I'm currently working on a project that uses the HX711 load cell amplifier while connected to a series of strain gauges in a full bridge circuit. I'm using an Arduino Nano and have the CLK of the HX711 connected to pin D5 and the DAT connected to pin D6. Hx711 manufacturer suggest pins D2 and D3 instead however I was under the impression that any digital I/O pins would work as long as the code was changed to signal this. When the calibration code provided by the HX711 manufacturer is uploaded the serial monitor reads constant value of -78kg and will still read this value when the strain gauge circuit is connected. I have re-soldered the connections from arduino to hx711 so suspect that isn't the problem. The connections from Hx711 to strain gauge bridge circuit are female to female jumper wires. If anybody has experienced a similar problem and could help I'd be very grateful!

Link for Hx711 setup with calibration code and Hx711 library: https://learn.sparkfun.com/tutorials/load-cell-amplifier-hx711-breakout-hookup-guide/all

Link to Hx711 schematic: https://cdn.sparkfun.com/datasheets/Sensors/ForceFlex/SparkFun_HX711_Load_Cell_v11.pdf

(https://i.stack.imgur.com/mic2J.jpg) = Serial monitor

(https://i.stack.imgur.com/2Xkb4.jpg) = Calibration code used

(https://i.stack.imgur.com/btzID.png) = Full circuit diagram

(https://i.stack.imgur.com/mio7e.png) = Load cell wiring, colours correspond to those coming out HX711 in full circuit diagram

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    \$\begingroup\$ Please provide a link to the datasheet for the load cell amplifier, and also a link to where you obtained HX711.h. Finally, please use the built-in schematic editor to draw your circuit, including the connections to the Arduino, the HX711 and the load cell. \$\endgroup\$ – Elliot Alderson Mar 12 '19 at 14:21
  • \$\begingroup\$ You are missing a connection to VDD on the load cell amplifier board. \$\endgroup\$ – Elliot Alderson Mar 12 '19 at 14:50
  • \$\begingroup\$ I can't believe I missed this! Thank you so much, I'll solder this later and confirm if it fixes the problem tomorrow \$\endgroup\$ – Fergus Gunn Mar 12 '19 at 15:20

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