Pin mapping of CTs for Photon

Hardware
1

I was wondering how pin assignments were made for reading the CTs, especially in something like the Particle Photon? I understand there is an EmonLib.h library ported to Photon, but how does that library know pin 2 is for voltage, and pin 1 is for current?

emon1.voltage(2, 234.26, 1.7); // Voltage: input pin, calibration, phase_shift
emon1.current(1, 111.1); // Current: input pin, calibration.

Assuming that the inclusion of application.h and the EmonLib.h port does this remapping behind the scenes, would it be safe to say that these are A0-A8, and just a matter of adding more of the same line above for current, only changing the pin and calibration to match the physcial inputs? I apologize in advance, I just wish to make sure I understand and also not blow up my Photon.

2

It doesn’t. You are telling it exactly that with

The allocation of pins to logical channels for the emonTx V2 is done in emonLib.cpp, in

EnergyMonitor::voltageTX(double _VCAL, double _PHASECAL)
and
EnergyMonitor::currentTX(unsigned int _channel, double _ICAL)

if you use

EnergyMonitor::voltage(unsigned int _inPinV, double _VCAL, double _PHASECAL)
and
EnergyMonitor::current(unsigned int _inPinI, double _ICAL)

then you define the analogue input to use - not the physical pin number, but the Analogue input number (the name inPin is somewhat misleading).

You won’t blow up your ADC/input if your are reading - it’s only when you write to a pin that’s being fed a voltage that you will risk damaging the input, and possibly the whole device.

3

The use of inPin was what got me. I saw the second example you provided in the emonLib.cpp ported to Photon, but was expecting to see A0, A1, A3, etc… for mapping to a pin. Thank you.