This page gives an overview of SCU Watchdog BareMetal driver

Introduction

The watchdog timer can be used to prevent system lockup; for example, when software becomes trapped in a deadlock.
In normal operation, the user restarts the watchdog at regular intervals before the timer counts down to zero.
In cases where the timer does reach zero and the watchdog is enabled, one or a combination of the following signals is

generated: a system reset, an interrupt, or an external signal. The watchdog timeout period and the duration of any output signals are programmable.

For more information, please refer Chapter 14: Timers and clocks in Zynqmp Trmwhich includes links to the official documentation and resource utilization.

Driver Sources

The source code for the driver is included with the Vitis Unified Software Platform installation, as well as being available in the Xilinx Github repository.

Driver Name	Path in Vitis	Path in GitHub
scuwdt	<Vitis Install Directory>/data/embedded/XilinxProcessorIPLib/drivers/scuwdt	https://github.com/Xilinx/embeddedsw/tree/master/XilinxProcessorIPLib/drivers/scuwdt

Note: To view the sources for a particular release, use the rel-version tag in github. For example, for the 2020.1 release, the proper version of the code is: https://github.com/Xilinx/embeddedsw/tree/master/XilinxProcessorIPLib/drivers/scuwdt

The driver source code is organized into different folders. The table below shows the scuwdt driver source organization.

Directory	Description
src	Driver source files, make and cmakelists file
examples	Example applications that show how to use the driver features
doc	Provides the API and data structure details
data	Driver .tcl , .mdd and .yaml files

Note: The .yaml(in data folder) and CMakeLists.txt(in src folder) files would be used in System Device Tree based flow.

Driver Implementation

For a full list of features supported by this IP, please refer Chapter 14: Timers and clocks in Zynqmp Trm

Features

Controller/Driver features supported

32-bit counter that generates an interrupt when it reaches zero
8-bit prescaler to enable better control of the interrupt period
Configurable single-shot or auto-reload modes
Configurable starting values for the counter
can be used in watchdog mode or timer mode

Known issues and Limitations

None

Example Applications

Refer to the driver examples directory for various example applications that exercise the different features of the driver. Each application is linked in the table below. The following sections describe the usage and expected output of the various applications. These example applications can be imported into the Vitis IDE from the Board Support Package settings tab.

Links to Examples

Examples Path:

https://github.com/Xilinx/embeddedsw/tree/master/XilinxProcessorIPLib/drivers/scuwdt/examples

Test Name	Example source	Description
Polled	xscuwdt_polled_example.c	This example tests the functioning of the Scu Private WDT driver and hardware in Timer mode using polled mode.
Interrupt	xscuwdt_intr_example.c	This example tests the functioning of the Scu Private WDT driver and hardware in Timer mode using interrupt mode.

Example Application Usage

SCUWDT examples

Expected Output

Polled mode example

https://github.com/Xilinx/embeddedsw/blob/master/XilinxProcessorIPLib/drivers/scuwdt/examples/xscuwdt_polled_example.c

This test contains a design example using the Xilinx SCU Private Watchdog Timer driver (XScuWdt) and hardware device in watchdog mode. It
illustrates how to initialize the watchdog device and restart it periodially in polling mode to avoid the assertion of the WDRESETREQ pin.

Output

SCU WDT Polled Mode Example Test
Successfully ran SCU WDT Polled Mode Example Test

Interrupt mode example

https://github.com/Xilinx/embeddedsw/blob/master/XilinxProcessorIPLib/drivers/scuwdt/examples/xscuwdt_intr_example.c

This file contains a design example using the Xilinx SCU Private Watchdog Timer driver (XScuWdt) and hardware in Timer mode using interrupts. It illustrates
how to use Watchdog device in the timer mode.

Output

SCU WDT Interrupt Example Test
Successfully ran SCU WDT Interrupt Example Test

Example Design Architecture

NA

Changelog

2024.1

None

2023.2

https://github.com/Xilinx/embeddedsw/blob/xlnx_rel_v2023.2/doc/ChangeLog#L299

2023.1

None

2022.2

None

2022.1

None

2021.2

None

2021.1

https://github.com/Xilinx/embeddedsw/blob/xlnx_rel_v2021.1/doc/ChangeLog#L388

2020.2

https://github.com/Xilinx/embeddedsw/blob/release-2020.2/doc/ChangeLog#L667

2020.1

https://github.com/Xilinx/embeddedsw/blob/release-2020.1/doc/ChangeLog#L524

2019.2

None

2019.1

None

Xilinx Wiki

SCU Watchdog Standalone driver

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