top of page

Digital to Analog Converter

Objective 

To ensure that the digital to analog converter can output 4 different voltages.

Proof of Concept 

Use the DAC code that we wrote and run the code while inputting 4 voltage values. Measure the 4 different voltage values by switching which pin you are measuring. 
Known Parameters: Output Voltage = (Reference Voltage / Resolution) x Digital Value
Pass criteria: Measured Output Voltage is within +/- 10mV of the Calculated Output Voltage
Fail criteria: Measured Output Voltage is greater than or less than 10mV of the Calculated Output Voltage

Methods

Need to ensure that the DAC can  sufficiently output a given voltage. Using the DAC code that we wrote, run the code and it will display a message asking for an output voltage. The user will insert the voltage value that they want and each pin will output that voltage. We got the output voltage by taking the reference voltage divided by the resolution then multiplying it by the digital value. The reference voltage is the 5 V that we are inputting from the Raspberry Pi, the resolution is 4096 and the digital value is the fraction of what you want the output to be. The code that we use will automatically compute that equation for you with the output that the user will input. Measure each of the outputs to make sure that each pin displays the same output that the user imputed on the Raspberry Pi. 

Results 

Our ideal output voltage would be the exact value we calculated. We got the output voltage by taking the reference voltage divided by the resolution then multiplying it by the digital value. Due to the calculations and rounding with the code, we set our passing values to be within 10mV of the calculated value. After observing our results, we found that all of the given inputs would successfully be outputted to the correct output pin.

DAC Calculated Voltages and Measured Voltages

Output Pin
Calculated Output Voltage
Measured Output Voltage

DAC Test 1

Output Pin
Calculated Output Voltage
Measured Output Voltage
VA
2.61
2.60
VB
4.17
4.19
VC
5.21
5.21
VD
0.00
0.00

DAC Test 2

DAC Code 

DAC Code test 1.PNG

DAC Test Code

IMG_0340.jpg

Images

DAC Set Up 

DAC Set Up

bottom of page