I don't have a background in electrical engineering, I'm just an hobbyist, so my knowledge of electrical circuits is very limited.
I need to wire a 10Kg load cell to a HX711 amplifier, and then to an ESP32 board.
These are the specs for the HX711 board:
Differential input voltage: ±40mV ( Full-scale differential input voltage is ± 40mV ) Data accuracy: 24-bit ( A/D converter chip ) Refresh frequency: 80 Hz Operating Voltage: 5V DC (2.6V ~ 5.5V) Operating current: <10 mA Operation supply voltage range: 2.7V ~ 5.5V Operation temperature range: -40 ~ +85℃ Size: 33mm x 20mm
I will need to run it at 80Hz.
If I supply 5V to this board, do the signals coming from DT and SCK also come at 5V (max)?
If so, what can I do to lower them to 3.3V? Will a 1K resistor in each line suffice or is there more to it?
I would appreciate any help.
Best is to use voltage level convertors. These exists in 4 or 8 lines.
You can make the HX711 permanent 10SPS/80 SPS by connecting the rate pin to VCC/GND. My HX711 library supports switching between 10 and 80 SPS if you connect the rate to a digital pin.
Based on the topic title I have a little doubt that you are using an Arduino Nano ESP32 and therefore your topic has been moved to a more suitable location on the forum.
The Arduino Nano ESP32 category is only for problems with the Arduino Nano ESP32, not for other ESP32 based boards.
For best results you need to shift the voltage, either using level shifter modules like @robtillaart suggested above or if you don't have those on hands, place a simple resistive voltage divider (e.g., a 1 kΩ and a 2 kΩ resistor) on the DT line to step the 5V signal down to ~3.3V before it enters the ESP32.
You can also power HX711 at 3.3V, but you would not get as stable readings that way. You can test it though.
Yes, but it can have side effects. There is a section about this in the readme.md you need to read. It also points to an HX711 library that is explicitly written to read multiple loadcells in parallel.
(Somewhere on my "bucket-list" is to write an HX711 library that uses an MCP23S17 to read 16 loadcells in parallel, think 4x4 5x3 or 8x2 matrix)
Just DT line.
SCK is from esp to hx, voltage divider would just bother there.
Sparkfun is your best option, if you still need to buy the board.
But DT level shifting is so simple that don't complicate your life if Sparkfun is not easily available. If you don't need high speed, you can go at 3.3V as well and average output on your code.
Thank you.
EmilyJane also suggested the SparkFun one.
I'll consider them both, price will probably be the deciding factor if everything else is equivalent.
Thank you for suggesting this.
robtillaart also suggested the Adafruit one.
I'll consider them both and ,if the technical specs are mostly the same, price will be the deciding factor.
Just finished testing a 5 kg load cell I removed from a kitchen scale that I accidentally left on top of the toaster oven and melted the case.
I used a SEEED XIAO ESP32-C5, Sparkfun HX711 module, and Rob's HX711 library to calibrate. The HX711 was powered from VUSB -> VCC and 3V3 -> VDD from the XIAO. Everything worked perfectly.
That's great to know.
I'm leaning towards the SparkFun too but I have to look around a bit more, because were I'm from they cost 12€ each + shipping.
To put it in 80Hz you just have to jump the Rate pads in the back, correct?
