XR16M598 Datasheet, PDF (12/58 Pages) Exar Corporation – 1.62V TO 3.63V HIGH PERFORMANCE OCTAL UART WITH 16-BYTE FIFO

XR16M598
1.62V TO 3.63V HIGH PERFORMANCE OCTAL UART WITH 16-BYTE FIFO
REV. 1.0.0
2.7.1 Transmit Holding Register (THR) - Write Only
The transmit holding register is an 8-bit register providing a data interface to the host processor. The host
writes transmit data byte to the THR to be converted into a serial data stream including start-bit, data bits,
parity-bit and stop-bit(s). The least-significant-bit (Bit-0) becomes first data bit to go out. The THR is the input
register to the transmit FIFO of 16 bytes when FIFO operation is enabled by FCR bit-0. Every time a write
operation is made to the THR, the FIFO data pointer is automatically bumped to the next sequential data
location.
2.7.2 Transmitter Operation in non-FIFO Mode
The host loads transmit data to THR one character at a time. The THR empty flag (LSR bit-5) is set when the
data byte is transferred to TSR. THR flag can generate a transmit empty interrupt (ISR bit-1) when it is enabled
by IER bit-1. The TSR flag (LSR bit-6) is set when TSR becomes completely empty.
FIGURE 5. TRANSMITTER OPERATION IN NON-FIFO MODE
Data
Byte
Transmit
Holding
Register
(THR)
THR Interrupt (ISR bit-1)
Enabled by IER bit-1
16X or 8X or 4X Clock
Transmit Shift Register (TSR)
M
L
S
S
B
B
TXNOFIFO1
12