2.0 Hardware Interface
RC224ATL/224ATLV
EmbeddedModem Family
The parallel interface registers are identified in Table 2-1.
Table 2-1. Parallel Interface Registers (1 of 2)
Bit Number
Register Register
Number
Name
7
6
5
4
3
2
1
0
7
Scratch
Register
(SCR)
Scratch Register
Clear to Delta Data Trailing
6
Modem
Status
Register
(MSR)
Data
Ring
Indicator
(RI)
Data Set
Ready
(DSR)
Delta Data Delta Clear
Set Ready to Send
Carrier
Detect
(DCD)
Send (CTS) Carrier
Detect
Edge of
Ring
Indicator
(DDSR)
(DCTS)
(DDCD)
(TERI)
5
4
3
2
Line Status
Register
(LSR)
0
Transmitter Transmitter Break
Framing
Error (FE) (PE)
ParityError Overrun
Data Ready
Empty
(TEMT)
Holding
Register
(THRE)
Interrupt
(BI)
Error (OE) (DR)
Modem
Control
Register
(MCR)
0
0
0
Local
Loopback
Out 2
Out 1
Request to Data
Send (RTS) Terminal
Ready
(DTR)
Line
Divisor
Latch
Access Bit
Set Break Stick Parity Even Parity Parity
Number of Word
Word
Length
Control
Register
(LCR)
(SB)
(SP)
Select
(EPS)
Enable
(PEN)
Stop Bits
(STB)
Length
Select Bit 1 Select Bit 0
(WLS1)
(DLAB)
(WLS0)
Interrupt
Identify
Register
(IIR) (Read
Only)
0
0
0
0
0
0
0
0
Pending
Pending
0 if
InterruptID InterruptID Interrupt
Bit 1
(PL1)
Bit 0
(PL0)
Pending
(IP)
1
Interrupt
0
Enable
Enable
Enable
Enable
DLAB = 0 Enable
Modem
Status
Receiver
Line Status Holding
Transmitter Received
Register
Data
(IER)
Interrupt
(EDSSI)
Interrupt
(ELSI)
Register
Empty
Interrupt
(ETBEI)
Available
Interrupt
(ERBFI)
0
Transmitter
DLAB = 0 Holding
Transmitter Holding Register (Write Only)
Receiver Buffer Register (Read Only)
Register
(THR)
0
Receiver
DLAB = 0 Buffer
Register
(RBR)
2-4
Conexant
D224ATLVDSC
CONEXANT [ CONEXANT SYSTEMS, INC ]
