Remote Processing RPC-210 - Manual (Page 42)

EXTERNAL INTERRUPTS SECTION 9
Page 9-2
Line 10 sets up the operating system to process interrupt
0. Lines 20 and 30 increm ent a counter used by the
interrupt subroutine. W hen INT 0 goes low, code
starting at line 500 is executed as soon as the current
RPBASIC-52 statement is finished (usually in 1 mSec).
RETI is necessary to allow other interrupts. However,
if INT 0 remains low, the interrupt program will be re-
executed sta rting at line 50 0 as soon as R ETI is
executed. To pr event this, try to reset the cause of the
interr upt. If this is not possible, then execute
550 ONITR 0
This will disable INT0. Y ou can monitor this line by
tying it to a free input at J3 and use ON LIN E to detect
when it is high again.
Interrupt Priority
I N T 0 i s s e co n d o n ly to O N T IC K I f a n ON T I C K
progr am is exec uting, an ON ITR r outine is delayed until
ONT ICK is finished. ONIT R cannot be interrupt by any
other multi-tasking routine such as ON COM$, ON
LINE, etc.
APPLICATION PROGRAMS
Interrupts are part of the CP U process. For setup
example, review any of the programs below.
F i le n am e Description
COUNT1.BAS Quadrature encoder input. Counter
program generates INT 0 on 0
crossing.
COUNT2.BAS Quadrature encoder input. Counter
program generates INT 0 when
preload count matches current
count.
COUNT3.BAS Pulse input. Interrupt when count
goes through 0.
RTC-5.BAS Interrupt at preset hour, m inute,
and/or second.