SAF-C164SM Infineon Technologies, SAF-C164SM Datasheet - Page 434

• Manufacturer Part Number: SAF-C164SM
• Description: 16-Bit CMOS Microcontroller
• Manufacturer: Infineon Technologies

22.6
All communication between peripherals and the CPU is performed by either PEC
transfers to and from internal memory or by explicit addressing of the SFRs associated
with the specific peripherals. After resetting the C164CM all peripherals (except the
watchdog timer) are disabled and initialized to default values. A desired configuration of
a specific peripheral is programmed using MOV instructions of either constants or
memory values to specific SFRs. Specific control flags may also be altered via bit
instructions.
Once in operation, the peripheral operates autonomously until an end condition is
reached; at which time, it requests a PEC transfer or requests CPU servicing through an
interrupt routine. Information may also be polled from peripherals through read accesses
to SFRs or bit operations including branch tests on specific control bits in SFRs. To
ensure proper allocation of peripherals among multiple tasks, a portion of the internal
memory has been made bit-addressable to allow user semaphores. Instructions have
also been provided to lock out tasks via software by setting or clearing user-specific bits
and conditionally branching based on these specific bits.
It is recommended that bit fields in control SFRs be updated using the BFLDH and
BFLDL instructions or a MOV instruction to avoid undesired intermediate modes of
operation which can occur if BCLR/BSET or AND/OR instruction sequences are used.
22.7
Interrupt routines are entered when a requesting interrupt has a priority higher than the
current CPU priority level. Traps are entered regardless of the current CPU priority.
When either a trap or interrupt routine is entered, the state of the machine is preserved
on the system stack and a branch to the appropriate trap/interrupt vector is made.
All trap and interrupt routines require the use of the RETI (return from interrupt)
instruction to exit from the called routine. This instruction restores the system state from
the system stack and then branches back to the location at which the trap or interrupt
occurred.
User’s Manual
Peripheral Control and Interface
Trap/Interrupt Entry and Exit
22-13
System Programming
C164CM/C164SM
Derivatives
V1.0, 2002-02