Author Topic: AHT10 Datasheet and registers??  (Read 1658 times)

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Offline chimera_786

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AHT10 Datasheet and registers??
« on: August 23, 2021, 03:35:39 am »
Hi there!

So i bought my self an AHT10 sensor and started playing around with it.

I learnt the quirks and limitations of the device by seeing other people example code (Python, C++, java etc). Its working on my set up (Pi Zero w/ rasbian lite) but the one thing thats bothering me is:

how did folks discover the hidden registers that need to be commanded for calibration (i.e. initialization)? They are are NOT in AHT10 datasheet? (https://server4.eca.ir/eshop/AHT10/Aoso ... aft_0c.pdf.

The only place they are mentioned is in the AHT20 datasheet but no where is it communicated that AHT10 shares the AHT20 memory mapping.
https://files.seeedstudio.com/wiki/Grov ... 0-4-16.pdf

I mainly found them, as i mentioned earlier, by checking other peoples code. These links may serve as research bank for those people who will inevitably come here with the same confusion as I ran into

https://github.com/gejanssen/aht10-pyth ... ython3.py https://tasmota.github.io/docs/AHT1x/[/url]
[/url]https://elchupanibrei.livejournal.com/53764.html[/url]
[/url]http://www.espruino.com/modules/AHT10.js[/url]


Looking forward to hearing back from those hardworking folks who deciphered the cryptic memory mapping of AHT10.
 

Offline TooOldForThis

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Re: AHT10 Datasheet and registers??
« Reply #1 on: October 20, 2021, 09:27:53 pm »
I found a copy of the manual here:  https://kaimte.com/product/details/aosong/aht10.html
Aosong doesn't have it on their website. That won't help sales.
 

Offline DrG

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Re: AHT10 Datasheet and registers??
« Reply #2 on: October 23, 2021, 04:12:01 pm »
I got one of these....seems like I collect humidity sensors as a hobby :)

Make sure you have seen this comment:

3, Only a single AHT10 can be connected to the I 2 C bus and no other I 2 C devices can be connected .

Good luck with investigations and all, but for me, that comment sent the unit into a drawer or box or somewhere.
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Offline TooOldForThis

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Re: AHT10 Datasheet and registers??
« Reply #3 on: October 28, 2021, 08:19:52 pm »
I don't seem to be very good at following instructions.  I have two AHT10's on the same I2C bus as a LCD module and everything runs fine.  The address of the AHT10 can be changed from 0x38 to 0x39 by pulling the ADR pin to Vcc.   The manual was translated from Chinese to English (almost) so may have lost nuance.  I suspect the "Only a single AHT10 can be connected..." part meant to say "For the best accuracy, only a single AHT10 should be connected..."
Activity on the bus will cause a small amount of self heating in any i2c device. 
 

Offline DrG

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Re: AHT10 Datasheet and registers??
« Reply #4 on: October 29, 2021, 06:06:10 pm »
I don't seem to be very good at following instructions.  I have two AHT10's on the same I2C bus as a LCD module and everything runs fine.  The address of the AHT10 can be changed from 0x38 to 0x39 by pulling the ADR pin to Vcc.   The manual was translated from Chinese to English (almost) so may have lost nuance.  I suspect the "Only a single AHT10 can be connected..." part meant to say "For the best accuracy, only a single AHT10 should be connected..."
Activity on the bus will cause a small amount of self heating in any i2c device.

I don't know, but don't care to deal with it. I don't ever remember seeing an I2C device that said no other I2C devices can be attached. Maybe they did mean "at the same address" and it got lost in translation.

Why do you think that activity of another device on the bus would cause self heating to the extent of decreasing accuracy?
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Offline DrG

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Re: AHT10 Datasheet and registers??
« Reply #5 on: October 29, 2021, 06:25:05 pm »
So, to learn something, or just for S&G, I did a bit of reading about self-heating of an I2C device because of activity on the bus and couldn't really find anything at all (ok, I did not look that long). There is a decent discussion on the matter of over-heating in a TMP116/117 sensor. https://www.ti.com.cn/cn/lit/pdf/snoa986 But, the discussion concerns the size of the pull up resistors and their location near the chip (drawing current and producing heat), and frequently accessing the chip (increasing the current draw/per unit of time) - nothing about activity on the bus for other chips. Now, if you had two sensors right next to each other and frequently activated one of them, you could heat up the other externally...at least in principle.

But heating up the one because of any activity on the bus seems pretty far-fetched to me, especially for something like that to be mentioned in *that* data sheet, but I could be wrong. Don't know and I still tend to think that if there was a mis-translation it probably had to do with warning about two (or more) devices using the same address.

In any even, while I am unconvinced about self-heating to the extent of decreasing because of any other activity on the bus. Nevertheless, I am glad that you contributed your observation of using two devices and changing the address of one and having no apparent problems.

« Last Edit: October 29, 2021, 07:20:27 pm by DrG »
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