rename spreadfactor and cleanup type change in sx127x

lora.go

@@ -22,9 +22,9 @@ type Config struct {
 	// Must be set when working with implicit headers.
 	MaxImplicitPayloadLength uint8
 	CodingRate               CodingRate
-	SpreadFactor             SpreadFactor // this should probably be called "SpreadingFactor" to be consistent with LoRa terminology
+	SpreadingFactor          SpreadingFactor
-	SyncWord                 uint16       // for new chips sync word is full 16 bits
+	SyncWord                 uint16 // for new chips sync word is full 16 bits
-	TxPower                  int8         // Tx Power in dBm.
+	TxPower                  int8   // Tx Power in dBm.
 	CRC                      bool
 	// Low data rate optimisation flag. The use of this flag is mandated when
 	// the symbol duration exceeds 16ms. Increases reliability at high spreading factors.
@@ -34,9 +34,9 @@ type Config struct {
 }
 
 // SymbolPeriod returns the time it takes to transmit a single symbol given the
-// current configuration parameters. It depends on Spread factor and Bandwidth.
+// current configuration parameters. It depends on Spreading factor and Bandwidth.
 func (cfg *Config) SymbolPeriod() time.Duration {
-	T_s := time.Second * time.Duration(cfg.SpreadFactor.ChipsPerSymbol()) /
+	T_s := time.Second * time.Duration(cfg.SpreadingFactor.ChipsPerSymbol()) /
 		time.Duration(cfg.Bandwidth.Hertz())
 	return T_s
 }
@@ -47,7 +47,7 @@ func (cfg *Config) SymbolPeriod() time.Duration {
 //   - CRC presence	(presence == longer)
 //   - Header type	(explicit == longer)
 //   - Coding rate	(proportional)
-//   - Spread factor	(inversely proportional)
+//   - Spreading factor	(inversely proportional)
 //   - Preamble length	(proportional)
 //   - Low data rate optimisation	(presence == longer)
 func (cfg *Config) TimeOnAir(payloadLength int) time.Duration {
@@ -58,10 +58,10 @@ func (cfg *Config) TimeOnAir(payloadLength int) time.Duration {
 	ih := int64(cfg.HeaderType)
 	ldr := int64(b2u8(cfg.LDRO))
 	cr := int64(cfg.CodingRate)
-	spread := int64(cfg.SpreadFactor)
+	sf := int64(cfg.SpreadingFactor)
 	// Page 31 SX1276IMLTRT SEMTECH | Alldatasheet.
-	Npayload := 8*int64(payloadLength) - 4*spread + 28 + 16*crc - 20*ih
+	Npayload := 8*int64(payloadLength) - 4*sf + 28 + 16*crc - 20*ih
-	div := 4 * (spread - 2*ldr)
+	div := 4 * (sf - 2*ldr)
 	// Apply Ceil and max with minimal branching.
 	if Npayload < 0 || div <= 0 {
 		Npayload = 0
@@ -77,7 +77,7 @@ func (cfg *Config) TimeOnAir(payloadLength int) time.Duration {
 	// time calculated.
 	Npayload += 8 + int64(cfg.PreambleLength) + 5
 	// Calculate LoRa Transmission Parameter Relationship page 28.
-	chipsPerSymbol := cfg.SpreadFactor.ChipsPerSymbol() // chips per symbol.
+	chipsPerSymbol := cfg.SpreadingFactor.ChipsPerSymbol() // chips per symbol.
 	return time.Second * time.Duration(Npayload*int64(chipsPerSymbol)) /
 		time.Duration(cfg.Bandwidth.Hertz())
 }
@@ -110,15 +110,15 @@ const (
 	CR4_8 CodingRate = 4
 )
 
-// SpreadFactor defines the number of chips per symbol. Higher spread factors
+// SpreadingFactor defines the number of chips per symbol. Higher spreading factors
 // imply longer transmission times but more robust communications.
-// The number of chips per symbol is 2^SF, so a spread factor of 8 takes twice
+// The number of chips per symbol is 2^SF, so a spreading factor of 8 takes twice
-// as long to transmit a symbol as a spread factor of 7.
+// as long to transmit a symbol as a spreading factor of 7.
-type SpreadFactor uint8
+type SpreadingFactor uint8
 
-// Common spread factors. Decide the number of chips per symbol.
+// Common spreading factors. Decide the number of chips per symbol.
 const (
-	SF5 SpreadFactor = iota + 5
+	SF5 SpreadingFactor = iota + 5
 	SF6
 	SF7
 	SF8
@@ -130,9 +130,9 @@ const (
 
