unio_value_t _unio_read() {
/* release the bus */
PAOUT |= UNIO_PIN;
/* try to read in middle of low or high period */
delay_micros(unio_half_bitdelay);
if (PAIN & UNIO_PIN) {
/* high */
delay_micros(unio_bitdelay);
if (!(PAIN & UNIO_PIN)) {
/* low */
delay_micros(unio_half_bitdelay);
return UNIO_ZERO;
}
} else {
/* low */
delay_micros(unio_bitdelay);
if (PAIN & UNIO_PIN) {
/* high */
delay_micros(unio_half_bitdelay);
return UNIO_ONE;
}
}
return UNIO_NONE;
}
void _unio_write_1() {
/* low-to-high */
PAOUT &= ~UNIO_PIN;
delay_micros(unio_bitdelay);
PAOUT |= UNIO_PIN;
delay_micros(unio_bitdelay);
}
void _unio_write_0() {
/* high-to-low */
PAOUT |= UNIO_PIN;
delay_micros(unio_bitdelay);
PAOUT &= ~UNIO_PIN;
delay_micros(unio_bitdelay);
}
void unio_header() {
/* drive bus low for at least 5 us */
PAOUT &= ~UNIO_PIN;
delay_micros(/* 18.432 * 5 us = */ 92);
unio_transmit(0x55, 1);
}
void delay_micros (uint n)
{
const uint function_overhead = 6;
while (n > 1000) // To avoid timer overflow
{
delay_micros (1000);
n -= 1000;
}
if (n > function_overhead)
{
TMR1 = 0; // Reset timer to 0
PR1
= (n - function_overhead)
* (PBCLK_FREQUENCY / 1000)
/ 1000;
IFS0bits.T1IF = 0; // Clear overflow flag
T1CONbits.ON = 1; // Turn timer on
while (! IFS0bits.T1IF) // Wait until overflow flag is set
;
}
}
void unio_standby() {
/* drive bus high for at least 600 us */
PAOUT |= UNIO_PIN;
delay_micros(/* 18.432 * 600 us = */ 11059);
}
void delay_millis (uint n)
{
while (n --)
delay_micros (1000);
}
