EmonTH pulse counter and external Temp sensor

Can the EmonTH have a pluse counter and external temperature sensor (ds18b20) connected at the same time?



Just checked mine. I have 3 temp sensors and I pulse counter attached to my Emonth


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They use different inputs: the temperature sensors are on the 1-wire interface, the pulse is on a digital (interrupt) input.

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all sorted thank you. I have wired the pluse counter and temperature sensor at the same time.

I am seeing some strange readings on the graphs, does anyone have any pointers?

What is the value of those spikes - 85°C by any chance? This might indicate that the sensor has been powered but not commanded to measure (‘convert’) the temperature. It might be a symptom of an intermittent power supply to the sensor. The DS18B20 data sheet has more details - it’s the power-on reset value of the temperature register, I presume that number was chosen as it is the upper limit of the ±0.5°C tolerance band.

Hi @Robert.Wall

they look like +85. I spose one solution is to skip anything >50 are they any others?


I would first check your batteries - if there’s a high resistance contact, the high current pulse during transmit could well do funny things, as of course would a dry soldered joint or a not tight terminal screw. (You’ve not ‘tinned’ the wires, nor clamped onto the insulation?)

The batteries are energiser lithium “AA” voltage is showing as 3.2v its a new EmonTH from the store a few weeks ago and connections look ok/feel ok.

I’m afraid I don’t have a recent (RFM69CW) emonTH, so there’s little point in me trying to run a test.

I’d wonder whether the power saving efforts are too aggressive, what I’d do to start debugging this is to power the TH from a programmer, and firstly check that you are still getting “85” values, then bit at a time take out the power-saving code. If you can check for glitches in the power to the DS18B20, so much the better - because I’m guessing that’s the problem, but it’s not guaranteed.