#include <stdbool.h>
#include <util/delay.h>
#include "debug.h"
+#include "ring_buffer.h"
#include "ibm4704.h"
void ibm4704_init(void)
{
- inhibit();
+ inhibit(); // keep keyboard from sending
+ IBM4704_INT_INIT();
+ IBM4704_INT_ON();
+ idle(); // allow keyboard sending
}
/*
bool parity = true; // odd parity
ibm4704_error = 0;
+ IBM4704_INT_OFF();
+
/* Request to send */
idle();
clock_lo();
/* Data bit */
for (uint8_t i = 0; i < 8; i++) {
WAIT(clock_hi, 100, 0x40+i);
- //_delay_us(5);
if (data&(1<<i)) {
parity = !parity;
data_hi();
/* End */
WAIT(data_lo, 100, 0x36);
- inhibit();
- _delay_us(200); // wait to recover clock to hi
+ idle();
+ IBM4704_INT_ON();
return 0;
ERROR:
- inhibit();
- if (ibm4704_error >= 0x30) {
- xprintf("x%02X ", ibm4704_error);
+ idle();
+ if (ibm4704_error > 0x30) {
+ xprintf("S:%02X ", ibm4704_error);
}
- _delay_us(200); // wait to recover clock to hi
+ IBM4704_INT_ON();
return -1;
}
-/* receive data when host want else inhibit communication */
+/* wait forever to receive data */
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;
+ while (!rbuf_has_data()) {
+ _delay_ms(1);
+ }
+ return rbuf_dequeue();
+}
+
+uint8_t ibm4704_recv(void)
+{
+ if (rbuf_has_data()) {
+ return rbuf_dequeue();
+ } else {
+ return -1;
+ }
}
/*
----------------
Data bits are LSB first and Parity is odd. Clock has around 60us high and 30us low part.
- ____ __ __ __ __ __ __ __ __ __ ________
-Clock \____/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/
+ ____ __ __ __ __ __ __ __ __ __ _______
+Clock \_____/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/
____ ____ ____ ____ ____ ____ ____ ____ ____ ____
Data ____/ X____X____X____X____X____X____X____X____X____X________
Start 0 1 2 3 4 5 6 7 P Stop
Start bit: can be long as 300-350us.
Inhibit: Pull Data line down to inhibit keyboard to send.
-Timing: Host reads bit while Clock is hi.
+Timing: Host reads bit while Clock is hi.(rising edge)
Stop bit: Keyboard pulls down Data line to lo after 9th clock.
*/
-uint8_t ibm4704_recv(void)
+ISR(IBM4704_INT_VECT)
{
- 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, 0x11); // wait for keyboard to send
- WAIT(data_hi, 100, 0x12); // can be delayed that long
+ static enum {
+ BIT0, BIT1, BIT2, BIT3, BIT4, BIT5, BIT6, BIT7, PARITY, STOP
+ } state = BIT0;
+ // LSB first
+ static uint8_t data = 0;
+ // Odd parity
+ static uint8_t parity = false;
- WAIT(clock_hi, 100, 0x13); // 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);
- }
+ ibm4704_error = 0;
- /* parity */
- WAIT(clock_hi, 100, 0x17);
- if (data_in() != parity) {
- ibm4704_error = IBM4704_ERR_PARITY;
- goto ERROR;
+ switch (state) {
+ case BIT0:
+ case BIT1:
+ case BIT2:
+ case BIT3:
+ case BIT4:
+ case BIT5:
+ case BIT6:
+ case BIT7:
+ data >>= 1;
+ if (data_in()) {
+ data |= 0x80;
+ parity = !parity;
+ }
+ break;
+ case PARITY:
+ if (data_in()) {
+ parity = !parity;
+ }
+ if (!parity)
+ goto ERROR;
+ break;
+ case STOP:
+ // Data:Low
+ WAIT(data_lo, 100, state);
+ rbuf_enqueue(data);
+ ibm4704_error = IBM4704_ERR_NONE;
+ goto DONE;
+ break;
+ default:
+ goto ERROR;
}
- WAIT(clock_lo, 150, 0x18);
-
- /* stop bit */
- WAIT(clock_hi, 100, 0x19);
- WAIT(data_lo, 1, 0x19);
-
- inhibit();
- _delay_us(200); // wait to recover clock to hi
- return data;
+ state++;
+ goto RETURN;
ERROR:
- if (ibm4704_error > 0x12) {
- xprintf("x%02X ", ibm4704_error);
- }
- inhibit();
- _delay_us(200); // wait to recover clock to hi
- return -1;
+ ibm4704_error = state;
+ while (ibm4704_send(0xFE)) _delay_ms(1); // resend
+ xprintf("R:%02X%02X\n", state, data);
+DONE:
+ state = BIT0;
+ data = 0;
+ parity = false;
+RETURN:
+ return;
}