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Add Airtime Calcultion #476

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Add Airtime Calcultion #476

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DiegoDVG Jun 1, 2021
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DiegoDVG Jun 1, 2021
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30 changes: 29 additions & 1 deletion src/LoRa.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -565,7 +565,7 @@ void LoRaClass::setCodingRate4(int denominator)
} else if (denominator > 8) {
denominator = 8;
}

_coderate = denominator; // save coderate
int cr = denominator - 4;

writeRegister(REG_MODEM_CONFIG_1, (readRegister(REG_MODEM_CONFIG_1) & 0xf1) | (cr << 1));
Expand Down Expand Up @@ -751,4 +751,32 @@ ISR_PREFIX void LoRaClass::onDio0Rise()
LoRa.handleDio0Rise();
}

double LoRaClass::Airtime_Message()
{
int SF = getSpreadingFactor();
int BW = getSignalBandwidth();
int H = _implicitHeaderMode; // save header mode
int PL = readRegister(REG_PAYLOAD_LENGTH);
int DE = 0;
if (((BW == 125E3) && ((SF == 11) || (SF == 12))) ||
((BW == 250E3) && (SF == 12)))
{
DE = 1;
}
else
{
DE = 0;
}

int CR = (readRegister(REG_MODEM_CONFIG_1) & 0xf1) + 4;

double Tsym = pow(2, SF) / (BW)*1000;
double Tpreamble = (8 + 4.25) * Tsym;
int PrePay = ceil((8.0 * PL - 4.0 * SF + 28 + 16 - 20 * (1 - H)) / (4.0 * (SF - 2.0 * DE))) * (CR);
int payloadSymbNb = 8 + _max(PrePay, 0);
double Tpayload = payloadSymbNb * Tsym;
double Tpacket = Tpreamble + Tpayload;
return Tpacket;
}

LoRaClass LoRa;
3 changes: 2 additions & 1 deletion src/LoRa.h
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Original file line number Diff line number Diff line change
Expand Up @@ -93,7 +93,7 @@ class LoRaClass : public Stream {
void setSPIFrequency(uint32_t frequency);

void dumpRegisters(Stream& out);

double Airtime_Message();
private:
void explicitHeaderMode();
void implicitHeaderMode();
Expand Down Expand Up @@ -123,6 +123,7 @@ class LoRaClass : public Stream {
int _implicitHeaderMode;
void (*_onReceive)(int);
void (*_onTxDone)();
int _coderate;
};

extern LoRaClass LoRa;
Expand Down