
4/29/2020
Godson 3A2000 / 3B2000 Processor User Manual
94
5
CDSR
1
R
Inverse of DSR input value, or connect to DTR in loopback mode
4
CCTS
1
R
Inverse of CTS input value, or connect to RTS in loopback mode
3
DDCD
1
R
DDCD indicator
2
TERI
1
R
RI edge detection. RI state changes from low to high
1
DDSR
1
R
DDSR indicator
0
DCTS
1
R
DCTS indicator
11.3.9
Frequency divider latch
Chinese name: Frequency Division Latch 1
Register bit width: [7: 0]
Offset: 0x00
Reset value: 0x00
Bit field
Bit field name
Bit width
access
description
7: 0
LSB
8
RW
Store the lower 8 bits of the divider latch
Chinese name: Frequency Division Latch 2
Register bit width: [7: 0]
Offset: 0x01
Reset value: 0x00
Bit field
Bit field name
Bit width
access
description
112
Page 117
Godson 3A2000 / 3B2000 Processor User Manual Part 1
7: 0
MSB
8
RW
Stores the upper 8 bits of the divider latch
11.4 SPI controller
The SPI controller has the following features:
● Full duplex synchronous serial data transmission
● Supports up to 4 variable-length byte transmission
● Main mode support
● Mode failure generates an error flag and issues an interrupt request
● Double buffer receiver
● Serial clock with programmable polarity and phase
● Can control SPI in wait mode
● Support boot from SPI
The physical address of the SPI controller register is 0x1FE00220.
Table 11-6 SPI controller address space distribution
Address name
Address range
size
SPI Boot
0X1FC0_0000-0X1FD0_0000
1MByte
SPI Memory
0X1D00_0000-0X1E00_0000
16MByte
SPI Register
0X1FE0_0220-0X1FE0_0230
16Byte
The SPI Boot address space is the address space that the processor first accesses when the system starts. When the PCI_CONFIG [0] pin is
When pulling up, the address of 0xBFC00000 is automatically routed to the SPI.
The SPI Memory space can also be accessed directly through the CPU's read request, its minimum 1M bytes and SPI BOOT space
overlapping.