Hello, I have two load cells connected to a load cell shield as shown in the example using Strain 1 and Strain 2. I would like to have them displayed separately on an LCD screen in this case 16x2 LCD Shield Kit for Arduino and have the buttons work as I would like. The example I have seen shows pin A0 bent outwards and connected to A5 on top of the LCD shield. Would this still suffice? Any ideas? Thanks
@Shem This depends on the LCD Shield you are using. In this example, we used this LCD Shield which uses the pin A0 of the Arduino board for the buttons. And since the Load Cell Shield also uses the A0 pin for Strain 1, we had to bend the A0 pin of the LCD Shield and connect it to A5. Otherwise, we would have conflicting analog pins. You can take a look at the schematic of the LCD Shield you are using to know which pins it uses and confirm if A0 and A1 are not being used. If so, you can use the same trick and connect the used A0 and/or A1 pins from the LCD to other analog pins (A2,A3,A4 and A5)
@Shem This depends on the LCD Shield you are using. In this example, we used this LCD Shield which uses the pin A0 of the Arduino board for the buttons. And since the Load Cell Shield also uses the A0 pin for Strain 1, we had to bend the A0 pin of the LCD Shield and connect it to A5. Otherwise, we would have conflicting analog pins. You can take a look at the schematic of the LCD Shield you are using to know which pins it uses and confirm if A0 and A1 are not being used. If so, you can use the same trick and connect the used A0 and/or A1 pins from the LCD to other analog pins (A2,A3,A4 and A5)
@Brahim i am using load cell, arduino and hx711 for measuring dynamic load with frequency upto 10hz and getting the data with the help of serial monitor. can you tell me at what frequency the data is being shown on the serial monitor?
I’m trying to connect a 50 kg (~110 lb) S-type load cell to an Arduino. Everything is connected and working; however, I can’t get a force reading above ~22 kg, which equates to a strain reading of around 675. Any ideas why I’m not getting the full range of the load cell? Is there anything I can do with this shield to give me the full range? Thanks for the help!
How are you powering the load cell shield (3.3V or 5V) ? If it is directly stacked on your Arduino board, this means that the shield is powered with the 3.3V. In this case, you will need to connect 3.3V Arduino pin to AREF and use the analogReference(EXTERNAL) function in your code.
Yes, I stacked it directly on the Arduino board. To connect the 3.3 V Arduino pin to AREF, do I just place a jumper from the 3.3V pin on the shield to the AREF pin on the shield while it’s stacked? I did that and added the analogReference(EXTERNAL) function in the setup portion of my code, and I’m still not getting the full range. How does the potentiometer on the shield factor in? Should I be adjusting that until my zero load strain value is ~338 as shown in the test procedure?
@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).