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C165H
Architectural Overview
Data Sheet
34
2001-04-19
PRELMNARY
The PEC contains a set of SFRs which store the count value and control bits for eight
data transfer channels. In addition, the PEC uses a dedicated area of RAM which
contains the source and destination addresses. The PEC is controlled similar to any
other peripheral through SFRs containing the desired configuration of each channel.
An individual PEC transfer counter is implicitly decremented for each PEC service
except forming in the continuous transfer mode. When this counter reaches zero, a
standard interrupt is performed to the vector location related to the corresponding
source. PEC services are very well suited, for example, to move register contents to/from
-EXCERPT-
With an interrupt response time within a range from just 140 ns to 280 ns (in case of
internal program execution), the C165H is capable of reacting very fast on non-
deterministic events.
Its fast external interrupt inputs are sampled every 28 ns and allow to recognize even
very short external signals.
or error conditions that arise during run-time, so called 'Hardware Traps'. Hardware traps
cause an immediate non-maskable system reaction which is similiar to a standard
interrupt service (branching to a dedicated vector table location). The occurrence of a
hardware trap is additionally signified by an individual bit in the trap flag register (TFR).
Except for another higher prioritized trap service being in progress, a hardware trap will
interrupt any current program execution. In turn, hardware trap services can normally not
be interrupted by standard or PEC interrupts.
Software interrupts are supported by means of the 'TRAP' instruction in combination with
an individual trap (interrupt) number.
3.2
On-Chip System Resources
C165H controllers provide a number of powerful system resources designed around the
CPU. The combination of CPU and these resources results in the high performance of
the members of this controller family.
Peripheral Event Controller (PEC) and Interrupt Control
The Peripheral Event Controller allows to respond to an interrupt request with a single
data transfer (word or byte) which only consumes one instruction cycle and does not
require to save and restore the machine status. Each interrupt source is prioritized every
machine cycle in the interrupt control block. If PEC service is selected, a PEC transfer is
started. If CPU interrupt service is requested, the current CPU priority level stored in the
PSW register is tested to determine whether a higher priority interrupt is currently being
serviced. When an interrupt is acknowledged, the current state of the machine is saved
on the internal system stack and the CPU branches to the system specific vector for the
peripheral.