cx20493-35/app Conexant Systems, Inc., cx20493-35/app Datasheet - Page 88

• Manufacturer Part Number: cx20493-35/app
• Description: With Cx20493 Smartdaa?
• Manufacturer: Conexant Systems, Inc.

5.2.10
5.3
5.3.1
5-10
CX81801-7x/8x SmartV.XX Modem in 128-Pin LQFP with CX20493 in 32-Pin LQFP Data Sheet
Divisor Registers (Addr = 0 and 1, DLAB = 1)
Receiver FIFO Interrupt Operation
Receiver Data Available Interrupt
The Divisor Latch LS (least significant byte) and Divisor Latch MS (most significant
byte) are two read-write registers at locations 0 and 1 when DLAB = 1, respectively.
The baud rate is selected by loading each divisor latch with the appropriate hex value.
Programmable values corresponding to the desired baud rate are listed in Table 5-3.
1. SCR - Scratch Register (Addr = 7)
The Scratchpad Register is a read-write register at location 7. This register is not used by
the modem and can be used by the host for temporary storage.
Table 5-3. Programmable Baud Rates
When the FIFO mode is enabled (FCR0 = 1) and receiver interrupt (RX Data Available)
is enabled (IER0 = 1), receiver interrupt operation is as follows:
The Receiver Data Available Flag (LSR0) is set as soon as a received data character is
available in the RX FIFO. LSR0 is cleared when the RX FIFO is empty.
The Receiver Data Available interrupt code (IIR0-IIR4 = 4h) is set whenever the number
of received data bytes in the RX FIFO reaches the trigger level specified by FCR6-FCR7
bits; it is cleared whenever the number of received data bytes in the RX FIFO drops
below the trigger level specified by FCR6-FCR7 bits.
The HINT interrupt is asserted whenever the number of received data bytes in the RX
FIFO reaches the trigger level specified by FCR6-FCR7 bits. HINT interrupt is de-
asserted when the number of received data bytes in the RX FIFO drops below the trigger
level specified by FCR6-FCR7 bits.
Divisor Latch (Hex)
MS
06
04
03
01
00
00
00
00
00
00
00
00
00
00
00
LS
C0
0C
00
17
00
80
60
30
18
06
04
03
02
01
00
Conexant
Divisor (Decimal)
1536
1047
768
384
192
NA
96
48
24
12
6
4
3
2
1
Baud Rate
115200
230400
19200
28800
38400
57600
1200
2400
4800
9600
110
150
300
600
75
102247B