Esp-idf: Internal Temp Sensor API (IDF-90)

[forthlightning]

I am wondering when there will be support for the internal temperature sensor?

I'm hoping to do some internal diagnostics on my project, please let me know!

[vitasimek]

Hi,
I am also interested in this. I have read all the doc available, I hope, and I think it is (?) the part of the ADC stuff, that has been already merged there in the 1.0 release. Is it true? Well, if so, I can try to help to hack it to get it working somehow.

[forthlightning]

Yeah i looked through the code and it looks like they have the registers all mapped out here

Not sure how that translates into a nice get_temp() function but it's something!

[vitasimek]

Well, I don't know exactly if this matters, but I've found this video about ESP32 beta and ADC1 by rudi: https://www.youtube.com/watch?v=hVLhqiNS3vU

It looks like he may to know how it works. Please correct me if I am wrong.

[vitasimek]

And the investigation continues to here: http://esp32.com/viewtopic.php?f=2&t=494&p=2121#p2121

[vitasimek]

There has to be some mechanism for starting ADC conversion, waiting and then reading the result from some register. I have found just this, that maybe could be some clue: SARADC_SAR_START_FORCE_REG there in the ulp.c file.

[projectgus]

The SAR ADC code is in code review right now, so there will be answers very soon! Sorry for the delay on this one.

[vitasimek]

I just got working the rudi's example with ADC :) :+1:

@projectgus: I know you are working really really hard and it deserves big respect. Thank you for your effort.

Is there some register address (like ADC1_GPIO34) that is associated with the onboard temperature sensor?

[comcat]

on chip sensor, try this: http://wiki.jackslab.org/ESP32_Onchip_Sensor

ADC: http://wiki.jackslab.org/ESP32_ADC

[vitasimek]

Hi Jack,
your example just works! :)
The functions are already there in the libs, the only thing is to define them as they would been defined there in the header file.

Thank you.

[yschaeff]

Also, while you are at it fix the spelling. temprature_sens_read() should read temperature_sens_read(). I was wondering why my greps didn't yield any result.

[forthlightning]

bump :D

[HubbyGitter]

I recommend against using temprature_sens_read(). Use the code from test_tsens.c (at least as a basis) instead.

Regarding temprature_sens_read():

• It is an undocumented an unofficial function.
• Its initialisation sequence is not clean.
• It yields readings which deviate from that of the implementation in test_tsens.c, presumably due to a very fast conversion clock. However, you won't get a faster reading than with the code in test_tsens.c.
• It uses busy waiting without you even knowing.

Please refer to this discussion which describes more background and a possible modification to the code in test_tsens.c.

[HubbyGitter]

As requested in the discussion mentioned in my previous comment, I'm adding the following information here.

The following two screenshots show a comparison of TSENS readings via temprature_sens_read() ("n/a 2") and via test_tsens.c code ("it"), as well as a precision external sensor (BME280). All data points are taken "simultaneously" and posted as a set. And yes, the fan which I used for the cooling disturbed the WiFi so not all data points were captured here towards the right side.

I think this shows that readings via temprature_sens_read() have significantly more jitter, generally tend to "swing" / overreact, and have problems reaching higher values -- also supported by past observations. (Screenshot 1 starts directly after a flashing procedure which led to increased chip temperature.)

[mvadu]

@me-no-dev Its been 6 months since last activity in this topic. Is there any standard API (documented, usable in Arduino) that espressif recommends to make use of the temp sensor?

[projectgus]

Unfortunately due to performance issues the temp sensor feature is no longer supported.