Pepper Computer Modular Computers RS485 - Manual (Page 76)

SMART I/O User’s Manual
March 12, 1996 ©1996 PEP Modular Computers GmbH Page 2 - 36
Chapter 2 SMART-BASE
O_PRELOAD
: With this call the counter preload register can be
set. The syntax is as follows :
<RetVar> := OPERATE(<iovar>, O_PRELOAD, <prevar>);
where the
<iovar>
is typically t_in and
<prevar>
is the value for the preload register
which lies between 1 and 0xFFFFFF.
O_START_CNTDWN
: This function starts the counter counting-down.
When the counter reaches zero, it rolls over to the
maximum value of 0xFFFFFF on the following
clock pulse and starts afresh. The syntax is as
follows :
<RetVar> := OPERATE(<iovar>,O_START_CNTDWN,<prevar>);
where the
<iovar>
is a variable attached to the
Timer I/O (typically t_in) and
<prevar>
may be
one of
OA_PITCLOCK
for selection of the
6 MHz/32 clock input or
OA_TIN
for selection of
t_in inputs.