4-20 mA Unit with wemos S2 mini ESP32

[robski]

@obstbauer try calibration function based on what you see with multimeter

[obstbauer]

@robski thanks for the answer

so you mean if I measure with multimter 4.0 mA (which is true for the sensor) and the unit shows me 7.2 mA I should set the calibrated value to 4.0 ?

Because this is not mentioned anywhere in a readme file or manual or in the description of the device, and it is not made in the example file at github
but I am a beginner....

[robski]

@obstbauer thats what i did with mine initially, calibrate with known current value

[obstbauer]

@robski ok I think I found it:

thank you I will try tomorrow

[robski]

@obstbauer yeah thats the registers table, I used Uiflow2 with calibration block but you are using not M5Stack controller I see

[obstbauer]

@robski what value do you take for "index" in the function

void MODULE_4_20MA::setCalCurrent(uint8_t index, uint16_t value)

[robski]

@obstbauer haven't used index value

in uiflow2 ..ain4_20ma_0.set_cal_current(10) to set 10mA
ain4_20ma_0.set_cal_current(20) to set 20mA

[obstbauer]

@robski yes maybe in uiflow2 but the function for the c program asks for an index and a value

[obstbauer]

I see really strange behaviour and I don't know the reason and I get no answers from the support.....
The example code from M5Stack say that the currentvalue should be divided by 100:

canvas.printf("Current:%.2fmA", (float)(meter.getCurrentValue(0)) / 100.0);

The values I get I have to divide by 10 to get the right current in mA.... and the other issue is that I can only use half of the measurement range, at 12.5 mA the ADC sends 65520...

maybe someone has an idea ?

[obstbauer]

change to a raspberry PI4 seems to be no solution too.....
it woud be nice if there would be a better documentation for people who want to use the units outside the m5stack universum....

[robski]

@obstbauer this is uiflow example with raw value and float too

[obstbauer]

thank you, but I am still not able to read out or to set the cal current
M5Stack support doesn`t answer my mails... and it seems that there is nobody from the company around here, I think I will change to another board with better support

[robski]

@obstbauer TBH if you are using M5Stack modules/units with not M5Stack controllers maybe its worth to have at least one M5Controller (atom?stick? )to be able to check module functionality