
4/29/2020
Godson 3A2000 / 3B2000 Processor User Manual
90
7: 4
Reserved
4
RW
Keep
3
IME
1
RW
Modem status interrupt enable '0' – close '1' – open
2
ILE
1
RW
Receiver line status interrupt enable '0' – close '1' – open
1
ITxE
1
RW
Transfer save register is empty Interrupt enable '0' – close '1' – open
0
IRxE
1
RW
Receive valid data interrupt enable '0' – close '1' – open
11.3.3
Interrupt Identification Register ( IIR )
Chinese name: Interrupt source register
Register bit width: [7: 0]
Offset: 0x02
Reset value: 0xc1
Bit field
Bit field name
Bit width access
description
7: 4
Reserved
4
R
Keep
3: 1
II
3
R
Interrupt source display bit, see the table below for details
0
INTp
1
R
Interrupt indication bit
Interrupt control function table
107
Page 112
Godson 3A2000 / 3B2000 Processor User Manual Part 1
Bit 3 Bit 2 Bit 1 Priority interrupt type
Interrupt source
Interrupt reset control
0
1
1
1st
Receive line status
Parity, overflow, or frame error, or hit
Interrupt
Read LSR
0
1
0
2nd
Received valid number
according to
The number of characters in the FIFO reaches
trigger level
Low number of characters in FIFO
Value for trigger
1
1
0
2nd
Receive timeout
There is at least one character in the FIFO,
But within 4 character time
Operations, including read and write operations
Read receive FIFO
0
0
1
3rd
Transfer, save, deposit
The device is empty
Transfer save register is empty
Write data to THR or
Multi IIR
0
0
0
4th
Modem status
CTS, DSR, RI or DCD.
Read MSR
11.3.4
FIFO control register ( FCR )
Chinese name: FIFO control register
Register bit width: [7: 0]
Offset: 0x02
Reset value: 0xc0
Bit field
Bit field name
Bit width access
description
7: 6
TL
2
W
Receive FIFO trigger value for interrupt request
'00' – 1 byte '01' – 4 bytes
'10' – 8 bytes '11' – 14 bytes
5: 3
Reserved
3
W
Keep