ST16C450 Exar Corporation, ST16C450 Datasheet - Page 8

• Manufacturer Part Number: ST16C450
• Description: UNIVERSAL ASYNCHRONOUS RECEIVER/TRANSMITTER (UART)
• Manufacturer: Exar Corporation

ST16C450
FUNCTIONAL DESCRIPTIONS
Internal Registers
The ST16C450 provides 11 internal registers for
monitoring and control. These registers are shown in
Table 2 below. These registers function as data holding
registers (THR/RHR), interrupt status and control
registers (IER/ISR), line status and control registers,
(LCR/LSR), modem status and control registers (MCR/
MSR), programmable data rate (clock) control registers
(DLL/DLM), and a user assessable scratchpad register
(SPR).
Note *3: These registers are accessible only when LCR bit-7 is set to a logic 1.
Rev. 4.20
A2
0
0
0
0
1
1
1
1
0
0
Table 2, INTERNAL REGISTER DECODE
General Register Set (THR/RHR, IER/ISR, MCR/MSR, LCR/LSR, SPR):
Baud Rate Register Set (DLL/DLM): Note *3
A1
0
0
1
1
0
0
1
1
0
0
A0
0
1
0
1
0
1
0
1
0
1
READ MODE
Receive Holding Register
Interrupt Status Register
Line Status Register
Modem Status Register
Scratchpad Register
LSB of Divisor Latch
MSB of Divisor Latch
8
WRITE MODE
Transmit Holding Register
Interrupt Enable Register
Line Control Register
Modem Control Register
Scratchpad Register
LSB of Divisor Latch
MSB of Divisor Latch