hx711 module design fault fix

[konosubakonoakua]

Solution: Use A wire to connect E- and GND

I read the datasheet of HX711, and found a design fault of the hx711 moudule in the market.

In the picture above, we can see that the pin-5 is AGND,
The picture below shows the recommended application in it's datasheet.

It should be connected to GND, but the module dosen't do that.

But we can still use the module, because the current can flow back via SCK pin, when it's low level.
However, it's not stable.

[amotl]

Dear @konosubakonoakua,

thanks for bringing this up. Many breakouts out there are of poor quality, see also [1] and [2]. It's sad but true. Specifically, we also published a recommendation about how to apply this hardware fix at [3]. However, please take into account that we waive any kind of responsibility for damages. Enjoy!

Cheers,
Andreas.

[1] https://community.hiveeyes.org/t/analyse-und-diskussion-um-eine-korrekte-integration-des-hx711/2802
[2] https://community.hiveeyes.org/t/stromversorgung-hx711/893
[3] https://community.hiveeyes.org/t/stromversorgung-hx711/893/17

[amotl]

Hi Bogdan,

while this topic is not about an issue of the library but about the hardware, the information here is still very valuable for the community. In that manner, I suggest to add a tag called information to this issue and keep it open for the sake of discoverability. I will delete this comment afterwards.

With kind regards,
Andreas.

[bogde]

@amotl I was just looking at this today and while i can confirm the reported issue (E- AGND not connected to GND), actually connecting AGND to GND didn't make a significant difference in my case. Nevertheless, it's something to keep in mind and something that can potentially help others. I added a label to this issue, I'm not sure if that's what you meant by tag, let me know.

I was also thinking to add this to the FAQ file I just created, especially if @konosubakonoakua agrees to let me use his post and images.

I was also looking at #148
I know it's been some time since that was posted but i'd appreciate your thoughts on it. I've been doing tests lately and, as expected, that does make readings more stable. I was thinking to add some new methods that would allow the user to basically configure the library to set a number of bits to 0 in the read() function. Something like:

data[0] = data[0] && 128

[konosubakonoakua]

@bogde sure, you can use them freely

[X-Ryl669]

data[0] = data[0] && 128

You meant data[0] = data[0] & 128 ? Else it means data[0] == 1 if non zero before.

[bogde]

yes, that's what i meant but the change was never implemented

[amotl]

Hi Bogdan,

I was also thinking to add this to the FAQ file I just created, especially if @konosubakonoakua agrees to let me use his post and images.

I think you can also use the images at [1] shared by @msweef if you like them.

With kind regards,
Andreas.

[1] https://community.hiveeyes.org/t/stromversorgung-hx711/893/17