/* terminate a transmission if we have */
inhibit();
- _delay_us(100);
+ _delay_us(100); // [4]p.13
- /* start bit [1] */
+ /* 'Request to Send' and Start bit */
data_lo();
clock_hi();
- WAIT(clock_lo, 15000, 1);
- /* data [2-9] */
+ WAIT(clock_lo, 10000, 10); // 10ms [5]p.50
+
+ /* Data bit[2-9] */
for (uint8_t i = 0; i < 8; i++) {
_delay_us(15);
if (data&(1<<i)) {
WAIT(clock_hi, 50, 2);
WAIT(clock_lo, 50, 3);
}
- /* parity [10] */
+
+ /* Parity bit */
_delay_us(15);
if (parity) { data_hi(); } else { data_lo(); }
WAIT(clock_hi, 50, 4);
WAIT(clock_lo, 50, 5);
- /* stop bit [11] */
+
+ /* Stop bit */
_delay_us(15);
data_hi();
- /* ack [12] */
+
+ /* Ack */
WAIT(data_lo, 50, 6);
WAIT(clock_lo, 50, 7);
return 0;
}
-// Do polling data from keyboard to get response to last command.
uint8_t ps2_host_recv_response(void)
{
+ // Command may take 25ms/20ms at most([5]p.46, [3]p.21)
uint8_t retry = 25;
while (retry-- && !pbuf_has_data()) {
- _delay_ms(1); // without this delay it seems to fall into deadlock
+ _delay_ms(1);
}
return pbuf_dequeue();
}
}
SREG = sreg;
}
-
static inline uint8_t pbuf_dequeue(void)
{
uint8_t val = 0;