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23.0 Watchdog [T-Series Datasheet]

Overview

The Watchdog system can perform various actions if the T-Series device does not receive any communication within a specified timeout period.

A typical usage is to first use the IO Config system to set the power-up defaults for everything as desired, and then configure the watchdog to reset the device on timeout.  For example, consider a software program that enables the watchdog to reset the T-Series device with a 60 second timeout, and then the software has a loop that talks to the device once per second.  If something goes wrong with the software, or some other problem that causes communication to stop, the T-Series device will reset every 60 seconds until communication resumes.

The watchdog timeout can be set as low as 1 second, but such a low value is usually not a good idea.  For example, when a USB device resets it takes a little time for USB to re-enumerate and software to be able to talk to the device again, so you could get in a situation where the device keeps resetting so often that you can't start talking to it again.  This might require using the reset-to-factory jumper—see 11.0 SPC for details.

The timeout period is reset when a response to a command-response packet is sent to the host. Alternatively, "strict" mode can be enabled. When strict mode is enabled the timeout period is reset by writing the key value to WATCHDOG_STRICT_CLEAR. The key can be set by writing WATCHDOG_STRICT_KEY_DEFAULT. While strict is disabled writing any value to WATCHDOG_STRICT_CLEAR will clear the watchdog. Note that writing to WATCHDOG_STRICT_CLEAR will clear the watchdog when the write is processed, not when a response packet is sent.

Normal spontaneous stream data does not reset the watchdog timeout.  The timeout period is reset when a response to a command-response packet is sent to the host, so if streaming you must do some periodic command-response communication to reset the watchdog timeout.

Register Listing

Use the following registers to configure the watchdog system:

Watchdog Registers
Name Start Address Type Access
WATCHDOG_ENABLE_DEFAULT 61600 UINT32 R/W    
WATCHDOG_ADVANCED_DEFAULT 61602 UINT32 R/W    
WATCHDOG_TIMEOUT_S_DEFAULT 61604 UINT32 R/W    
WATCHDOG_STARTUP_DELAY_S_DEFAULT 61606 UINT32 R/W    
WATCHDOG_STRICT_ENABLE_DEFAULT 61610 UINT32 R/W    
WATCHDOG_STRICT_KEY_DEFAULT 61612 UINT32 R/W    
WATCHDOG_STRICT_CLEAR 61614 UINT32 W    
WATCHDOG_RESET_ENABLE_DEFAULT 61620 UINT32 R/W    
WATCHDOG_DIO_ENABLE_DEFAULT 61630 UINT32 R/W    
WATCHDOG_DIO_STATE_DEFAULT 61632 UINT32 R/W    
WATCHDOG_DIO_DIRECTION_DEFAULT 61634 UINT32 R/W    
WATCHDOG_DIO_INHIBIT_DEFAULT 61636 UINT32 R/W    
WATCHDOG_DAC0_ENABLE_DEFAULT 61640 UINT32 R/W    
WATCHDOG_DAC0_DEFAULT 61642 FLOAT32 R/W    
WATCHDOG_DAC1_ENABLE_DEFAULT 61650 UINT32 R/W    
WATCHDOG_DAC1_DEFAULT 61652 FLOAT32 R/W    

Example

The most common way to use Watchdog is to write:

WATCHDOG_ENABLE_DEFAULT=0
WATCHDOG_TIMEOUT_S_DEFAULT=60
WATCHDOG_RESET_ENABLE_DEFAULT=1
WATCHDOG_ENABLE_DEFAULT=1

If the device does not receive any communication for 60 seconds, the watchdog will cause the device to reset.  So if nothing is talking to the device, it will reset every 60 seconds.  In conjunction, you would often use the IO Config system to configure the power-up defaults as desired. 

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