xr68c92 Exar Corporation, xr68c92 Datasheet - Page 17

• Manufacturer Part Number: xr68c92
• Description: Xr68c92 -dual Uart With Eight Bytes Transmit And Receive Fifo
• Manufacturer: Exar Corporation

MODE REGISTER 0 (MR0A, MR0B)
This register is accessed only when command is
applied via CRA, CRB register (upper nibble = 0xB).
After reading or writing to MR0A (or MR0B) register,
the mode register pointer will point to MR1A (or MR1B)
register.
MR0A Bit-0:
Extended baud rate table selection for both channels.
MR0A Bit-1: Special Function.
MR0A Bit-2:
Extended baud rate table selection for both channels.
0 = Normal baud rate tables
1 = Extend baud rate tables 2
MR0A Bit-3, MR0B Bits 3-0:
Not Used. Any write to this bit is ignored.
MR0A, MR0B Bits 5-4:
Transmit trigger level select.
Bit-5
Bit-5
MR0A, MR0B Bit-6:
Receive trigger level select. This bit is associated with
MR1 Bit-6.
MR0 Bit-6
MR0 Bit-6
0 = Normal baud rate tables
1 = Extended baud rate tables 1
0 = Normal
1 = Factory test mode
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
Rev. 1.33
Bit-4
Bit-4
0
1
0
1
0
1
0
1
MR1 Bit-6
MR1 Bit-6
0
1
0
1
0
1
0
1
16 FIFO locations empty (default)
12 FIFO locations empty
6 FIFO locations empty
1 FIFO location empty
8 FIFO locations empty (default)
4 FIFO locations empty
6 FIFO locations empty
1 FIFO location empty
XR68C192
XR68C92
12 bytes in FIFO
16 bytes in FIFO
1 byte in FIFO (default)
3 bytes in FIFO
6 bytes in FIFO
8 bytes in FIFO
1 byte in FIFO (default)
6 bytes in FIFO
XR68C92
XR68C192
17
MR0A, MR0B Bit-7:
Receive time-out (watch dog timer).
0 = Disabled (default)
1 = Enabled
See description under 'Watchdog Timer'.
MODE REGISTER 1 (MR1A, MR1B)
MR1A, MR1B are accessed after reset or by command
applied via CRA, CRB register (upper nibble = 0x1).
After reading or writing to MR1A (or MR1B) register,
the mode register pointer will point to MR2A (or MR2B)
register.
MR1A, MR1B Bits 1-0:
Character Length
0 0 = 5 (default)
0 1 = 6
MR1A, MR1B Bit-2:
In non-Multidrop mode, this bit selects the parity.
0 = Even Parity (default)
1 = Odd Parity
In Multidrop mode, this bit is the Address/Data flag.
0 = Data (default)
1 = Address
MR1A, MR1B Bit 4-3: Parity mode.
00 = With parity (default)
01 = Force parity
MR1A, MR1B Bit-5: Data error mode.
0 = Single Character mode (default)
1 = Block (FIFO) mode
MR1A, MR1B Bit-6.
Receive trigger levels. See description under MR0 bit-
6.
MR1A, MR1B Bit-7: Receive RTS flow control.
0 = No RX RTS control function (default)
1 = Auto RX RTS control function
The output OP0 (OP1) serves as the -RTS signal for
channel A (channel B). Note that MR2 A/B bit-5 also
controls OP0 (OP1). Only one of MR1 bit-7 or MR2 bit-
5 should be set to '1'.
MODE REGISTER 2 (MR2A, MR2B)
This register is accessed after any read or write
operation to MR1A (or MR1B) register is performed.
Any read or write to MR2A (or MR2B) does not change
the mode register pointer. User should use one of the
XR68C92/192
1 0 = 7
1 1 = 8
10 = No parity
11 = Multidrop mode