mcs7840 MosChip, mcs7840 Datasheet - Page 9

• Manufacturer Part Number: mcs7840
• Description: Usb-2.0 To Four Serial Ports
• Manufacturer: MosChip

Rev.
UART Register-Set and Register Descriptions
The UART has 10 registers, but only three address lines to access those registers. The mapping of the
registers is dependent upon the Line Control Register (LCR).
LCR[7] enables the Divider Latch Registers (DLL & DLM).
The following table gives the various UART registers and their offsets.
Register
Name
MCR
MSR
RHR
DLM
THR
FCR
LCR
SPR
LSR
DLL
IER
ISR
1.2
Offset R/W Bit-7
0
0
1
2
2
3
4
5
6
7
0
1
Additional standard registers - these are accessed when LCR[7] = 1
R/W
R/W DLE
R/W
R/W
R/W
R/W
W
W
R
R
R
R
Error
Trigger Level
Data
DCD
DTR – DSR/
Flow Control
Enabled
FIFOs
RHR
DCD
Empty
Break
Bit-6
Reserved
Tx
Tx
RI
Data to be transmitted ( Transmitter Holding Register)
Data to be received (Receiver Holding Register)
RTS/CTS
Control
Empty
Force
Parity
Bit-5
Flow
DSR
THR
Reserved
Reserved
Odd/Even
Divisor Latch bits[15:8]
Divisor Latch bits[7:0]
Scratch Pad Register
Sleep
Mode
Parity
Break
Bit-4
Loop
CTS
Rx
Reserved
Framing
Modem
Enable
USB-2.0 to Four Serial Ports
ΔDCD
Parity
Mask
Bit-3
Error
Int
Unused
Interrupt Priority
MCS7840
Parity
Flush
Mask
Bit-2
Error
THR
Stop
Stat
Bits
Teri
Rx
Int
Overrun
Tx Rdy
ΔDSR
Flush
Mask
Bit-1
Error
RHR
RTS
Int
Data Length
Interrupt
Pending
Rx Rdy
Enable
ΔCTS
Mask
Bit-0
FIFO
DTR
Rdy
Rx
Int
Page 9