Add SX127x TX and RX operation using interrupt

Author: chandrawi

src/SX127x.cpp

@@ -6,12 +6,14 @@ uint32_t SX127x::_spiFrequency = SX127X_SPI_FREQUENCY;
 
 int8_t SX127x::_nssStatic = SX127X_PIN_NSS;
 
-uint8_t SX127x::_statusIrq = 0x00;
+uint8_t SX127x::_statusIrq = 0xFF;
 
 uint32_t SX127x::_transmitTime = 0;
 
 uint8_t SX127x::_payloadTxRx = 0;
 
+int8_t SX127x::_irqStatic = -1;
+
 int8_t SX127x::_pinToLow = -1;
 
 SX127x::SX127x()
@@ -109,6 +111,7 @@ void SX127x::setPins(int8_t nss, int8_t reset, int8_t irq, int8_t txen, int8_t r
  _irq = irq;
  _txen = txen;
  _rxen = rxen;
+ _irqStatic = digitalPinToInterrupt(_irq);
 }
 
 void SX127x::setCurrentProtection(uint8_t current)
@@ -319,7 +322,7 @@ void SX127x::beginPacket()
  }
 }
 
-void SX127x::endPacket()
+void SX127x::endPacket(bool intFlag)
 {
  // set packet payload length
  writeRegister(SX127X_REG_PAYLOAD_LENGTH, _payloadTxRx);
@@ -332,6 +335,11 @@ void SX127x::endPacket()
  writeRegister(SX127X_REG_OP_MODE, _modem | SX127X_MODE_TX);
  _transmitTime = millis();
 
+ // set TX done interrupt on DIO0 and attach TX interrupt handler
+ if (_irq != -1 && intFlag) {
+ writeRegister(SX127X_REG_DIO_MAPPING_1, SX127X_DIO0_TX_DONE);
+ attachInterrupt(_irqStatic, SX127x::_interruptTx, RISING);
+ }
 }
 
 void SX127x::write(uint8_t data)
@@ -357,7 +365,7 @@ void SX127x::write(char* data, uint8_t length)
  write(data_, length);
 }
 
-void SX127x::request(uint32_t timeout)
+void SX127x::request(uint32_t timeout, bool intFlag)
 {
  // clear IRQ flag from last TX or RX operation
  writeRegister(SX127X_REG_IRQ_FLAGS, 0xFF);
@@ -388,6 +396,16 @@ void SX127x::request(uint32_t timeout)
 
  // set device to receive mode
  writeRegister(SX127X_REG_OP_MODE, _modem | rxMode);
+
+ // set RX done interrupt on DIO0 and attach RX interrupt handler
+ if (_irq != -1 && intFlag) {
+ writeRegister(SX127X_REG_DIO_MAPPING_1, SX127X_DIO0_RX_DONE);
+ if (timeout == SX127X_RX_CONTINUOUS) {
+ attachInterrupt(_irqStatic, SX127x::_interruptRxContinuous, RISING);
+ } else {
+ attachInterrupt(_irqStatic, SX127x::_interruptRx, RISING);
+ }
+ }
 }
 
 uint8_t SX127x::available()
@@ -439,20 +457,30 @@ bool SX127x::wait(uint32_t timeout)
  // immediately return when currently not waiting transmit or receive process
  if (_statusIrq) return false;
 
+#ifdef SPI_HAS_NOTUSINGINTERRUPT
+ _spi->usingInterrupt(_irqStatic);
+#endif
  // wait transmit or receive process finish by checking IRQ status
  uint8_t irqFlag = 0x00;
  uint8_t irqFlagMask = _statusWait == SX127X_STATUS_TX_WAIT 
  ? SX127X_IRQ_TX_DONE 
  : SX127X_IRQ_RX_DONE | SX127X_IRQ_RX_TIMEOUT | SX127X_IRQ_CRC_ERR
  ;
  uint32_t t = millis();
- while (!(irqFlag & irqFlagMask)) {
+ while (!(irqFlag & irqFlagMask) && _statusIrq == 0x00) {
  irqFlag = readRegister(SX127X_REG_IRQ_FLAGS);
  // return when timeout reached
  if (millis() - t > timeout && timeout != 0) return false;
  }
+#ifdef SPI_HAS_NOTUSINGINTERRUPT
+ _spi->notUsingInterrupt(_irqStatic);
+#endif
+
+ if (_statusIrq) {
+ // immediately return when interrupt signal hit
+ return false;
 
- if (_statusWait == SX127X_STATUS_TX_WAIT) {
+ } else if (_statusWait == SX127X_STATUS_TX_WAIT) {
  // calculate transmit time and set back txen pin to low
  _transmitTime = millis() - _transmitTime;
  if (_txen != -1) digitalWrite(_txen, LOW);
@@ -489,7 +517,6 @@ uint8_t SX127x::status()
 
  // get status for transmit and receive operation based on status IRQ
  if (statusIrq & SX127X_IRQ_RX_TIMEOUT) return SX127X_STATUS_RX_TIMEOUT;
- else if (!(statusIrq & SX127X_IRQ_HEADER_VALID)) return SX127X_STATUS_HEADER_ERR;
  else if (statusIrq & SX127X_IRQ_CRC_ERR) return SX127X_STATUS_CRC_ERR;
  else if (statusIrq & SX127X_IRQ_TX_DONE) return SX127X_STATUS_TX_DONE;
  else if (statusIrq & SX127X_IRQ_RX_DONE) return SX127X_STATUS_RX_DONE;
@@ -535,6 +562,53 @@ float SX127x::snr()
  return readRegister(SX127X_REG_PKT_SNR_VALUE) / 4.0;
 }
 
