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# 1.6 DWT Timeout

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

## Description

This example application configures Programmable secure dual watchdog timer (PS-WDT) to run in window Watchdog mode. Watchdog period is 4 seconds, with 1 second repeat threshold and 3 second level threshold. Two switches are used to simulate deadlock and repeat threshold violation. Blinking LED simulates a normal process. When the application is run, the watchdog is cleared after every 2 seconds.

Pressing switch 1, will emulate a deadlock by not clearing the watchdog. LED will remain turned on. 3 seconds after previous watchdog clear, level interrupt will be generated. 4 second after previous watchdog clear, MCU will be reset.

Pressing Switch 4 will result in a watchdog clear, if the repeat threshold have not elapsed since the previous watchdog clear, this will result in a repeat threshold violation interrupt. Pressing Switch 4 twice in quick succession will result in a guaranteed repeat threshold violation.

## 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/dwdt/dwdt_timeout.

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

Project Name | Description
--- | ---
sam_a7d65_curiosity.X | MPLABX project for SAMA7D65 Curiosity Board
sam_a7d65_curiosity_pro.X | MPLABX project for SAMA7D65 Curiosity Pro Board

## Setting Up AT91Bootstrap Loader

To load the application binary onto the target device, we need 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_a7d65_curiosity.X | SAMA7D65 Curiosity Board
sam_a7d65_curiosity_pro.X | SAMA7D65 Curiosity Pro Board

### Setting Up SAMA7D65 Curiosity 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 SDMMC1 (J10)
- Connect the USBA port J3 on the board to the computer using a Type-C USB cable (to power the board)
- Connect the UART Debug port (J35) on the board to the computer using a FTDI-USB cable

### Setting Up SAMA7D65 Curiosity Pro 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 microUSD (J42)
- Connect the USBA port J1 on the board to the computer using a Type-C USB cable (to power the board)
- Connect the UART Debug port (J63) on the board to the computer using a FTDI-USB cable

## Running the Application

1. Open the Terminal application (Ex.: Tera term) on the computer.
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.
4. Connect to the Virtual COM port and configure the serial settings as follows:
   - Baud: 115200
   - Data: 8 Bits
   - Parity: None
   - Stop: 1 Bit
   - Flow Control: None
5. Build and run the application using its IDE.
6. Console should show the following output and LED1 should be blinking.
7. Press Switch 2 to emulate a deadlock.
8. Console output is updated as follows and LED2 starts blinking:
9. LED2 stops blinking and “RomBOOT” is printed on the console indicating a processor reset.

Refer to the following table for Switch names for different boards:

Board | Switch 1 | LED 1 | LED 2
--- | --- | --- | ---
SAMA7D65 Curiosity Board | SW2 | RGB LED (Blue) | RGB LED (Red)
SAMA7D65 Curiosity Pro Board | SW2 | RGB LED (Blue) | RGB LED (Red)

Rev: C