1.5 ADC Window Sleepwalking
This application shows how to configure ADC in a sleepwalking operation, where input voltage is measured at a fixed interval, but device is not woken from sleep until the measured value is below a given threshold.
Description
This example application shows how to use the ADC Peripheral library to perform sleepwalking. The ADC peripheral is configured to operate in window mode. The ADC conversion is triggered by RTC compare 0 event. On every trigger, window detection operation is performed in standby sleep. The window interrupt is generated when the input voltage falls below the window upper threshold and the CPU is woken up by this interrupt. ADC window upper threshold is configured as 1/4 th of the reference voltage.
| Board | ADC Window Upper Threshold |
|---|---|
| SAMC21N Xplained Pro Evaluation Kit | 0.825 V |
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_window_sleepwalking/firmware.
To build the application, refer to the following table and open the project using its IDE.
| Project Name | Description |
|---|---|
| sam_c21n_xpro.X | MPLABX project for SAMC21N Xplained Pro Evaluation Kit |
Setting Up the Hardware
The following table shows the target hardware for the application projects.
| Project Name | Description |
|---|---|
| sam_c21n_xpro.X | SAMC21N Xplained Pro Evaluation Kit |
Setting Up SAMC21N Xplained Pro Evaluation Kit
- Connect a voltage below the selected ADC reference voltage (VDDANA) to pin 4 (PB08 – ADC0_AIN2) of the EXT1 connector
- Connect the Debug USB port on the board to the computer using a micro USB cable
Running the Application
- Open the Terminal application (Ex.:Tera term) on the computer
- 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
- Build and Program the application using its IDE
- Console displays ADC Window Detected when ADC input is lower than 1/4 th of the
reference voltage (i.e.: below 0.825V):