 // ChipsPerSymbol returns the number of chips in a symbol. A chip is a subdivision
 // of a symbol in the frequency domain rather than the time domain, which is why
-// the units of this value is Hz, not Duration. A chip tells tells where to start
+// the units of this value is Hz, not Duration. A chip tells where to start
 // the frequency sweep for a symbol.
-func (sf SpreadFactor) ChipsPerSymbol() int64 {
+func (sf SpreadingFactor) ChipsPerSymbol() int64 {
 	return 1 << sf
 }
 

lora_test.go

@@ -22,13 +22,13 @@ func TestTimeOnAir(t *testing.T) {
 		{
 			desc: "LoRaWAN 240bytes", // https://www.thethingsnetwork.org/airtime-calculator
 			cfg: lora.Config{
-				Bandwidth:      lora.BW125k,
+				Bandwidth:       lora.BW125k,
-				Frequency:      915e6,
+				Frequency:       915e6,
-				SpreadFactor:   lora.SF7,
+				SpreadingFactor: lora.SF7,
-				HeaderType:     lora.HeaderExplicit,
+				HeaderType:      lora.HeaderExplicit,
-				CodingRate:     loraWANCodeRate,
+				CodingRate:      loraWANCodeRate,
-				CRC:            true,
+				CRC:             true,
-				PreambleLength: loraWANPreambleLength,
+				PreambleLength:  loraWANPreambleLength,
 			},
 			plen:     240,
 			expected: 394.5e3 * time.Microsecond,
@@ -36,13 +36,13 @@ func TestTimeOnAir(t *testing.T) {
 		{
 			desc: "LoRaWAN 5byte BW=500kHz", // https://www.thethingsnetwork.org/airtime-calculator
 			cfg: lora.Config{
-				Bandwidth:      lora.BW500k,
+				Bandwidth:       lora.BW500k,
-				Frequency:      915e6,
+				Frequency:       915e6,
-				SpreadFactor:   lora.SF7,
+				SpreadingFactor: lora.SF7,
-				HeaderType:     lora.HeaderExplicit,
+				HeaderType:      lora.HeaderExplicit,
-				CodingRate:     loraWANCodeRate,
+				CodingRate:      loraWANCodeRate,
-				CRC:            true,
+				CRC:             true,
-				PreambleLength: loraWANPreambleLength,
+				PreambleLength:  loraWANPreambleLength,
 			},
 			plen:     10,
 			expected: 15.4e3 * time.Microsecond,

sx127x/sx127x.go

@@ -81,7 +81,7 @@ type DeviceLoRa struct {
 func DefaultConfig(freq lora.Frequency) lora.Config {
 	return lora.Config{
 		Frequency:                freq,
-		SpreadFactor:             lora.SF7,
+		SpreadingFactor:          lora.SF7,
 		Bandwidth:                lora.BW125k,
 		CodingRate:               lora.CR4_5,
 		PreambleLength:           8,
@@ -103,7 +103,7 @@ func NewLoRa(bus SPI, cs, reset PinOutput) *DeviceLoRa {
 }
 
 var (
-	errBadSpread              = errors.New("bad spread factor")
+	errBadSpreadingFactor     = errors.New("bad spreading factor")
 	errSF6Implicit            = errors.New("SF6 can only be used with implicit header type") // Page 30: Implicit Header Mode.
 	errPreambleTooShort       = errors.New("preamble length too short")
 	ErrNotDetected            = errors.New("sx127x not detected")
@@ -116,6 +116,7 @@ var (
 	ErrCRC                    = errors.New("crc error")
 	ErrRxTimeout              = errors.New("rx timeout")
 	errImplicitPacketTooLarge = errors.New("packet length exceeds MaxImplicitPayloadLength")
+	errSyncWordTooLarge       = errors.New("sync word too long")
 )
 
 func (d *DeviceLoRa) InitLoRaMode() (err error) {
@@ -139,9 +140,9 @@ func (d *DeviceLoRa) InitLoRaMode() (err error) {
 
