when data ready transmission. What happens when this? Repeat steps different speed. Does miss receiving reporting your inputs? Does read something even though anything? Study program carefully. program uses handshake improve performance. Ai1Bo0X.asm does with programmed-I/O technique. keeps checking handshake signal waits until data ready. This keeps busy doing something without contribution. released using interrupt handle data transfer. Appendix lists incomplete program configuration 2(Ai1Bo0.asm). better alternative Ai1Bo0X.asm.
INTR
Data
Device
port
8051 (CPU)
Data
8255 (PPI)
port
Data
Device
Complete program filling blank fields. Test your program with evaluation boards. Study program exploits interrupt job. Appendix lists incomplete program configuration 3(Ai0Bo1.asm). Complete program test your program with evaluation boards. Record your observation.
CSF-LAB/PPI 8255/CC/EIE PolyU/p.4
Device
Data
port
8051 (CPU)
Data
8255 (PPI)
port
Data
INTR
Device
Based Ai1Bo0.asm Ai0Bo1.asm, write program configure 8255 operate configuration Test your program verify functions with evaluation boards.
INTR
Data
Device
port
8051 (CPU)
Data
8255 (PPI)
port
Data
INTR
Device
configure 8255 function other operation modes time allowed. (For more capable student) Appendix Appendix Schematic diagrams evaluation boards Appendix Summary technical information 8255 Appendix Editing, assembling, linking loading programs 8051 evaluation board Appendix Program listing Appendix View evaluation boards
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Appendix Schematic diagrams evaluation boards
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Appendix Summary technical information 8255 Internal structure:
Port register addresses:
Port connections:
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Status word obtained reading port
Command words:
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Operation modes:
Mode operation
Mode operation
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Set/reset IRTEs:
Port Interrupt Signal Number MODE Port Port Port Port MODE Port Port enable Interrupt Request Port
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Appendix Editing, assembling, linking loading programs 8051 evaluation board text editor such Notepad Windows edit your 8051 program. Then assemble link your program make loadable evaluation board debugging. Suppose your program ready stored working directory where 8051 crossassembler(X8051.exe) 8051 linker(Link.exe) X8051.exe activate crossassembler. Figure shows user interface cross-assembler. interface, crossassembler will prompt inputting listing destination, input filename output filename. have specify input filename. others, skip them just entering error detected cross-assembler, object file with extension `.obj' will generated.
Figure User interface X8051.exe Link.exe activate linker. Figure shows user interface linker. linker will prompt inputting parameters. need specify input filename. should object file with extension `.obj'. example, Figure shows case that input file pgm8051.obj. skip other prompts just entering error detected, binary file with extension `.hex' will generated.
Figure User interface Link.exe universal programmer called PonyProg provided this lab. Figure shows user interface provided programmer. This programmer program specified binary file into flash CSF-LAB/PPI 8255/CC/EIE PolyU/p.12
memory 8051-compatiable controller printer port computer system. order successfully, have make sure that device want program AT89S8252. check (and select) listbox interface shown Figure Besides, have check interface setup selecting `Setup' pulldown menu `Options'. Select setting shown Figure
Figure User interface programmer After configuring programmer, load program, namely, file extension `.hex', into working environment program AT89S8252 evaluation board. load program into working environment, push fourth pushbutton from left toolbar then select desired file. Figure shows snapshot user interface after program `pgm8051.hex' loaded into environment. Then push second pushbutton from left toolbar load program into AT89S8252.
