Kees - Is there a repositor with examples on us...
Is there a repository with examples on using the HAMLET? I am looking at https://docs.hatlabs.fi/halmet/docs/ and https://github.com/hatlabs/HALMET-example-firmware/tree/main. I was wondering if there were more projects/examples. I just ordered a HAMLET and want to start digitizing my engine RPM reading (Volvo Penta MD2020D) while maintaining the readings on the existing analog gauge, as well as my fuel tank sensor (and also remain the analog gauge). As well as a resistive coolant temp sensor 1 wire (450-23 ohm).
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It's just the example firmware repo at the moment, unless some people have published their own applications. Feel free to ask any questions, though!
The high resistance end of the coolant temp sensor is beyond HALMET's measurement range - let's hope the 300-450 ohm section is not required!
Thanks Matti. I just read that indeed. But if I would combine that one with an analog gauge in parallel too then i would be good because i dont need to use CCS. Correct? Good excuse to also install an analogue gauge for that one next to the tank+rpm. The wiring is even already there out of the box from volvo penta, from motor to panel, just not the gauge itself.
Ah yes, of course!
I managed testing RPM simulation and also Analogue Voltage input so far coming into my SignalK. So succeeded so far with Hamlet. Again a great product from you (i already had sailorhat and sh-esp32 works very well too). Thanks!. I used / adapted the firmware example of Hamlet for it.
Now I also want to add a digital temperature sensor to the one wire on the HALMET. I have checked this repo: https://github.com/hatlabs/SH-ESP32-onewire-temperature. I am kind of stuck as I find it hard to merge that in the main.cpp of the HALMET firmware. Is there by any chance an example somewhere where someone combined both the example firmware and added the onewire temperature integration too?
And also looking for how to setup an analog temp sensor based on resistance (in combination with gauge), i can only see examples in the firmware of tank sensors but not temp sensors.
A wait, let me try to explore some forks like here that includes one-wire: https://github.com/kristianschneider/HALMET-example-firmware/blob/main/src/main.cpp
AFAIK ”piggybacking” resistive sensors (or at least thermistors) without affecting the analog gauge reading is nearly impossible, or at least very complicated, if accuracy is a thing
Any one has ever got a resistive temp sensor working on the analogue input without current sense? If i am looking at halmet_analog.cpp i can only find tank sensor. Would be great to have some examples.
Why? It's just a voltage measurement. Of course, it gets more complicated if your gauge is using the system nominal 12V (that is anything but 12V) as a reference; then you need to measure the reference voltage as well.
Hmm, so let's say you have a single thermistor, and your analog gauge feeds it nominal 12V and measures the voltage drop. Now you want to get the same reading to your ESP32 device without adding another thermistor or without removing the analog gauge. How would you wire your ESP32 in order to get a measurement that would not affect the reading on the analog gauge?
You measure the voltage over the thermistor. The gauge can measure the resistance either using constant current or constant voltage. The former has a linear relationship with the resistance, with the latter you need to get a few points to estimate the curve.