Table of Contents
Advertisement
Functions of the board
8.6
Watchdog/timer
8.6.1 Timer1/Digital watchdog
The 12-bit Timer1 is a downwards counter, which can generate an interrupt after
the reload value has run down (timeout). With the timer, a time base is made
available, independently from the system clock, with which e.g. operations can be
synchronised.
The status of the counter value as well as the status register and interrupt register
can be reread by the software.
Timer1 can be programmed as watchdog, which resets the digital outputs after
the run down of its reload value (timeout).
When releasing watchdog, with each setting of the digital outputs, the reload
value is loaded newly (triggering). The triggering can be done also directly by
software command without the new setting of the digital outputs.
The operation states can be reread. Three different clock signals can be used as
time bases for the watchdog.
8.6.2 Timer2
The 12-bit Timer1 is a downwards counter, that can generate an interupt after the
run down of the reload value (timeout). With the timer, independently from the
PC clock and time base is provided, with which e.g. operations can be
synchronized.
The status of the counter value as well as status and interrupt register can be
reread with the software.
8.7
Counter
On the board PC104-PLSU1500 there is 1 x 16-bit counter input, whose function
can be compared with the counter component 82C54. The counter can be
programmed over software.
The signal input (clock) of the counter is channel 0. Channel 0 is available as
usual digital input, independent from the counter function. The limit frequency is
100 KHz. A signal input for gate and trigger function is not available.
Characteristics of the counter:
2 counting modes: The counter is programmed as upwards counter (see a) or
-
downwards counter (see b)
After reaching the reload value or if the counter has run off, an interrupt can be
-
generated.
Reload value, 16-bit
-
36
PC104-PLUS1500
Advertisement
Table of Contents
