SAF-C164SM Infineon Technologies, SAF-C164SM Datasheet - Page 97

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

Interrupt Priority Level and Group Level
The four bits of bit field ILVL specify the priority level of a service request for the
arbitration of simultaneous requests. The priority increases with the numerical value of
ILVL: so, 0000
When more than one interrupt request on a specific level becomes active at the same
time, the values in the respective bit fields GLVL are used for second level arbitration to
select one request to be serviced. Again, the group priority increases with the numerical
value of GLVL, so 00
Note: All interrupt request sources enabled and programmed to the same priority level
Upon entry into the interrupt service routine, the priority level of the source that won the
arbitration and whose priority level is higher than the current CPU level, is copied into bit
field ILVL of register PSW after pushing the old PSW contents onto the stack.
The interrupt system of the C164CM allows nesting of up to 15 interrupt service routines
of different priority levels (level 0 cannot be arbitrated).
Interrupt requests programmed to priority levels 15 or 14 (i.e., ILVL = 111X
serviced by the PEC unless the COUNT field of the associated PECC register contains
zero. In this case, the request will be serviced by normal interrupt processing instead.
Interrupt requests programmed to priority levels 13 through 1 will always be serviced by
normal interrupt processing.
Note: Priority level 0000
For interrupt requests which are to be serviced by the PEC, the associated PEC channel
number is derived from the respective ILVL (LSB) and GLVL (see
programming a source to priority level 15 (ILVL = 1111
7 … 4; programming a source to priority level 14 (ILVL = 1110
channel group 3 … 0. The actual PEC channel number is then determined by the group
priority field GLVL.
Simultaneous requests for PEC channels are prioritized according to the PEC channel
number, where channel 0 has lowest and channel 8 has highest priority.
Note: All sources requesting PEC service must be programmed to different PEC
User’s Manual
must always be programmed to different group priorities. Otherwise, an incorrect
interrupt vector will be generated.
will never be serviced because it can never interrupt the CPU. However, an
enabled interrupt request on level 0000
and reactivate the CPU.
channels. Otherwise, an incorrect PEC channel may be activated.
B
is the lowest and 1111
B
is the lowest and 11
B
is the default level of the CPU. Therefore, a request on level 0
B
is the highest priority level.
5-7
B
is the highest group priority.
B
will terminate the C164CM’s Idle mode
B
) selects the PEC channel group
Interrupt and Trap Functions
C164CM/C164SM
B
) selects the PEC
Figure
Derivatives
V1.0, 2002-02
B
5-1). So,
) will be