CSF-LAB/PPI 8255/CC/EIE PolyU/p.13
Figure Setting interface between evaluation board computer
Figure snapshot user interface after program loaded into working environment
CSF-LAB/PPI 8255/CC/EIE PolyU/p.14
Appendix Program listing listing Ai0Bo0.asm
Ai0Bo0.asm Port mode input Port mode output Input data from port output prot 8000h pa+1 pa+2 pa+3 prot prot prot control register djnz djnz r6,$1 r5,delay
;-end
ajmp main ;-main: sp,#60h call movx loop: movx movx dptr,#pa a,@dptr dptr,#pb @dptr,a loop r5,#10 delay a,#90h dptr,#cr @dptr,a
stack pointer address delay 10ms 8255 initialization port mode input port mode output
input from port output port
;-delay: r6,#50 r7,#100 djnz r7,$2
delay time r5*10ms
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listing Ai0Bo0X.asm
Ai0Bo0X.asm Port mode input Port mode output Input data from port output prot 8000h pa+1 pa+2 pa+3 prot prot prot control register
call movx movx
delay dptr,#pa a,@dptr dptr,#pb @dptr,a loop
input from port output port
ajmp main ;-main: sp,#60h call movx loop: call movx call movx r5,#250 delay a,#0 dptr,#pb @dptr,a r5,#2 delay a,#255 dptr,#pb @dptr,a r5,#2 r5,#10 delay a,#90h dptr,#cr @dptr,a
stack pointer address delay 100ms 8255 initialization port mode input port mode output periodically wait 2.5s, data dump delay 2.5s clear port 20ms port 20ms
;-delay: r6,#50 r7,#100 djnz r7,$2 djnz r6,$1 djnz r5,delay ;-end
delay time r5*10ms
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listing Ai1Bo0X.asm
Ai1Bo0X.asm Port mode input Port mode output Input data from port output prot ajmp 8000h pa+1 pa+2 pa+3 main prot prot prot control register
call movx movx
delay dptr,#pa a,@dptr dptr,#pb @dptr,a loop
input from port output port
;-main: sp,#60h call movx loop: movx movx call movx dptr,#pc a,@dptr a,#20h loop a,#0 dptr,#pb @dptr,a r5,#2 delay a,#255 dptr,#pb @dptr,a r5,#2 r5,#10 delay a,#b0h dptr,#cr @dptr,a
stack pointer address delay 10ms 8255 initialization port mode input port mode output
;-delay: r6,#50 r7,#100 djnz r7,$2 djnz r6,$1 djnz r5,delay ;-end
delay time r5*10ms
status word 8255 check IBF(bit 5)=1
clear port 20ms port 20ms
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listing Ai1Bo0.asm
Ai1Bo0.asm Port mode input Port mode output Input data from port output prot 8000h pa+1 pa+2 pa+3 prot prot prot control register
int1: call movx reti ;-delay: r6,#50 r7,#100 djnz r7,$2 djnz r6,$1 djnz r5,delay ;-end delay time r5*10ms r5,#200 delay dptr,#pa a,@dptr delay 200ms make visible input from port
ajmp main ajmp int1 ;-main: sp,#60h setb setb setb call movx movx loop: movx dptr,#pb @dptr,a loop r5,#10 delay dptr,#cr @dptr,a dptr,#cr @dptr,a
stack pointer address int1 negative edge trigger enable hardware interrupt enable int1 delay 10ms 8255 initialization port mode input port mode output enable interrupt request port
output port
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listing Ai0Bo1.asm
Ai0Bo1.asm Port mode input Port mode output Input data from port output prot 8000h prot pa+1 prot pa+2 prot pa+3 control register ajmp main ajmp int0 ;-main: sp,#60h setb setb setb call movx movx loop: movx dptr,#pa a,@dptr loop input from port r5,#10 delay dptr,#cr @dptr,a dptr,#cr @dptr,a
movx reti
dptr,#pb @dptr,a
output port
;-delay: r6,#50 r7,#100 djnz r7,$2 djnz r6,$1 djnz r5,delay ;-end
delay time r5*10ms
stack pointer address int0 negative edge trigger enable hardware interrupt enable int0 delay 10ms 8255 initialization port mode input port mode output enable interrupt request port
;-int0:
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listing Ai1Bo1.asm
Ai1Bo1.asm Port mode input Port mode output Input data from port output prot 8000h prot pa+1 prot pa+2 prot pa+3 control register ajmp main ajmp int0 ajmp int1 ;-main: sp,#60h setb setb setb setb setb call movx movx movx r5,#10 delay dptr,_ @dptr,a dptr,_ @dptr,a dptr,_ @dptr,a
loop: loop ;-int0: dptr,_ movx @dptr,a reti ;-int1: dptr,_ movx a,@dptr reti ;-delay: r6,#50 r7,#100 djnz r7,$2 djnz r6,$1 djnz r5,delay ;-end delay time r5*10ms
output port
input from port
stack pointer address int0 negative edge trigger int1 negative edge trigger enable hardware interrupt enable int0 enable int1 delay 10ms 8255 initialization port mode input port mode output enable interrupt request port enable interrupt request port
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Appendix Views evaluation boardsProgram listing
Figure A.E-1 8051 evaluation board
Figure A.E-2 8255 evaluation board
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