 func (d *DeviceLoRa) Configure(cfg lora.Config) (err error) {
 	switch {
-	case cfg.SpreadFactor < lora.SF6 || cfg.SpreadFactor > lora.SF12:
+	case cfg.SpreadingFactor < lora.SF6 || cfg.SpreadingFactor > lora.SF12:
-		err = errBadSpread
+		err = errBadSpreadingFactor
-	case cfg.SpreadFactor == lora.SF6 && cfg.HeaderType != lora.HeaderImplicit:
+	case cfg.SpreadingFactor == lora.SF6 && cfg.HeaderType != lora.HeaderImplicit:
 		err = errSF6Implicit
 	case cfg.PreambleLength < 6:
 		err = errPreambleTooShort
@@ -156,6 +157,8 @@ func (d *DeviceLoRa) Configure(cfg lora.Config) (err error) {
 		err = errors.New("MaxImplicitPayloadLength parameter must be set when working with implicit headers")
 	case cfg.TxPower > 20 || cfg.TxPower < -4:
 		err = errors.New("tx power not in operating range -4..20")
+	case cfg.SyncWord > 0xff:
+		err = errSyncWordTooLarge
 	}
 	if err != nil {
 		return err
@@ -189,7 +192,7 @@ func (d *DeviceLoRa) Configure(cfg lora.Config) (err error) {
 		return err
 	}
 	// TODO(soypat): Use default OCP?
-	err = d.setSyncWord(cfg.SyncWord)
+	err = d.setSyncWord(uint8(cfg.SyncWord))
 	if err != nil {
 		return err
 	}
@@ -197,7 +200,7 @@ func (d *DeviceLoRa) Configure(cfg lora.Config) (err error) {
 	if err != nil {
 		return err
 	}
-	err = d.setSpreadFactorConsistent(cfg.SpreadFactor)
+	err = d.setSpreadingFactorConsistent(cfg.SpreadingFactor)
 	if err != nil {
 		return err
 	}
@@ -706,7 +709,7 @@ func (d *DeviceLoRa) ReadConfig() (cfg lora.Config, err error) {
 	cfg.CodingRate = lora.CodingRate(cfg1>>1) & 0b111
 	cfg.HeaderType = lora.HeaderType(cfg1 & 1)
 	cfg2 := buf[1]
-	cfg.SpreadFactor = lora.SpreadFactor(cfg1 >> 4)
+	cfg.SpreadingFactor = lora.SpreadingFactor(cfg1 >> 4)
 	cfg.CRC = cfg2&0x4 != 0
 	// continuousMode = cfg2&0x8 != 0
 	cfg.PreambleLength = binary.BigEndian.Uint16(buf[3:])
@@ -715,7 +718,7 @@ func (d *DeviceLoRa) ReadConfig() (cfg lora.Config, err error) {
 	if err != nil {
 		return cfg, err
 	}
-	cfg.SyncWord = sync
+	cfg.SyncWord = uint16(sync)
 	// Read Frequency.
 	err = d.read(regFRF_MSB, buf[:3])
 	if err != nil {
@@ -864,9 +867,9 @@ func (d *DeviceLoRa) setFrequency(freq lora.Frequency) error {
 	return d.Write8(regFRF_LSB, freqReg[2]) // Write LSB last!
 }
 
-// setSpreadFactorConsistent sets the spreading factor and closely related parameters
+// setSpreadingFactorConsistent sets the spreading factor and closely related parameters
 // including Low Data Rate Optimization, DetectionOptimize, and DetectionThreshold.
-func (d *DeviceLoRa) setSpreadFactorConsistent(sf lora.SpreadFactor) (err error) {
+func (d *DeviceLoRa) setSpreadingFactorConsistent(sf lora.SpreadingFactor) (err error) {
 	err = d.setSpreadingFactor(sf)
 	if err != nil {
 		return err
@@ -889,9 +892,9 @@ func (d *DeviceLoRa) setSpreadFactorConsistent(sf lora.SpreadFactor) (err error)
 // It does not set parameters closely associated with the spreading factor such as
 // the Low Data Optimization, the Detection threshold, Detection Optimize and the
 // Symbol Timeout.
-func (d *DeviceLoRa) setSpreadingFactor(sf lora.SpreadFactor) error {
+func (d *DeviceLoRa) setSpreadingFactor(sf lora.SpreadingFactor) error {
 	if sf < 6 || sf > 12 {
-		return errBadSpread
+		return errBadSpreadingFactor
 	}
 	const sfMask = 0b111 << 4
 	return d.writeMasked8(regMODEM_CONFIG_2, sfMask, uint8(sf)<<4)

sx128x/sx128x.go

@@ -31,7 +31,7 @@ type DeviceLoRa struct {
 func DefaultConfig(freq lora.Frequency) lora.Config {
 	return lora.Config{
 		Frequency:                freq,
-		SpreadFactor:             lora.SF9,
+		SpreadingFactor:          lora.SF9,
 		Bandwidth:                lora.BW1625k,
 		CodingRate:               lora.CR4_5,
 		PreambleLength:           12,
@@ -90,13 +90,13 @@ func (d *DeviceLoRa) Configure(config lora.Config) error {
 	if err != nil {
 		return err
 	}
-	err = d.setModulationParamsLoRa(config.SpreadFactor, config.Bandwidth, config.CodingRate)
+	err = d.setModulationParamsLoRa(config.SpreadingFactor, config.Bandwidth, config.CodingRate)
 	if err != nil {
 		return err
 	}
 
 	// special register setting depending on spreading factor chosen
-	switch config.SpreadFactor {
+	switch config.SpreadingFactor {
 	case lora.SF5, lora.SF6:
 		d.writeRegister(regSpreadingFactorAdditionalConfiguration, []byte{0x1E})
 	case lora.SF7, lora.SF8:
@@ -418,7 +418,7 @@ func (d *DeviceLoRa) setBufferBaseAddress(txBase uint8, rxBase uint8) error {
 	return err
 }
 
-func (d *DeviceLoRa) setModulationParamsLoRa(spreadingFactor lora.SpreadFactor, bandwidth lora.Frequency, codingRate lora.CodingRate) error {
+func (d *DeviceLoRa) setModulationParamsLoRa(spreadingFactor lora.SpreadingFactor, bandwidth lora.Frequency, codingRate lora.CodingRate) error {
 	err := d.waitWhileBusy(time.Second)
 	if err != nil {
 		return err