Jump to main content

# 1.38 WDT Timeout

This example application shows how to generate a Watchdog timer reset by emulating a deadlock.

## Description

This example application shows how the WDT peripheral library resets the watchdog timer by not feeding the watchdog on switch press. The application sets up the watchdog to reset the device. The application sets up the timer to blink an LED to emulate a process. A user switch press forces the device to wait in an infinite loop to emulate a deadlock. As a result a device reset is triggered as the watchdog counter overflows the bounded value.

## 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 be downloaded using content manager by following these instructions.

Path of the application within the repository is apps/wdt/wdt_timeout/firmware.

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

Project Name | Description
--- | ---
sam_9x75_curiosity.X | MPLABX project for SAM9X75 Curiosity Development Board
sam_9x75_curiosity_pro.X | MPLABX project for SAM9X75 Curiosity Pro Development Board

## Setting Up AT91Bootstrap Loader

To load the application binary onto the target device, the user needs to use at91bootstrap loader. Refer to the at91bootstrap loader documentation for details on how to configure, build and run bootstrap loader project and use it to bootstrap the application binaries.

## Setting Up the Hardware

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

Project Name | Description
--- | ---
sam_9x75_curiosity.X | SAM9X75 Curiosity Development Board
sam_9x75_curiosity_pro.X | SAM9X75 Curiosity Pro Development Board

### Setting Up SAM9X75 Curiosity Development Board

Additional hardware required:

- SD card with FAT32 file system

Setting up the SD card:

- Download harmony MPU bootstrap loader
- Copy the downloaded boot loader binary( boot.bin) onto the SD card

Setting up the board:

- SDMMC slot used for bootloading the application is SD BOOT (J14)
- Connect the UART DEBUG J35 on board to the computer using a UART-FTDI cable (to enable debug com port)
- Connect the USB port J2 on board to the computer using a micro USB cable (to power the board)

### Setting Up SAM9X75 Curiosity Pro Development Board

Additional hardware required:

- SD card with FAT32 file system

Setting up the SD card:

- Download harmony MPU bootstrap loader
- Copy the downloaded boot loader binary( boot.bin) onto the SD card

Setting up the board:

- SDMMC slot used for bootloading the application is microSD (J42)
- Connect the UART DEBUG J63 on board to the computer using a UART-FTDI cable (to enable debug com port)
- Connect the port J1 on board to the computer using a Type-C USB cable (to power the board)

## Running the Application

1. Build the application using its IDE.
2. Copy the output binary (named harmony.bin) onto the SD Card (Refer to the Setting up hardware section above for setting up the SD card).
3. Insert the SD card into SDMMC slot on the board (Refer to the Setting up hardware section for the correct SDMMC slot).
4. Open the Terminal application (Ex.:Tera term) on the computer.
5. Connect to the (USB to Serial) COM port and configure the serial settings as follows:
   - Baud: 115200
   - Data: 8 Bits
   - Parity: None
   - Stop: 1 Bit
   - Flow Control: None
6. Reset the board to run the application.
7. LED blinks in green color and the console displays the following message.
8. Press the switch to put the system in a deadlock.
9. LED toggles in blue color and console displays the following message.
10. WDT will reset the device in four seconds and the demonstration should restart.

Following table provides details of Switch and LED names:

Board | Switch Name | LED Name
--- | --- | ---
SAM9X75 Curiosity Development Board | USER | RGB_LED(Green, Blue)
SAM9X75 Curiosity Pro Development Board | USER | RGB_LED(Green, Blue)

Rev: E