143 lines
3 KiB
C
143 lines
3 KiB
C
/*
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Copyright 2010,2011,2012,2013 Jun WAKO <wakojun@gmail.com>
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*/
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#include <stdbool.h>
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#include <util/delay.h>
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#include "debug.h"
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#include "ibm4704.h"
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#define WAIT(stat, us, err) do { \
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if (!wait_##stat(us)) { \
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ibm4704_error = err; \
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goto ERROR; \
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} \
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} while (0)
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uint8_t ibm4704_error = 0;
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void ibm4704_init(void)
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{
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inhibit();
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}
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uint8_t ibm4704_send(uint8_t data)
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{
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bool parity = true; // odd parity
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ibm4704_error = 0;
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/* Request to send */
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idle();
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clock_lo();
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/* wait for Start bit(Clock:lo/Data:hi) */
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WAIT(data_hi, 300, 0x30);
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/* Data bit */
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for (uint8_t i = 0; i < 8; i++) {
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WAIT(clock_hi, 100, 0x40+i);
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//_delay_us(5);
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if (data&(1<<i)) {
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parity = !parity;
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data_hi();
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} else {
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data_lo();
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}
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WAIT(clock_lo, 100, 0x48+i);
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}
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/* Parity bit */
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WAIT(clock_hi, 100, 0x34);
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if (parity) { data_hi(); } else { data_lo(); }
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WAIT(clock_lo, 100, 0x35);
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/* Stop bit */
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WAIT(clock_hi, 100, 0x34);
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data_hi();
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/* End */
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WAIT(data_lo, 100, 0x36);
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inhibit();
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_delay_us(200); // wait to recover clock to hi
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return 0;
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ERROR:
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inhibit();
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if (ibm4704_error >= 0x30) {
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xprintf("x%02X ", ibm4704_error);
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}
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_delay_us(200); // wait to recover clock to hi
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return -1;
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}
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/* receive data when host want else inhibit communication */
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uint8_t ibm4704_recv_response(void)
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{
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// 250 * 100us(wait start bit in ibm4704_recv)
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uint8_t data = 0;
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uint8_t try = 250;
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do {
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data = ibm4704_recv();
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} while (try-- && ibm4704_error);
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return data;
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}
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/*
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Keyboard to Host:
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Clock ~~~~___~~_~~_~~_~~_~~_~~_~~_~~_~~_~~~~~~~~ H:60us/L:30us
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Data ____~~X==X==X==X==X==X==X==X==X==X________
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| 0 1 2 3 4 5 6 7 P(odd)
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| LSB MSB
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Start bit(80us)
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*/
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uint8_t ibm4704_recv(void)
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{
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uint8_t data = 0;
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bool parity = true; // odd parity
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ibm4704_error = IBM4704_ERR_NONE;
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idle();
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_delay_us(5); // wait for line settles
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/* start bit */
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WAIT(clock_lo, 100, 0x11); // wait for keyboard to send
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WAIT(data_hi, 100, 0x12); // can be delayed that long
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WAIT(clock_hi, 100, 0x13); // first rising edge which can take longer
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/* data */
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for (uint8_t i = 0; i < 8; i++) {
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WAIT(clock_hi, 100, 0x20+i);
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//_delay_us(5);
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if (data_in()) {
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parity = !parity;
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data |= (1<<i);
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}
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WAIT(clock_lo, 150, 0x28+i);
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}
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/* parity */
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WAIT(clock_hi, 100, 0x17);
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if (data_in() != parity) {
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ibm4704_error = IBM4704_ERR_PARITY;
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goto ERROR;
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}
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WAIT(clock_lo, 150, 0x18);
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/* stop bit */
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WAIT(clock_hi, 100, 0x19);
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WAIT(data_lo, 1, 0x19);
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inhibit();
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_delay_us(200); // wait to recover clock to hi
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return data;
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ERROR:
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if (ibm4704_error > 0x12) {
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xprintf("x%02X ", ibm4704_error);
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}
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inhibit();
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_delay_us(200); // wait to recover clock to hi
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return -1;
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}
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