ST92196A STMicroelectronics, ST92196A Datasheet - Page 55

• Manufacturer Part Number: ST92196A
• Description: 8/16-bit Mcu For Tv Applications With Up To 96k Rom, On-screen-display And 1 Or 2 Data Slicers
• Manufacturer: STMicroelectronics

3.10 INTERRUPT REGISTERS
CENTRAL INTERRUPT CONTROL REGISTER
(CICR)
R230 - Read/Write
Register Group: System
Reset value: 1000 0111 (87h)
Bit 7 = GCEN: Global Counter Enable.
This bit enables the 16-bit Multifunction Timer pe-
ripheral.
0: MFT disabled
1: MFT enabled
Bit 6 = TLIP: Top Level Interrupt Pending .
This bit is set by hardware when Top Level Inter-
rupt (TLI) trigger event occurs. It is cleared by
hardware when a TLI is acknowledged. It can also
be set by software to implement a software TLI.
0: No TLI pending
1: TLI pending
Bit 5 = TLI: Top Level Interrupt.
This bit is set and cleared by software.
0: A Top Level Interrupt is generared when TLIP is
1: A Top Level Interrupt request is generated when
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GCEN TLIP
INTERRUPTS
set, only if TLNM=1 in the NICR register (inde-
pendently of the value of the IEN bit).
IEN=1 and the TLIP bit are set.
7
TLI
IEN
IAM CPL2 CPL1 CPL0
0
Bit 4 = IEN: Interrupt Enable .
This bit is cleared by the interrupt machine cycle
(except for a TLI).
It is set by the iret instruction (except for a return
from TLI).
It is set by the EI instruction.
It is cleared by the DI instruction.
0: Maskable interrupts disabled
1: Maskable Interrupts enabled
Note: The IEN bit can also be changed by soft-
ware using any instruction that operates on regis-
ter CICR, however in this case, take care to avoid
spurious interrupts, since IEN cannot be cleared in
the middle of an interrupt arbitration. Only modify
the IEN bit when interrupts are disabled or when
no peripheral can generate interrupts. For exam-
ple, if the state of IEN is not known in advance,
and its value must be restored from a previous
push of CICR on the stack, use the sequence DI;
POP CICR to make sure that no interrupts are be-
ing arbitrated when CICR is modified.
Bit 3 = IAM: Interrupt Arbitration Mode .
This bit is set and cleared by software.
0: Concurrent Mode
1: Nested Mode
Bit 2:0 = CPL[2:0]: Current Priority Level .
These bits define the Current Priority Level.
CPL=0 is the highest priority. CPL=7 is the lowest
priority. These bits may be modified directly by the
interrupt hardware when Nested Interrupt Mode is
used.