+void SX127x::_interruptTx()
+{
+ // calculate transmit time
+ _transmitTime = millis() - _transmitTime;
+
+ // store IRQ status as TX done
+ _statusIrq = SX127X_IRQ_TX_DONE;
+
+ // set back txen pin to low and detach interrupt
+ if (_pinToLow != -1) digitalWrite(_pinToLow, LOW);
+ detachInterrupt(_irqStatic);
+}
+
+void SX127x::_interruptRx()
+{
+ // store IRQ status
+ _statusIrq = readRegister(SX127X_REG_IRQ_FLAGS);
+ // set IRQ status to RX done when interrupt occured before register updated
+ if (!(_statusIrq & 0xF0)) _statusIrq = SX127X_IRQ_RX_DONE;
+
+ // terminate receive mode by setting mode to standby
+ writeBits(SX127X_REG_OP_MODE, SX127X_MODE_STDBY, 0, 3);
+
+ // set back rxen pin to low and detach interrupt
+ if (_pinToLow != -1) digitalWrite(_pinToLow, LOW);
+ detachInterrupt(_irqStatic);
+
+ // set pointer to RX buffer base address and get packet payload length
+ writeRegister(SX127X_REG_FIFO_ADDR_PTR, readRegister(SX127X_REG_FIFO_RX_CURRENT_ADDR));
+ _payloadTxRx = readRegister(SX127X_REG_RX_NB_BYTES);
+}
+
+void SX127x::_interruptRxContinuous()
+{
+ // store IRQ status
+ _statusIrq = readRegister(SX127X_REG_IRQ_FLAGS);
+ // set IRQ status to RX done when interrupt occured before register updated
+ if (!(_statusIrq & 0xF0)) _statusIrq = SX127X_IRQ_RX_DONE;
+
+ // clear IRQ flag from last TX or RX operation
+ writeRegister(SX127X_REG_IRQ_FLAGS, 0xFF);
+
+ // set pointer to RX buffer base address and get packet payload length
+ writeRegister(SX127X_REG_FIFO_ADDR_PTR, readRegister(SX127X_REG_FIFO_RX_CURRENT_ADDR));
+ _payloadTxRx = readRegister(SX127X_REG_RX_NB_BYTES);
+}
+
 void SX127x::writeBits(uint8_t address, uint8_t data, uint8_t position, uint8_t length)
 {
  uint8_t read = _transfer(address & 0x7F, 0x00);

src/SX127x.h

@@ -78,6 +78,11 @@
 #define SX127x_OSC_CRYSTAL 0x00 // crystal oscillator with external crystal
 #define SX127X_OSC_TCXO 0x10 // external clipped sine TCXO AC-connected to XTA pin
 
+// DIO mapping
+#define SX127X_DIO0_RX_DONE 0x00 // set DIO0 interrupt for: RX done
+#define SX127X_DIO0_TX_DONE 0x40 // TX done
+#define SX127X_DIO0_CAD_DONE 0x80 // CAD done
+
 // IRQ flags
 #define SX127X_IRQ_CAD_DETECTED 0x01 // Valid Lora signal detected during CAD operation
 #define SX127X_IRQ_FHSS_CHANGE 0x02 // FHSS change channel interrupt
@@ -108,9 +113,6 @@
 #define SX127X_STATUS_CAD_WAIT LORA_STATUS_CAD_WAIT
 #define SX127X_STATUS_CAD_DETECTED LORA_STATUS_CAD_DETECTED
 #define SX127X_STATUS_CAD_DONE LORA_STATUS_CAD_DONE
-#define SX126X_STATUS_INT_WAIT LORA_STATUS_INT_WAIT
-#define SX126X_STATUS_INT_TX LORA_STATUS_INT_TX
-#define SX126X_STATUS_INT_RX LORA_STATUS_INT_RX
 
 // Default Hardware Configuration
 #define SX127X_PIN_NSS 10
@@ -164,7 +166,7 @@ class SX127x : public BaseLoRa
 
  // Transmit related methods
  void beginPacket();
- void endPacket();
+ void endPacket(bool intFlag=true);
  void write(uint8_t data);
  void write(uint8_t* data, uint8_t length);
  void write(char* data, uint8_t length);
@@ -181,7 +183,7 @@ class SX127x : public BaseLoRa
  }
 
  // Receive related methods
- void request(uint32_t timeout=SX127X_RX_SINGLE);
+ void request(uint32_t timeout=SX127X_RX_SINGLE, bool intFlag=true);
  uint8_t available();
  uint8_t read();
  uint8_t read(uint8_t* data, uint8_t length);
@@ -237,6 +239,9 @@ class SX127x : public BaseLoRa
  static int8_t _irqStatic;
  static int8_t _pinToLow;
 
+ static void _interruptTx();
+ static void _interruptRx();
+ static void _interruptRxContinuous();
  static uint8_t _transfer(uint8_t address, uint8_t data);
 
 };