/// @details
/// This call provides direct access to the RFM12B registers. If you're careful
/// to avoid configuring the wireless module in a way which stops the driver
/// from functioning, this can be used to adjust frequencies, power levels,
/// RSSI threshold, etc. See the RFM12B wireless module documentation.
///
/// This call will briefly disable interrupts to avoid clashes on the SPI bus.
///
/// Returns the 16-bit value returned by SPI. Probably only useful with a
/// "0x0000" status poll command.
/// @param cmd RF12 command, topmost bits determines which register is affected.
uint16_t rf12_control(uint16_t cmd) {
#ifdef EIMSK
#if PINCHG_IRQ
#if RFM_IRQ < 8
bitClear(PCICR, PCIE0);
#elif RFM_IRQ < 16
bitClear(PCICR, PCIE1);
#else
bitClear(PCICR, PCIE2);
#endif
#else
bitClear(EIMSK, INT0);
#endif
uint16_t r = rf12_xferSlow(cmd);
#if PINCHG_IRQ
#if RFM_IRQ < 8
bitSet(PCICR, PCIE0);
#elif RFM_IRQ < 16
bitSet(PCICR, PCIE1);
#else
bitSet(PCICR, PCIE2);
#endif
#else
bitSet(EIMSK, INT0);
#endif
#else
// ATtiny
bitClear(GIMSK, INT0);
uint16_t r = rf12_xferSlow(cmd);
bitSet(GIMSK, INT0);
#endif
return r;
}
/// @details
/// This call provides direct access to the RFM12B registers. If you're careful
/// to avoid configuring the wireless module in a way which stops the driver
/// from functioning, this can be used to adjust frequencies, power levels,
/// RSSI threshold, etc. See the RFM12B wireless module documentation.
///
/// This call will briefly disable interrupts to avoid clashes on the SPI bus.
///
/// Returns the 16-bit value returned by SPI. Probably only useful with a
/// "0x0000" status poll command.
/// @param cmd RF12 command, topmost bits determines which register is affected.
uint16_t rf12_control(uint16_t cmd) {
#ifdef EIMSK
bitClear(EIMSK, INT0);
uint16_t r = rf12_xferSlow(cmd);
bitSet(EIMSK, INT0);
#else
// ATtiny
bitClear(GIMSK, INT0);
uint16_t r = rf12_xferSlow(cmd);
bitSet(GIMSK, INT0);
#endif
return r;
}
static void rf12_interrupt () {
// a transfer of 2x 16 bits @ 2 MHz over SPI takes 2x 8 us inside this ISR
// correction: now takes 2 + 8 µs, since sending can be done at 8 MHz
rf12_xfer(0x0000);
if (rxstate == TXRECV) {
uint8_t in = rf12_xferSlow(RF_RX_FIFO_READ);
if (rxfill == 0 && group != 0)
rf12_buf[rxfill++] = group;
rf12_buf[rxfill++] = in;
rf12_crc = _crc16_update(rf12_crc, in);
if (rxfill >= rf12_len + 5 || rxfill >= RF_MAX)
rf12_xfer(RF_IDLE_MODE);
} else {
uint8_t out;
if (rxstate < 0) {
uint8_t pos = 3 + rf12_len + rxstate++;
out = rf12_buf[pos];
rf12_crc = _crc16_update(rf12_crc, out);
} else
switch (rxstate++) {
case TXSYN1:
out = 0x2D;
break;
case TXSYN2:
out = group;
rxstate = - (2 + rf12_len);
break;
case TXCRC1:
out = rf12_crc;
break;
case TXCRC2:
out = rf12_crc >> 8;
break;
case TXDONE:
rf12_xfer(RF_IDLE_MODE); // fall through
default:
out = 0xAA;
}
rf12_xfer(RF_TXREG_WRITE + out);
}
}
