Poll Watchdog Interrupt

Polls the watchdog interrupt of the Q8 data acquisition system.

Library

qctools

Description

The Poll Watchdog Interrupt block for the Q8 series of I/O cards provides a mechanism for polling the watchdog interrupt of the card. It reads the Interrupt Status Register of the Q8 card. The output goes high when the watchdog interrupt occurs. The block has an option for resetting the interrupt flag after an interrupt occurs. The block polls the Interrupt Status Register each sampling instant. The Poll Interrupts series of blocks may be used in Windows regardless of the status of the Q8 Windows driver.

Block Outputs

WATCHDOG

The output goes high when the watchdog counter output goes low. The output is edge-triggered. The falling edge is used because the external WATCHDOG pin is held high when the watchdog output is disabled. Hence, a falling edge is the most natural transition on which to interrupt the CPU.

Parameters and Dialog Box

Board Number

The board number of the I/O card. If there is only one Q8 board in your system, then the board number should be zero. The second Q8 board in your system is board number 1, etc.

Sample Time

A sample time must be specified for all discrete blocks. The default value extracts the sample time from the RTW Options dialog, under Solver/Fixed step size. A numeric value rather than 'auto' should be specified in this dialog field for this default to make sense.

Clear Flag After Polling

When this option is checked, the block clears the polled bit of the Interrupt Status Register after reading it. This option allows the flag to be repeatedly polled. The output will remain high for one sampling instant when this option is checked. Otherwise, the output stays high once it has gone high.