I'm trying to get a reading from a set of four 3-wire load cells connected with a Sparkfun Load Cell Combinator (link removed) to a Sparkfun HX711 amplifier.
I've followed the Sparkfun hookup guide (link removed) however I only get readings of 0.0 using the Sparkfun Arduino code.
I'd really appreciate some suggestions where I may be going wrong or things that are worth checking.
I'm using a set of digital bathroom scales from eBay that I checked before disassembling.
The wires from each load cell were very thin and I soldered them to thicker jumper cables to allow easy hookup to the Load Cell Combinator. After soldering I checked the resistance between each wire on each load cell and found that the centre wire is red (Black-White resistance is double any combination with Red wire). Based on this I'm happy that the connections are good.
The pins on the combinator are connected to the colour coded pins on the HX711 (Red-Red, etc.). The resistance between the pins are:
I was surprised by this as I was expecting two smaller values and one larger for each wire (e.g. 2,2,3 not 3,3,2)
The HX711 is connected to the Arduino with the following:
Arduino Pin 2 - HX711 CLK
Arduino Pin 3 - HX711 DAT
Arduino 5V - HX711 VDD (VDD pin soldered to adjacent VCC pin)
Arduino GND - HX711 GND
I've downloaded the HX711 library created by bogde and received no erors when compiling and uploading to the Arduino.
When I run the Sparkfun Calibration code and add a weight I just get 0.0, even with a large range of different calibration factors.
Has anyone encountered this problem before?
Edit: @Andy aka, here are the voltages of the load cell connector pins on the HX711 (Black is connected to ground on the Arduino):
Edit 2 07/12/16:
I've measured the following voltages relative to the E- pin on the Combinator (connected to Black on HX711 which in turn is connected to Arduino GND)
White - Red - Black
UL 2.16 1.44 0.00
UR 2.16 1.44 1.46
LL 2.16 2.88 2.86
LR 2.16 2.88 4.34