Add packetSnrRaw method to avoid floating-point
#570
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Some microcontrollers cannot use their floating-point coprocessor during interrupts (e.g. ESP32) which means they can't use the packetSnr method. packetSnrRaw allows the user to forgo the `* 0.25` in such cases
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Could you use bit shift instead of the division - https://stackoverflow.com/questions/13577174/can-anyone-explain-why-2-shift-means-divided-by-4-in-c-codes? |
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My thought is to leave it up to the user. I would like to keep the full precision of it, but I'd accept the loss of 2 bits. |
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This patch is motivated by a well known (#459, #460) limitation, that ESP microcontrollers can't use
float LoRa.packetSnr()in ISR because that method performs a floating point operation.My proposed solution is to add a method
int LoRa.packetSnrRaw()that returns theREG_PKT_SNR_VALUEregister as anintunmodified, rather than as a float divided by 4. I've written documentation for it noting that since it forgoes the division by 4, its value is 4 times the actual SNR.