@jtbylsma Correct. What is your load cell’s rated excitation voltage ? In case , it’s more than 3.3V, try to bend the 3.3V shield pin and connect it to Arduino’s 5V and remove the analogReference(EXTERNAL) so that the analog reference would be 5V. This way, your load cell would be excited with 5V instead of 3.3V. The potentiometer is intended to set the amplifier’s reference voltage. It is used to offset the output signal to mid-supply in case you are planning to measure the weight in two direction on the load cell. If you are planning to measure weight in only one direction, you can set it to have an output RAW value of near the minimum (~0).
Ahhhhh…looks like that could be the problem. The excitation voltage of my load cell is 10-15V. I’m guessing increasing the reference voltage to 5V would still help? Instead of bending the pin and connecting it to the Arduino’s 5V pin, could I just connect a jumper between 5V on the shield and AREF on the shield? If not, I’ll try your method.
This won’t work because the load cell will still be 3.3V excited. The load cell excitation pins on the shield of both Strain 1 and Strain 2 are connected to the 3.3V line which is connected to the Arduino 3.3V pin when the shield is stacked. If you want to power your load cell at 5V, the 3.3V pin of the shield will have to be disconnected from the 3.3V pin on the Arduino and connected to 5V instead. Bending the shield’s 3.3V pin and disconnected it from the Arduino is a “hack” to power your load cell at 5V.
You can find the Load Cell Shield Arduino library and examples in this github repository :
1 Like
Thank you for the link. Now I have connected my amplifier board to Arduino and 2 load cells. When I try to load the program I get this error:
Arduino: 1.8.9 (Windows 7), Board: “Arduino/Genuino Uno”
libraries\Wheatstone_Bridge_Interface_to_Serial\WheatstoneBridge.cpp.o (symbol from plugin): In function `WheatstoneBridge::WheatstoneBridge(unsigned char, int, int, int, int)’:
(.text+0x0): multiple definition of `WheatstoneBridge::WheatstoneBridge(unsigned char, int, int, int, int)’
sketch\WheatstoneBridge.cpp.o (symbol from plugin):(.text+0x0): first defined here
libraries\Wheatstone_Bridge_Interface_to_Serial\WheatstoneBridge.cpp.o (symbol from plugin): In function `WheatstoneBridge::WheatstoneBridge(unsigned char, int, int, int, int)’:
(.text+0x0): multiple definition of `WheatstoneBridge::WheatstoneBridge(unsigned char, int, int, int, int)’
sketch\WheatstoneBridge.cpp.o (symbol from plugin):(.text+0x0): first defined here
libraries\Wheatstone_Bridge_Interface_to_Serial\WheatstoneBridge.cpp.o (symbol from plugin): In function `WheatstoneBridge::WheatstoneBridge(unsigned char, int, int, int, int)’:
(.text+0x0): multiple definition of `WheatstoneBridge::~WheatstoneBridge()’
sketch\WheatstoneBridge.cpp.o (symbol from plugin):(.text+0x0): first defined here
libraries\Wheatstone_Bridge_Interface_to_Serial\WheatstoneBridge.cpp.o (symbol from plugin): In function `WheatstoneBridge::WheatstoneBridge(unsigned char, int, int, int, int)’:
(.text+0x0): multiple definition of `WheatstoneBridge::~WheatstoneBridge()’
sketch\WheatstoneBridge.cpp.o (symbol from plugin):(.text+0x0): first defined here
libraries\Wheatstone_Bridge_Interface_to_Serial\WheatstoneBridge.cpp.o (symbol from plugin): In function `WheatstoneBridge::WheatstoneBridge(unsigned char, int, int, int, int)’:
(.text+0x0): multiple definition of `WheatstoneBridge::measureForce()’
sketch\WheatstoneBridge.cpp.o (symbol from plugin):(.text+0x0): first defined here
libraries\Wheatstone_Bridge_Interface_to_Serial\WheatstoneBridge.cpp.o (symbol from plugin): In function `WheatstoneBridge::WheatstoneBridge(unsigned char, int, int, int, int)’:
(.text+0x0): multiple definition of `WheatstoneBridge::getLastForce()’
sketch\WheatstoneBridge.cpp.o (symbol from plugin):(.text+0x0): first defined here
libraries\Wheatstone_Bridge_Interface_to_Serial\WheatstoneBridge.cpp.o (symbol from plugin): In function `WheatstoneBridge::WheatstoneBridge(unsigned char, int, int, int, int)’:
(.text+0x0): multiple definition of `WheatstoneBridge::getLastForceRawADC()’
sketch\WheatstoneBridge.cpp.o (symbol from plugin):(.text+0x0): first defined here
libraries\Wheatstone_Bridge_Interface_to_Serial\WheatstoneBridge.cpp.o (symbol from plugin): In function `WheatstoneBridge::WheatstoneBridge(unsigned char, int, int, int, int)’:
(.text+0x0): multiple definition of `WheatstoneBridge::linearCalibration(int, int, int, int)’
sketch\WheatstoneBridge.cpp.o (symbol from plugin):(.text+0x0): first defined here
collect2.exe: error: ld returned 1 exit status
exit status 1
Error compiling for board Arduino/Genuino Uno.
