Jacques Pelletier
This program implements a slave SPI in software for testing the SPI interface of protocoltool.
Fork of
8255_emulator
by 
Jacques Pelletier
Diff: main.cpp
- Revision:
- 1:51bc46468482
- Parent:
- 0:a5957f25b150
- Child:
- 2:0cc974f03339
--- a/main.cpp Fri Jul 26 04:51:00 2013 +0000
+++ b/main.cpp Sun Oct 27 04:32:14 2013 +0000
@@ -5,6 +5,7 @@
#include <stdlib.h>
#include <string.h>
+/*
#define PAR_NEGOTIATE_EXTENSIBILITY_LINK 0x80
#define PAR_NEGOTIATE_REQ_EPP_MODE 0x40
#define PAR_NEGOTIATE_REQ_ECP_MODE 0x10
@@ -15,36 +16,41 @@
#define PAR_NEGOTIATE_REQ_DEV_ID_ECP_RLE_MODE 0x34
#define PAR_NEGOTIATE_NIBBLE_MODE 0x00
#define PAR_NEGOTIATE_BYTE_MODE 0x01
+*/
/*
Instructions for use: connect the mbed to a parallel port using these connexions.
-use a terminal program to connect via USB to the mbed side.
+use a terminal program to connect via USB to the mbed side. */
-This program uses CR to rewrite over the status previously printed. Setup the terminal
-program so that CR = CR without line feed.
+#define PAR_INVERT_OBF_SIGNAL
+
+#define PAR_8255_SEND_MASK 0x80
+#define PAR_8255_RECV_MASK 0x40
-15 nError -> p9
-13 Select -> p10
-12 PE -> p11
-11 Busy -> p12
-10 nAck -> p13
+/*
+ 8255 Parallel Pin Bit
+ PC7 /OBF -> /ACK 10 6
+ PC6 /ACK <- /SLCTIN 17 3
+ PC5 IBF -> BUSY 11 7
+ PC4 /STB <- /STB 1 0
- 1 nStrobe -> p14
-14 nAutoFeed -> p15
-16 nInit -> p16
-17 nSelectIn -> p17
+15 nError -> p9 not used
+13 Select -> p10 not used
+12 PE -> p11 not used
+11 Busy -> p12 IBF
+10 nAck -> p13 /OBF
+
+ 1 nStrobe -> p14 /STB
+14 nAutoFeed -> p15 not used
+16 nInit -> p16 not used
+17 nSelectIn -> p17 /ACK
*/
-DigitalOut nError(p9);
-DigitalOut Select(p10);
-DigitalOut PaperOut(p11);
-DigitalOut Busy(p12);
-DigitalOut nAck(p13);
+DigitalOut IBF(p12); // IBF
+DigitalOut nOBF(p13); // /OBF
-DigitalIn nStrobe(p14);
-DigitalIn nAutoFeed(p15);
-DigitalIn nInit(p16);
-DigitalIn nSelectIn(p17);
+InterruptIn nSTB(p14);
+InterruptIn nACK(p17);
/*
D0 p30 p0.4
@@ -65,98 +71,70 @@
Serial pc(USBTX, USBRX); // tx, rx
-int main() {
+unsigned char rx_data;
+
+// Peripheral should check that there is no output pending from the 8255 to the peripheral before writing to the 8255
+
+// When /STB is falling
+void perif2mbed(void)
+{
+ // read byte from peripheral
+ rx_data = PtrData;
+ IBF = 1;
+}
+
+// When /ACK is rising
+void mbed2perif(void)
+{
+ nOBF = 1;
+ PtrData.input();
+}
+
+void write_byte(unsigned char out)
+{
+ // wait for /OBF = 1 and no read cycle in progress for politeness
+ while ((nOBF == 0) || (IBF == 1));
-char key;
-bool PortIsInput = false;
+ PtrData = out;
+ PtrData.output();
+ nOBF = 0;
+}
+
+unsigned char read_byte(void)
+{
+ while (IBF == 0);
+ IBF = 0;
+ return rx_data;
+}
+
+int main()
+{
+ PtrData.input();
+
+ /* 9600 baud serial port */
+ pc.printf("8255 emulator on mbed\r\n\n");
+
+ IBF = 0;
+ nOBF = 1;
+ nSTB.fall(&perif2mbed);
+ nACK.rise(&mbed2perif);
PtrData.input();
- pc.printf("Parallel port tester on mbed\r\n\n");
- pc.printf("Press keys 0-7,G,H,J,K and L to toggle output bits (inputs on PC)\r\n");
- pc.printf("Press keys I and O to toggle data direction for bits 0-7\r\n");
- pc.printf(" (be sure your PC and mbed don't output at the same time)\r\n\n");
- pc.printf("PINS 9-2 1 14 16 17 ------ 15 13 12 11 10\r\n");
- pc.printf("DATA 7-0 /STB /AF /INIT /SEL_IN ------/ERR SEL PO BUSY /ACK\r\n");
- pc.printf("Keys ------ G H J K L\r\n");
- // XX B B B B ------ B B B B B
- while(1) {
- pc.printf(" %02X %c %c %c %c %c %c %c %c %c \r",
- PtrData & 0xff,
- '0'| nStrobe,
- '0'| nAutoFeed,
- '0'| nInit,
- '0'| nSelectIn,
- '0'| nError,
- '0'| Select,
- '0'| PaperOut,
- '0'| Busy,
- '0'| nAck
- );
-
- if (pc.readable())
+ while(1)
+ {
+ // bytes from peripherals to 8255
+ if (IBF == 1)
{
- key = pc.getc();
- switch(key)
+ IBF = 0;
+ pc.putc(rx_data);
+ }
+ else
+ {
+ if (pc.readable())
{
- case 'I':
- PtrData.input();
- PortIsInput = true;
- break;
- case 'O':
- PtrData.output();
- PortIsInput = false;
- break;
- case '0':
- if (!PortIsInput)
- PtrData = PtrData ^ 0x01;
- break;
- case '1':
- if (!PortIsInput)
- PtrData = PtrData ^ 0x02;
- break;
- case '2':
- if (!PortIsInput)
- PtrData = PtrData ^ 0x04;
- break;
- case '3':
- if (!PortIsInput)
- PtrData = PtrData ^ 0x08;
- break;
- case '4':
- if (!PortIsInput)
- PtrData = PtrData ^ 0x10;
- break;
- case '5':
- if (!PortIsInput)
- PtrData = PtrData ^ 0x20;
- break;
- case '6':
- if (!PortIsInput)
- PtrData = PtrData ^ 0x40;
- break;
- case '7':
- if (!PortIsInput)
- PtrData = PtrData ^ 0x80;
- break;
- case 'G':
- nError = !nError;
- break;
- case 'H':
- Select = !Select;
- break;
- case 'J':
- PaperOut = !PaperOut;
- break;
- case 'K':
- Busy = !Busy;
- break;
- case 'L':
- nAck = !nAck;
- break;
- default:
- ;
+ write_byte(pc.getc());
}
- }
+ }
}
}