Programmable Four-Channel Communications Controller
—
CD2481
Datasheet
165
9.5.2.3
Receive Interrupt Status Register (RISR
This register reports the status of the channel during the receive interrupt service. It is a 16-bit
register, with the lower byte displaying current receive character oriented status while the upper
byte displays current DMA interrupt status. The upper byte is not used if DMA mode is not active.
Note:
During an interrupt service routine, the host can use this register to provide a timer value as
detailed in the Receive End of Interrupt register. The host can only load ne of the two timers in the
interrupt service routine.
RISRl
–
HDLC Mode
If RxData in IER is set, these interrupts are enabled.
Bit 7
Reserved
–
returns
‘
0
’
when read.
Bit 6
Receiving a data frame is essentially complete.
Bit 5
Received abort sequence terminating the frame.
Bit 4
CRC error on current frame.
Register Name: RISR
Register Description: Receive Interrupt Status Register
Default Value: x
’
00
Access: Word Read/Write
Intel Hex Address: x
’
8A
Motorola Hex Address: x
’
88
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
RISR High
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
RISR Low
Register Name: RISRl
Register Description: Receive Interrupt Status Register - Low
Default Value: x
’
00
Access: Byte Read Only
Intel Hex Address: x
’
8A
Motorola Hex Address: x
’
89
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
EOF
RxAbt
CRC
OE
Reslnd
0
ClrDct
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Binary Value for Timer