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[SX127x] Added public method to convert from bytes to symbols

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This commit is contained in:
jgromes 2023-11-12 13:28:06 +01:00
parent 140d35af81
commit c170bc096f
2 changed files with 39 additions and 16 deletions
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47
src/modules/SX127x/SX127x.cpp
View file

@ -1231,28 +1231,45 @@ int16_t SX127x::variablePacketLengthMode(uint8_t maxLen) {
return(SX127x::setPacketMode(RADIOLIB_SX127X_PACKET_VARIABLE, maxLen));
}
float SX127x::getNumSymbols(size_t len) {
// get symbol length in us
float symbolLength = (float) (uint32_t(1) << this->spreadingFactor) / (float) this->bandwidth;
// get Low Data Rate optimization flag
float de = 0;
if (symbolLength >= 16.0) {
de = 1;
}
// get explicit/implicit header enabled flag
float ih = (float) this->mod->SPIgetRegValue(RADIOLIB_SX127X_REG_MODEM_CONFIG_1, 0, 0);
// get CRC enabled flag
float crc = (float) (this->mod->SPIgetRegValue(RADIOLIB_SX127X_REG_MODEM_CONFIG_2, 2, 2) >> 2);
// get number of preamble symbols
float n_pre = (float) ((this->mod->SPIgetRegValue(RADIOLIB_SX127X_REG_PREAMBLE_MSB) << 8) | this->mod->SPIgetRegValue(RADIOLIB_SX127X_REG_PREAMBLE_LSB));
// get number of payload symbols
float n_pay = 8.0 + RADIOLIB_MAX(ceil((8.0 * (float) len - 4.0 * (float) this->spreadingFactor + 28.0 + 16.0 * crc - 20.0 * ih) / (4.0 * (float) this->spreadingFactor - 8.0 * de)) * (float) this->codingRate, 0.0);
// add 4.25 symbols for the sync
return(n_pre + n_pay + 4.25f);
}
uint32_t SX127x::getTimeOnAir(size_t len) {
// check active modem
uint8_t modem = getActiveModem();
if (modem == RADIOLIB_SX127X_LORA) {
// Get symbol length in us
// get symbol length in us
float symbolLength = (float) (uint32_t(1) << this->spreadingFactor) / (float) this->bandwidth;
// Get Low Data Rate optimization flag
float de = 0;
if (symbolLength >= 16.0) {
de = 1;
}
// Get explicit/implicit header enabled flag
float ih = (float) this->mod->SPIgetRegValue(RADIOLIB_SX127X_REG_MODEM_CONFIG_1, 0, 0);
// Get CRC enabled flag
float crc = (float) (this->mod->SPIgetRegValue(RADIOLIB_SX127X_REG_MODEM_CONFIG_2, 2, 2) >> 2);
// Get number of bits preamble
float n_pre = (float) ((this->mod->SPIgetRegValue(RADIOLIB_SX127X_REG_PREAMBLE_MSB) << 8) | this->mod->SPIgetRegValue(RADIOLIB_SX127X_REG_PREAMBLE_LSB));
// Get number of bits payload
float n_pay = 8.0 + RADIOLIB_MAX(ceil((8.0 * (float) len - 4.0 * (float) this->spreadingFactor + 28.0 + 16.0 * crc - 20.0 * ih) / (4.0 * (float) this->spreadingFactor - 8.0 * de)) * (float) this->codingRate, 0.0);
// get number of symbols
float n_sym = getNumSymbols(len);
// Get time-on-air in us
return ceil(symbolLength * (n_pre + n_pay + 4.25)) * 1000;
return ceil(symbolLength * n_sym) * 1000;
} else if(modem == RADIOLIB_SX127X_FSK_OOK) {
// Get number of bits preamble
float n_pre = (float) ((this->mod->SPIgetRegValue(RADIOLIB_SX127X_REG_PREAMBLE_MSB_FSK) << 8) | this->mod->SPIgetRegValue(RADIOLIB_SX127X_REG_PREAMBLE_LSB_FSK)) * 8;

8
src/modules/SX127x/SX127x.h
View file

@ -818,7 +818,6 @@ class SX127x: public PhysicalLayer {
\brief Interrupt-driven receive method. DIO0 will be activated when full valid packet is received.
\param len Expected length of packet to be received, or 0 when unused.
Defaults to 0, non-zero required for LoRa spreading factor 6.
If non-zero for LoRa spreading factor > 6, RxSingle is used and value must be given in symbols.
\param mode Receive mode to be used. Defaults to RxContinuous.
\returns \ref status_codes
*/
@ -1046,6 +1045,13 @@ class SX127x: public PhysicalLayer {
*/
int16_t variablePacketLengthMode(uint8_t maxLen = RADIOLIB_SX127X_MAX_PACKET_LENGTH_FSK);
/*!
\brief Convert from bytes to LoRa symbols.
\param len Payload length in bytes.
\returns The total number of LoRa symbols, including preamble, sync and possible header.
*/
float getNumSymbols(size_t len);
/*!
\brief Get expected time-on-air for a given size of payload.
\param len Payload length in bytes.