Hello,
I am working with an Arduino 101 and connected it to a wheastone bridge with 3 resistors (330 ohms) and 1 strain gauge. I have given an input voltage of 5V to the bridge, I measured the output voltage on a multimeter and through the Arduino and there seems to be a large difference in these values. When I change the input voltage to 3.3 V, the voltage measured form the multimeter and Arduino are equal. Could anyone please explain why this is happening?
Thank you
Circuit?, actual measurements? Strain gauge datasheet?
I'm sorry about the hand drawn circuit.
Values when input voltage is 5V:
Voltage between point 8 and GND on multimeter = 2.43V
Voltage between point 8 and GND on Arduino = 3.69V
Voltage between point 7 and GND on multimeter = 2.51V
Voltage between point 7 and GND on Arduino = 3.80V
Voltage between points 7 and 8 on multimeter = 86.2 mV
Values when input voltage is 3.3V:
Voltage between point 8 and GND on multimeter = 1.59V
Voltage between point 8 and GND on Arduino = 1.60V
Voltage between point 7 and GND on multimeter = 1.64V
Voltage between point 7 and GND on Arduino = 1.65V
Voltage between points 7 and 8 on multimeter = 55.5 mV
These are the specifications (attached) I could find regarding the strain gauges on the website:
Mini DC-DC 12-24V To 5V 3A Step Down Power Supply Module Voltage Buck Converter Adjustable Efficiency 97.5%
Input Voltage:DC 4.5-24V
Output Voltage:integration adjustable and fixed output,back side can choose fiexd output voltage
Adjustable Range:0.8-17V,fixed voltage (1.8V 2.5V 3.3V 5V 9V 12V)
Output Current:3A (max),actual testing input 12V output 1.5A
What does your code assume is the reference voltage for the ADC? I believe it's fixed at 3.3V for the 101. Your results look like what you'd get if you assume it changes to 5V because your circuit is run from 5V.
Steve
Looks like it is set to 3.3V. Thank you for the help!
