
W83877ATF
Publication Release Date: April 1998
- 40 -
Version 0.51
3.2 Register Address
TABLE 3-1 UART Register Bit Map
Bit Number
1
2
Register Address Base
0
3
4
5
6
7
8
BDLAB = 0
Receiver
Buffer
Register
(Read Only)
RBR
RX Data
Bit 0
RX Data
Bit 1
RX Data
Bit 2
RX Data
Bit 3
RX Data
Bit 4
RX Data
Bit 5
RX Data
Bit 6
RX Data
Bit 7
8
BDLAB = 0
Transmitter
Buffer Register
(Write Only)
Interrupt Control
Register
TBR
TX Data
Bit 0
TX Data
Bit 1
TX Data
Bit 2
TX Data
Bit 3
TX Data
Bit 4
TX Data
Bit 5
TX Data
Bit 6
TX Data
Bit 7
9
BDLAB = 0
ICR
RBR Data
Ready
Interrupt
Enable
(ERDRI)
TBR
Empty
Interrupt
Enable
(ETBREI)
USR
Interrupt
Enable
(EUSRI)
HSR
Interrupt
Enable
(EHSRI)
0
0
0
0
A
Interrupt Status
Register
(Read Only)
ISR
"0" if Interrupt
Pending
Interrupt
Status
Bit (0)
Interrupt
Status
Bit (1)
Interrupt
Status
Bit (2)**
0
0
FIFOs
Enabled
**
FIFOs
Enabled
**
A
UART FIFO
Control
Register
(Write Only)
UART Control
Register
UFR
FIFO
Enable
RCVR
FIFO
Reset
XMIT
FIFO
Reset
DMA
Mode
Select
Reserved
Reversed
RX
Interrupt
Active Level
(LSB)
Set
Silence
Enable
(SSE)
RX
Interrupt
Active Level
(MSB)
Baud rate
Divisor
Latch
Access Bit
(BDLAB)
B
UCR
Data
Length
Select
Bit 0
(DLS0)
Data
Length
Select
Bit 1
(DLS1)
Multiple
Stop Bits
Enable
(MSBE)
Parity
Bit
Enable
(PBE)
Even
Parity
Enable
(EPE)
Parity
Bit Fixed
Enable
PBFE)
C
Handshake
Control
Register
HCR
Data
Terminal
Ready
(DTR)
RBR Data
Ready
(RDR)
Request
to
Send
(RTS)
Overrun
Error
(OER)
Loopback
RI
Input
IRQ
Enable
Internal
Loopback
Enable
0
0
0
D
UART Status
Register
USR
Parity Bit
Error
(PBER)
No Stop
Bit
Error
(NSER)
Silent
Byte
Detected
(SBD)
TBR
Empty
(TBRE)
TSR
Empty
(TSRE)
RX FIFO
Error
Indication
(RFEI) **
E
Handshake
Status Register
HSR
CTS
Toggling
(TCTS)
DSR
Toggling
(TDSR)
RI Falling
Edge
(FERI)
DCD
Toggling
(TDCD)
Clear
to Send
(CTS)
Data Set
Ready
(DSR)
Ring
Indicator
(RI)
Data Carrier
Detect
(DCD)
F
User Defined
Register
Baudrate Divisor
Latch Low
UDR
Bit 0
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
8
BDLAB = 1
BLL
Bit 0
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
9
BDLAB = 1
Baudrate Divisor
Latch High
BHL
Bit 8
Bit 9
Bit 10
Bit 11
Bit 12
Bit 13
Bit 14
Bit 15
*: Bit 0 is the least significant bit. The least significant bit is the first bit serially transmitted or received.
**: These bits are always 0 in 16450 mode.