Remote Processing RPC-210 User Manual
Page 41
EXTERNAL INTERRUPTS
SECTION 9
Page 9-1
Figure 9-1 Interrupt inputs at Connectors
INTRODUCTION
EXTERNAL INTERRUPTS
S E C T IO N 9
External CPU interrupt INT 0 is available for a number
of devices. INT 0 responds to low level signal at either
J7-3, J8-6, or J11-8 by executing code declared by
ONIT R when the curr ent RPBA SIC-52 in struction is
finished. Usually, this is less than 5 mSec.
INT 0
This inter rupt line goe s to J7-3, J8-6, and J11-8. This
line has a 10K pull up. This allows wired OR operation
with other interr upts and expansion boar ds.
INT 0 can be used by the real time clock (J7-1) or
counter (at J11-8). The real time clock allows for wired
OR ope ration. The coun ter does n ot.
WARNING:
COM 1 serial port uses INT 0. If you are using
COM 1, yo u cannot use th is interru pt.
Interrupt 0 is level sensitive. This means that as long as
the line at INT 0 is low, code star ting at the line set in
ONITR will execute if an RETI instruction was given.
If a RETU RN is given, then interrupts stay turned off.
The table below give s the source of interr upts.
Interrupt
0 Source
Description
Wire
OR?
J7-1
Real time clock
Y
J7-5
COM 1 UART
Y
J7-4
Clock square wave
N
J8-6
Expansion port
N / A
J11-7
Counter carry
N
J11-9
Counter Borrow
N
J11-10
Quadrature latch
N
J11-8
Counter port
N / A
INT 0 is available at the following 3 connectors: J7-3,
J8-6, and J11-8.
Programming
The O NIT R com mand is use d to enable an d disable
hardware interrupts. The return from an interrupt uses
the RET I statemen t.
10 ONITR 0,500
20 A = A + 1
30 GOTO 20
500 PRINT A
510 A = 0
590 RETI