190 lines
4.6 KiB
190 lines
4.6 KiB
/*
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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 "ring_buffer.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(); // keep keyboard from sending
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IBM4704_INT_INIT();
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IBM4704_INT_ON();
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idle(); // allow keyboard sending
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}
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/*
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Host to Keyboard
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----------------
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Data bits are LSB first and Parity is odd. Clock has around 60us high and 30us low part.
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____ __ __ __ __ __ __ __ __ __ ________
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Clock \______/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/
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^ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ___
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Data ____|__/ X____X____X____X____X____X____X____X____X____X \___
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| Start 0 1 2 3 4 5 6 7 P Stop
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Request by host
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Start bit: can be long as 300-350us.
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Request: Host pulls Clock line down to request to send a command.
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Timing: After Request keyboard pull up Data and down Clock line to low for start bit.
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After request host release Clock line once Data line becomes hi.
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Host writes a bit while Clock is hi and Keyboard reads while low.
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Stop bit: Host releases or pulls up Data line to hi after 9th clock and waits for keyboard pull down the line to lo.
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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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IBM4704_INT_OFF();
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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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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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idle();
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IBM4704_INT_ON();
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return 0;
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ERROR:
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idle();
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if (ibm4704_error > 0x30) {
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xprintf("S:%02X ", ibm4704_error);
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}
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IBM4704_INT_ON();
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return -1;
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}
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/* wait forever to receive data */
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uint8_t ibm4704_recv_response(void)
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{
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while (!rbuf_has_data()) {
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_delay_ms(1);
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}
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return rbuf_dequeue();
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}
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uint8_t ibm4704_recv(void)
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{
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if (rbuf_has_data()) {
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return rbuf_dequeue();
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} else {
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return -1;
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}
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}
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/*
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Keyboard to Host
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----------------
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Data bits are LSB first and Parity is odd. Clock has around 60us high and 30us low part.
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____ __ __ __ __ __ __ __ __ __ _______
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Clock \_____/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/
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____ ____ ____ ____ ____ ____ ____ ____ ____ ____
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Data ____/ X____X____X____X____X____X____X____X____X____X________
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Start 0 1 2 3 4 5 6 7 P Stop
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Start bit: can be long as 300-350us.
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Inhibit: Pull Data line down to inhibit keyboard to send.
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Timing: Host reads bit while Clock is hi.(rising edge)
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Stop bit: Keyboard pulls down Data line to lo after 9th clock.
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*/
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ISR(IBM4704_INT_VECT)
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{
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static enum {
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BIT0, BIT1, BIT2, BIT3, BIT4, BIT5, BIT6, BIT7, PARITY, STOP
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} state = BIT0;
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// LSB first
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static uint8_t data = 0;
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// Odd parity
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static uint8_t parity = false;
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ibm4704_error = 0;
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switch (state) {
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case BIT0:
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case BIT1:
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case BIT2:
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case BIT3:
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case BIT4:
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case BIT5:
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case BIT6:
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case BIT7:
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data >>= 1;
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if (data_in()) {
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data |= 0x80;
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parity = !parity;
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}
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break;
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case PARITY:
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if (data_in()) {
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parity = !parity;
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}
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if (!parity)
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goto ERROR;
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break;
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case STOP:
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// Data:Low
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WAIT(data_lo, 100, state);
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rbuf_enqueue(data);
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ibm4704_error = IBM4704_ERR_NONE;
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goto DONE;
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break;
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default:
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goto ERROR;
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}
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state++;
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goto RETURN;
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ERROR:
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ibm4704_error = state;
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while (ibm4704_send(0xFE)) _delay_ms(1); // resend
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xprintf("R:%02X%02X\n", state, data);
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DONE:
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state = BIT0;
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data = 0;
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parity = false;
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RETURN:
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return;
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}
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