
CD2481
—
Programmable Four-Channel Communications Controller
162
Datasheet
9.5.1.3
Local Interrupting Channel Register (LICR)
These per-channel registers are initialized with each channel number. The locations are RAM
registers and can be used for any purpose.
Bits 7:4
User-defined
Bits 3:2
Defines the interrupting channel number
Bits 1:0
User-defined
9.5.1.4
Interrupt Stack Register (STK)
This register is a 4-bit-deep by 2-bit-wide stack that holds the internal interrupt nesting history. The
stack is pushed from bits 7 and 0 towards the center during an interrupt acknowledge cycle and
popped from the center during a write to an end of interrupt register.
Bits 7, 0
CLvl [0:1]These bits provide the currently active interrupt level.
Register Name: LICR
Register Description: Local Interrupting Channel Register
Default Value: C1:C0 contain channel number
Access: Byte Read/Write
Intel Hex Address: x
’
25
Motorola Hex Address: x
’
26
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
X
X
X
X
C1
C0
X
X
C1
C0
Channel Number
0
0
Channel 0
0
1
Channel 1
1
0
Channel 2
1
1
Channel 3
Register Name: STK
Register Description: Interrupt Stack Register
Default Value: x
’
00
Access: Byte Read Only
Intel Hex Address: x
’
E0
Motorola Hex Address: x
’
E2
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
CLvl [1]
MLvl [1]
TLvl [1]
0
0
TLvl [0]
MLvl [0]
CLvl [0]