第 7 章 可编程接口芯片
DESCRIPTION
第 7 章 可编程接口芯片. 可编程接口概术 可编程并行输入／输出接口芯片 8255A 可编程定时／计数器接口芯片 8253. 可编程接口概术 一个简单的具有输入功能和输出功能的可编程接口 电路如下图，它包括一个输入接口，其组成主要是八位的三态门；一个输出接口，其组成主要是八位的锁存器；另外还有八位的多路转换开关及控制这个开关的寄存器 FF 。. 用户对寄存器 FF 写入的内容称为命令字或方式控制字，而寄存器 FF 称为命令寄存器，相应的端口称为命令端口或控制端口，对可编程芯片初始化过程实际上就是对芯片的控制端口写入各种命令字的操作过程。. 目前常用的可编程芯片有如下几种： - PowerPoint PPT PresentationTRANSCRIPT
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7 8255A8253
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FF
-
FF
I/O
8
8
8
8
-
FFFF
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8255A I/O8253 /8251 I/O8259A
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7.1 8255A 8255AIO8086MCS51Z80CPU8255A3CPU
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8255A AB
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8255A
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1 8255A824APA7PA0I/OBPB7PB0I/OCPC7PC0I/OPC7PC0
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2CPU D7D0RESETCPUA0A1
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3 8255AVCCGNDVCC5V GND
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8255A18255A 8255A 0 1 2
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28255A 8255A8255
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1 8255A3ABAB:
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2C10 10
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3 8255A12CCI/O
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1
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8255A 18255A0 18255AAB0AB
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LED
a
g
DP
f
e
d
b
c
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mov al,90h8255mov dx,ctrl_portout dx , almov dx,a_portin al,dx;and al,0fh4mov bx,offset tab1xlatmov dx,b_portout dx,al
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28255A1 AA AA A8255AACPUCPUA
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8255A1
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8255A1 ACPUIBFA
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8255ASTBAIBFA
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28255AAB10A8B81CPUB
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2
8255A
K
K7
K0
PA0
PA7
PC4
PB0
PB7
PC5
LED0
LED7
LED
STBA
IBFA
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1K0K72KA CPU8255A3IBFALED8255A CPUACPU 4CPULED51
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8255I/O88H8EHmov al,10111001bA1loop1 in al,8chCtest al,00100000bIBFAjz loop1mov cx,0ffffhLED3loop2loop loop2in al,80hLED4out 82h,alBjmp loop1
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38255A1 AA A8255AACPUCPUA
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8255A1
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ACPUIBFA
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OBFAACKA OBFA8255AA ACKAA
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38255AA1810,A
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3
8255A
K
PC7
PA0
PA7
PC6
LED0
LED7
LED
+5V
ACKA
OBFA
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1 CPUA2 LEDLED3 4 KACKCPU
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mov cx,1010mov bx,offset xxbxloop1: mov al,[bx]out 88h,alAloop2:in al,8chCanl al,80hIBOAjnz loop2 ,; LED2call delay LED 4inc bx loop loop110
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48255A2 AA A8255AACPUCPUA AAAA
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8255AAB218255ACI/OB0C3I/O
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82551 480868255A0BUFF400HACK
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1D7D02STB3BUSYBUSY
8255A
D0
D7
PC0
PC4
STB
BUSY
PA0
PA7
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print_data proc dlprint1: in al,c_portCtest al, 00010000bbusyjnz print1 busymov al,dl out a_port,alA mov al,00000000b out ctrl_port,almov al,00000001b out ctrl_port,alretprint_datA endp
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2 58
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8255A
A
PA7||PA0
B
8255A
PB7||PB0
+5V
LED6
LED7
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a i0 b i c i d e i1>i f i8b g 8
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a_port equ 80h8255Ab_port equ 82hc_port equ 84hctrl_port equ 86hdatasegmenttab1db 3FH,06H,5BH,4FH,,dispbuffdb 2,0,0,2,0,8,2,2 dataends
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3 6I/O
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8255A
PC0PC1PC2PC3PC4PC5PC6PC7
K8
K10
K9
K11
+5V
K0
K2
K1
K3
K4
K6
K5
K7
K12
K14
K13
K15
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7. 2 8253 INTEL8253825331616553562MHz
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8253
-
8253
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8253 8253825382534/
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825310 0aGATE1bOUT0c0OUT01
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21 1aGATEGATEbOUTc 0OUT
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3 22a GATE1CLKb 1CLK0OUT2CLKc 0
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43 23
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544a GATE1OUTb 0OUTCLKOUT
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4
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65 4OUT4GATE
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5
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8253 8253OUTGATE
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825323OUT23GATE
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0145CPUGATE04CPUGATEGATE15OUT0145
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8253 11MHz82530.50.5825380H86H
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1 82531MHz11Hz1N
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825365536N1000000
2
OUT1
GATE1
CLK1
1KHz
1MHz
82530
OUT0
GATE0
CLK0
82531
5V
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3 113023 02BCD13BCD
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4mov al,00110101b0out 86h,almov al,000out 80h,almov al,10hout 80h,almov al,01110110b1out 86h,al mov al,0e0h103E8H=1000BCDout 82h,almov al,03hout 82h,al
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2 PC100001KHz
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1 01KHz10100000GATE11KHz
OUT1
GATE1
CLK1
1MHz
82530
OUT0
GATE0
CLK0
82531
5V
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2 11KHz 300041GATE0OUTOUT00
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3 N01000
4