1.3 ADC Sample

This example application shows how to sample an analog input using the ADC and displays the converted samples on a serial terminal.

Description

In this application, DAC output is fed to an analog input for the ADC conversion. An analog input is converted by a software trigger and the converted value is displayed on the console. DAC output is changed by 0.1V upon switch press.
BoardDAC Output Range
SAM D20 Xplained Pro Evaluation Kit0V to 1.65V

Downloading and Building the Application

To clone or download this application from Github, go to the main page of this repository and then click Clone button to clone this repository or download as zip file. This content can also be downloaded using content manager by following these instructions.

Path of the application within the repository is apps/adc/adc_sample/firmware.

To build the application, refer to the following table and open the project using its IDE.

Project NameDescription
sam_d20_xpro.XMPLABX project for SAM D20 Xplained Pro Evaluation Kit

Setting Up the Hardware

The following table shows the target hardware for the application projects.

Project NameDescription
sam_d20_xpro.XSAM D20 Xplained Pro Evaluation Kit

Setting Up SAM D20 Xplained Pro Evaluation Kit

  • Analog input (AIN18) of the ADC is fed from the DAC output
    • Analog input (AIN18) is mapped to pin PA10 which is routed to “Pin 3 of the EXT2 header”
    • DAC output “DAC” is mapped to Port Pin “PA02” and is routed to “Pin 3 of the EXT3 header”
    • Use a jumper wires to connect “Pin 3 of the EXT2 header” to “Pin 3 of the EXT3 header”
  • Connect the Debug USB port on the board to the computer using a micro USB cable

Running the Application

  1. Open the Terminal application (Ex.:Tera term) on the computer
  2. Connect to the EDBG Virtual COM port and configure the serial settings as follows:
    • Baud : 115200
    • Data : 8 Bits
    • Parity : None
    • Stop : 1 Bit
    • Flow Control : None
  3. Build and Program the application using its IDE
  4. Press switch to change the DAC value
  5. ADC input voltage changes by 0.1V when the switch is pressed, from 0.0V to 1.65V
  6. Refer to the table below for the Switch details:
    BoardSwitch Name
    SAM D20 Xplained Pro Evaluation KitSW0
  7. Console displays the ADC count and the ADC input voltage in the console as shown below: