C161U
Interrupt and Trap Functions
Preliminary Data Sheet
113
02.2000
PRELIMINARY
PRE
LI
M
INAR
Y
- E
XCE
RP
T
-
xxIC (yyyy
H / zzH)
<SFR area>
Reset Value: - - 00
H
The Interrupt Request Flag is set by hardware whenever a service request from the
respective source occurs. It is cleared automatically upon entry into the interrupt service
routine or upon a PEC service. In the case of PEC service the Interrupt Request flag
remains set, if the COUNT field in register PECCx of the selected PEC channel
decrements to zero. This allows a normal CPU interrupt to respond to a completed PEC
block transfer.
Note: Modifying the Interrupt Request flag via software causes the same effects as if it
had been set or cleared by hardware.
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 0000B is the lowest and 1111B is the highest priority level.
When more than one interrupt request on a specific level gets active at the same time,
the values in the respective bit fields GLVL are used for second level arbitration to select
one request for being serviced. Again the group priority increases with the numerical
value of GLVL, so 00B is the lowest and 11B is the highest group priority.
Bit
Function
GLVL
Group Level
Defines the internal order for simultaneous requests of the same priority.
3: Highest group priority
0: Lowest group priority
ILVL
Interrupt Priority Level
Defines the priority level for the arbitration of requests.
F
H: Highest priority level
0
H: Lowest priority level
xxIE
Interrupt Enable Control Bit (individually enables/disables a specific source)
‘0’: Interrupt request is disabled
‘1’: Interrupt Request is enabled
xxIR
Interrupt Request Flag
‘0’: No request pending
‘1’: This source has raised an interrupt request
5
4
3
2
1
0
11
10
9
8
7
6
15
14
13
12
rw
-
rw
-
xxIE
xxIR
GLVL
ILVL