XR20V2170 Datasheet, PDF (12/52 Pages) Exar Corporation – I2C/SPI UART WITH 64-BYTE FIFO AND RS232 TRANSCEIVER

XR20V2170
I2C/SPI UART WITH 64-BYTE FIFO AND RS232 TRANSCEIVER
REV. 1.0.0
TABLE 6: TYPICAL DATA RATES WITH A 24 MHZ CRYSTAL OR EXTERNAL CLOCK AT 16X SAMPLING
Required
Output Data
Rate
400
2400
4800
9600
10000
19200
25000
28800
38400
50000
57600
75000
100000
115200
153600
200000
225000
230400
250000
DIVISOR FOR
16x Clock
(Decimal)
3750
625
312.5
156.25
150
78.125
60
52.0833
39.0625
30
26.0417
20
15
13.0208
9.7656
7.5
6.6667
6.5104
6
DIVISOR
OBTAINABLE IN
V2170
DLM PROGRAM
VALUE (HEX)
DLL PROGRAM
VALUE (HEX)
DLD PROGRAM
VALUE (HEX)
DATA ERROR
RATE (%)
3750
E
A6
0
0
625
2
71
0
0
312 8/16
1
38
8
0
156 4/16
0
9C
4
0
150
0
96
0
0
78 2/16
0
4E
2
0
60
0
3C
0
0
52 1/16
0
34
1
0.04
39 1/16
0
27
1
0
30
0
1E
0
0
26 1/16
0
1A
1
0.08
20
0
14
0
0
15
0
F
0
0
13
0
D
0
0.16
9 12/16
0
9
C
0.16
7 8/16
0
7
8
0
6 11/16
0
6
B
0.31
6 8/16
0
6
8
0.16
6
0
6
0
0
2.8 Transmitter
The transmitter section comprises of an 8-bit Transmit Shift Register (TSR) and 64 bytes of FIFO which
includes a byte-wide Transmit Holding Register (THR). TSR shifts out every data bit with the 16X/8X/4X
internal clock. A bit time is 16 (8 if 8X or 4 if 4X) clock periods (see DLD[5:4]). The transmitter sends the start-
bit followed by the number of data bits, inserts the proper parity-bit if enabled, and adds the stop-bit(s). The
status of the FIFO and TSR are reported in the Line Status Register (LSR[6:5]).
2.8.1 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 64 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.
12