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/*
Copyright 2010,2011,2012,2013 Jun WAKO <wakojun@gmail.com>
*/
#include <stdbool.h>
#include <util/delay.h>
#include "debug.h"
#include "ibm4704.h"
#define WAIT(stat, us, err) do { \
if (!wait_##stat(us)) { \
ibm4704_error = err; \
goto ERROR; \
} \
} while (0)
uint8_t ibm4704_error = 0;
void ibm4704_init(void)
{
// POR
//_delay_ms(2500);
//while ( 0xA3 != ibm4704_recv() ) ;
inhibit();
DDRD |= 1<<3;
PORTD &= ~(1<<3);
}
uint8_t ibm4704_send(uint8_t data)
{
bool parity = true; // odd parity
ibm4704_error = 0;
/* Request to send */
idle();
clock_lo();
PIND |= 1<<3;
/* wait for Start bit(Clock:lo/Data:hi) */
WAIT(data_hi, 300, 0x30);
/* Data bit */
for (uint8_t i = 0; i < 8; i++) {
WAIT(clock_hi, 100, 0x31);
//_delay_us(5);
PIND |= 1<<3;
if (data&(1<<i)) {
parity = !parity;
data_hi();
} else {
data_lo();
}
WAIT(clock_lo, 100, 0x32);
}
/* Parity bit */
WAIT(clock_hi, 100, 4);
PIND |= 1<<3;
if (parity) { data_hi(); } else { data_lo(); }
WAIT(clock_lo, 100, 5);
/* Stop bit */
WAIT(clock_hi, 100, 4);
data_hi();
/* End */
WAIT(data_lo, 100, 6);
inhibit();
_delay_us(200); // wait to recover clock to hi
return 0;
ERROR:
inhibit();
xprintf("x%02X ", ibm4704_error);
_delay_us(200); // wait to recover clock to hi
return -1;
}
/* receive data when host want else inhibit communication */
uint8_t ibm4704_recv_response(void)
{
// 250 * 100us(wait start bit in ibm4704_recv)
uint8_t data = 0;
uint8_t try = 250;
do {
data = ibm4704_recv();
} while (try-- && ibm4704_error);
return data;
}
/*
Keyboard to Host:
Clock ~~~~___~~_~~_~~_~~_~~_~~_~~_~~_~~_~~~~~~~~ H:60us/L:30us
Data ____~~X==X==X==X==X==X==X==X==X==X________
| 0 1 2 3 4 5 6 7 P(odd)
| LSB MSB
Start bit(80us)
*/
uint8_t ibm4704_recv(void)
{
uint8_t data = 0;
bool parity = true; // odd parity
ibm4704_error = IBM4704_ERR_NONE;
idle();
_delay_us(5); // wait for line settles
/* start bit */
WAIT(clock_lo, 100, 1); // wait for keyboard to send
WAIT(data_hi, 100, 2); // can be delayed that long
WAIT(clock_hi, 100, 3); // first rising edge which can take longer
/* data */
for (uint8_t i = 0; i < 8; i++) {
WAIT(clock_hi, 100, 0x20+i);
//_delay_us(5);
if (data_in()) {
parity = !parity;
data |= (1<<i);
}
WAIT(clock_lo, 150, 0x28+i);
}
/* parity */
WAIT(clock_hi, 100, 7);
if (data_in() != parity) {
ibm4704_error = IBM4704_ERR_PARITY;
goto ERROR;
}
WAIT(clock_lo, 150, 8);
/* stop bit */
WAIT(clock_hi, 100, 9);
WAIT(data_lo, 1, 9);
inhibit();
_delay_us(200); // wait to recover clock to hi
return data;
ERROR:
if (ibm4704_error > 2) {
xprintf("x%02X ", ibm4704_error);
}
inhibit();
_delay_us(200); // wait to recover clock to hi
return -1;
}
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