// Used by the master to synchronize timing with the slave.
static
void sync_recv(void) {
serial_input();
// This shouldn't hang if the slave disconnects because the
// serial line will float to high if the slave does disconnect.
while (!serial_read_pin());
serial_delay();
}
void abc99_device::txd_w(int state)
{
if (m_si != state)
{
m_si = state;
serial_input();
}
}
void serial_slave_init(void) {
serial_input();
// Enable INT0
EIMSK |= _BV(INT0);
// Trigger on falling edge of INT0
EICRA &= ~(_BV(ISC00) | _BV(ISC01));
}
// Copies the serial_slave_buffer to the master and sends the
// serial_master_buffer to the slave.
//
// Returns:
// 0 => no error
// 1 => slave did not respond
int serial_update_buffers(void) {
// this code is very time dependent, so we need to disable interrupts
cli();
// signal to the slave that we want to start a transaction
serial_output();
serial_low();
_delay_us(1);
// wait for the slaves response
serial_input();
serial_high();
_delay_us(SERIAL_DELAY);
// check if the slave is present
if (serial_read_pin()) {
// slave failed to pull the line low, assume not present
sei();
return 1;
}
// if the slave is present syncronize with it
sync_recv();
uint8_t checksum_computed = 0;
// receive data from the slave
for (int i = 0; i < SERIAL_SLAVE_BUFFER_LENGTH; ++i) {
serial_slave_buffer[i] = serial_read_byte();
sync_recv();
checksum_computed += serial_slave_buffer[i];
}
uint8_t checksum_received = serial_read_byte();
sync_recv();
if (checksum_computed != checksum_received) {
sei();
return 1;
}
uint8_t checksum = 0;
// send data to the slave
for (int i = 0; i < SERIAL_MASTER_BUFFER_LENGTH; ++i) {
serial_write_byte(serial_master_buffer[i]);
sync_recv();
checksum += serial_master_buffer[i];
}
serial_write_byte(checksum);
sync_recv();
// always, release the line when not in use
serial_output();
serial_high();
sei();
return 0;
}
/*---------------------------------------------------------------------------*/
void
slip_handle_fd(fd_set *rset, fd_set *wset)
{
if(FD_ISSET(slipfd, rset)) {
serial_input(inslip);
}
if(FD_ISSET(slipfd, wset)) {
slip_flushbuf(slipfd);
}
}
// Reads a byte from the serial line
static
uint8_t serial_read_byte(void) {
uint8_t byte = 0;
serial_input();
for ( uint8_t i = 0; i < 8; ++i) {
byte = (byte << 1) | serial_read_pin();
serial_delay();
_delay_us(1);
}
return byte;
}
void serial_slave_init(void) {
serial_input();
#ifndef USE_SERIAL_PD2
// Enable INT0
EIMSK |= _BV(INT0);
// Trigger on falling edge of INT0
EICRA &= ~(_BV(ISC00) | _BV(ISC01));
#else
// Enable INT2
EIMSK |= _BV(INT2);
// Trigger on falling edge of INT2
EICRA &= ~(_BV(ISC20) | _BV(ISC21));
#endif
}