Could you please help? My load cells are 5 kg.
@matiussummer Please make sure that you have correctly installed the library. Please follow these instructions.
Hello,
I have two questions regarding the decoupling capacitor for the arduino to enhance the measurement results.
- What capacity would you recomend?
- Between which pins do I use the Capacitor? Between the AREF & 3,3V or AREF & GND?
Thank you for your help
If you are planning to use external analog voltage reference by connecting the 3.3V pin to AREF, we recommend connecting an external 100nF capacitor between AREF and GND. Also, please don’t forget to use the function analogReference(EXTERNAL) as explained here
Great! Thank you for your quick response 
hello,
I am trying to connect the amplifier to an Arduino NANO, but I cannot get it to work.
I connected the strain1 to A0, strain2 to A1, and then Vin, GND and 5V to the respective connectors, but it is not working like it says it should according to the test procedure (PDF file). Do you have any ideas on what I may be doing wrong?
Pablo
Please connect 3.3V from the Arduino Nano to the 3.3V pin of the load cell shield as the circuitry on the load cell shield (and the load cell excitation pin) is powered through the 3.3V pin. You can also power the shield with 5V by connecting 5V output from Arduino Nano to the 3.3V pin of the load cell shield. In this case, the load cells connected on the shield will be 5V excited (instead of 3.3V).
Thank you for the quick response! That worked perfectly.
One more question, I am trying to connect a half-bridge strain gauge to the shield, but I am not sure which pins to connect it to. Could you help me with it? Thanks again.
Pablo
hello,
I am trying to connect the shield to a quarter bridge strain gauge but when I apply the voltage, the current is too high (and has burned the arduino). I checked the wiring a few times and I think it is properly set (with 3 dummy resistances and the load resistance). Is there something I may be missing?
- What is the resistance values of the resistors and the strain gauge ?
- How was your bridge powered ?
- Could you provide a wiring diagram of your bridge ?
I tried two different setups (shown in the pictures); the strain gauges have a nominal value of 1k.
I think there was a mismatch between the shield datasheet and the webpage of strain gauges configuration given at the site. I checked with different tests and got it to kinda work.
Now, I can get the shield to output either 0V, 3V, or somewhere approximately in the middle (i.e. 1.4 V) but it does not show the change in voltage.
I tried using another amplifier box and I did get a signal but with the shield I am not getting any feedback signal (not even a small one).
SG wire setup.pdf (621.0 KB)
The gain of the AD8426 instrumentation amplifier IC is set to 495 by default on the shield with the gain resistor Rgain = 100 Ohms. A voltage input from the wheatstone bridge of 1.4V or 3V will saturate the output of the amplifier. You probably need to remove the gain resistor for your application (Gain 1 or Gain 2 depending on the channel you are using). When no gain resistor is used, the gain of the AD8426 would be 1 and gain error and drift are minimal. Please note that the gain resistors are smd components, therefor, some smd soldering skills might be needed.
Hello, everybody,
I have been working on a load readout device using load cell 0-300kg with an excitation of 10V and an output of 2mV/V. I have searched the internet and have found 2 ways of doing it first with HX711 amplifier second with load cell shield or nanoshield (company from Brazil make them). Do you know what would be the difference between them two? Which one give me more stable more accurate readout?
Thanks
Hi,
The HX711 Load Cell Amplifier is a single channel amplifier with a digital interface output and provides a 24 bit resolution which is higher than the Arduino’s 12 bit. However, the data output rate only goes to a maximum of 80Hz. The Load Cell / Wheatstone Amplifier Shield is a 2 channel analog output amplifier with a default of 100Hz filter (that can be removed for faster data output rate), therefore, it would be only limited by the ADC sampling rate of the Arduino board that can theoretically be 9600Hz. Also, it’s important to note that the Shield allow a maximum excitation voltage of 5V.
Hello,
I ve read that the shield has two channel so that 2 load cells can be used. I would like to ask :
- Is it possible to get measurements for these 2 channels simultaneously in real time applications?
- Are the gains of each channel independent of each other?
- Is this shield possible to be mounted in NUCLEO-F334R8 microcontroller and in which way ?
https://www.st.com/en/evaluation-tools/nucleo-f334r8.html
(It is a ST microcontroller with both Arduino uno v3 connectors and ST connectors)
Thanks
Giannis