19.10.1 Operation During Interrupts
The Scanner Interrupt Management Mode Select (INTM) bit determines scanner priority during an interrupt event.
0
and the MD
bits select Burst mode, scanner operation is given higher priority than the interrupt
response. This allows the scanner to delay the interrupt response until the scan
operation is complete, but at the expense of increased interrupt response time.When INTM = 0
and the MD bits select Concurrent or Triggered modes, the
scanner accesses memory during the interrupt response. Scanner hardware will stall the
CPU while the scan operation is in progress. Once the scan is complete, CPU operation
resumes, allowing the interrupt response to resume. Interrupt response time is increased
by one instruction cycle each time the scanner accesses memory during the interrupt
response.
When INTM = 1
, the interrupt response is given higher priority than the
scanner operation. Scanner operation is delayed until the interrupt response is
complete. This allows interrupts to be serviced immediately, but decreases scanner
throughput time.
The INTM bit has no effect on scanner or interrupt priority in Peek mode.