Hook up multiple hx711 amplifiers to 16 channel multiplexer

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im using 12-16 single point load sensors each going to an hx711. I may be to use two sensors for each hx711 but not sure. But my primary question is that Im wondering which multiplexer breakout board would be best, ultimately to go to a raspberry pi gpio. SparkFun Analog/Digital MUX Breakout - CD74HC4067 or SparkFun 16 Output I/O Expander Breakout - SX1509. The hx711 has two output wires so it seems like the latter but im not sure ? any advice would be appreciated. Thanks

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I’d probably go with the latter as well, but they are cheap enough that I’d order both and see which I prefer in-action

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After more research I went with the Qwiic scale (16) Qwiic mux breakout (2) and redboard plus. I should beable to handle everything with that. but hopefully i can condence it down in the future.

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Were you able to get this working properly? Looking to connect 8 HX711 (and accompanying load cells) to a single board but I had read there were some issues in getting multiple boards on the i2c bus as the address was not configurable? Maybe it was just that there were no jumpers to change/set the address on the board, but was this an issue that came up for you? relatively new to working w/ i2c bus as well so it’s possible Im ignorant of something basic.

thx.

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The issue is that the qwiic scale has a hardware-defined i2c address, the way to workaround that and implement several on one setup is to use the mux they mentioned which allows 8 per mux

For the hx711 you’d want to use the combinator https://www.sparkfun.com/products/13878 which allows up to 4 hx711’s to be hooked up at once (so you’d need 2 for 8 sensors)

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Thank you sir.

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@TS-Russell , hoping you can clarify just a tiny bit. What is the combinator for? Because I’m measuring 8 totally distinct things, my thinking would be get the multiplexer, 8 HX711 amplifiers, each one attached to it’s own load cell (8x load cells) and that would be the path to measure 8 unrelated items. As I read the combinator, it seems it’s more for a single measurement but with a number of load cells. Or am I incorrect in my understanding?

thx for your time,
ray

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HX711 has clock and data lines but it’s not I2C/Quiic. A mux like BOB-09056 will work to select the HX711 data line you want to talk too. You can combine all the clock lines together to save pins, or use a second mux for the clock.

The combinator is for connecting 4 three wire load sensors to one HX711, I think TS-Russell got that backwards by accident. If you’re using a single four wire load cell, you don’t need the combinator.

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Thanks for the info. Would there be any reason to multiplex the clock lines as well as the data side? Is there anything you think I’d be sacrificing only multiplexing the data line?

Thanks.

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If for some reason shared clock lines weren’t working. I’ve shared clock on 2 or 3 HX711’s at a time and that worked but I’ve not tried more than that.