Hi,
I would like to create a simple temperature and pressure meter with ESP32. The main topic here is an issue about ADC conversion on ESP32. I've got PT1000 temp so far where I tried couple of things to test if it's suitable for my needs. But there is a challange with ADC converter. The raw analog output from ESP gives me values all over the place even the voltage on analog pin from temp sensor is stable. I've used voltage divider with 1k ohm resistor.
Tomorrow I'm going to grab a VDO sensor and I think the story will be same. Do you have any idea if there is some ADC convertor like MAX31865 for PT1000 sensors but for VDO? It seems like ADC built-in convertor in ESP is quite garbage.
Thanks for the help.
Tell us what a VDO sensor is. I'm familiar with VDO automotive gauges. It that what you are talking about?
Correct, I'm talking about this one.
https://vdo-webshop.nl/en/temperature-sensors/4126-continental-vdo-oil-temperature-sender-150°c-m14-4103590682789.html
A suitable choice might be the Adafruit ADS1015 12-Bit ADC. It will operate at 3V3 so you can use it without level converters with your ESP32 and interfaces via IIC. It has four single ended channels in case you need to measure additional voltages.
The people at Adafruit say "We like this ADC because it can run from 2V to 5V power/logic, can measure a large range of signals and it's super easy to use. It is a great general purpose 12 bit converter."
While you could use an ADC with more bits of resolution, the thermistor sensor you indicated is not extremely accurate and more resolution would be pointless.
Yes, happily!
It has a range of resistance values not a million miles away from another sensor we heard of the other day.
Well that turns out to be another story altogether. Check the thread.
Great, thank you.
I just need something that will work with accuracy -+1 °C.
In the end my intention is to build a unit for atmospheric pressure, oil pressure+temp and probably 2x air temp sensors without the need of gauges. I really like idea of one digital round gauge but it is not suitable for me. So I'm going with Android app for now.
Unfortunately, the sensor doesn't have that good a tolerance. For that sort of accuracy you will have to calibrate it yourself.
If you truly need 1ºC accuracy, you might want to consider a different sensor.
A temperature sensor with +-1ºC would be a platinum RTD. Finding one that will fit your M14 x 1.5 location might be a challenge. I just recently made a custom thermocouple sensor for a project that might give you some ideas.
I drilled a 2.05 mm hole in a brass set screw and thermal epoxied the sheathed thermocouple inside.
Since it looks like you need a shoulder for a seal, you might use a brass hex bolt and a similar RTD sensor.
Do you have any recommendations for a good thermocouple? I was only able to find some PT1000 and PT100 for 2€.
Thermocouple or platinum RTD?
Thermocouples don't necessarily meet your accuracy spec. Adafruit have K-type both bare and with a stainless steel sheath. thermocouple
PT100/PT1000 like in the lower image is from Adafruit as well. Not 2€. though, $12.
Pt RTD
Sorry that I have so many question but if somebody already did this type of stuff then I'm more willing to just listen how to do it. This is my third project, second and first were much simpler (LED BT controller via app, CD changer simulator for car radio).
I was today at shop for VDO and it was some no name stuff in the all so I left it there.
With the -+1 °C I meant more likely spread and I'm counting with calibration everytime. That is not a problem for me. Local shops in my are has only some China knock offs but I was able to find offical distributor for Adafruit here too.
So I should grab PT100 with ADS1015 or use MAX31865 instead?
The MAX31865 is a better choice for the RTD.
If you need an ADC with better linearity than the ESP32 then the ADS1015 would be a good option.
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Where is the reference to this information!
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