Philips Semiconductors Product data sheet
SCC2691Universal asynchronous receiver/transmitter (UART)
2006 Aug 04 11
Table 2. Register Bit FormatsBit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
MR1 (Mode Register 1)
RxRTS Control RxINT Select Error Mode* Parity Mode Parity Type Bits per Character
0 = no
1 = yes 0 = RxRDY
1 = FFULL 0 = Char
1 = Block 00 = With parity
01 = Force parity
10 = No parity
11 = Special mode
0 = Even
1 = Odd 00 = 5
01 = 6
10 = 7
11 = 8
NOTE:
*In block error mode, block error conditions must be cleared by using the error reset command (command 4x) or a receiver reset.
MR2 (Mode Register 2)
Channel Mode TxRTS
Control CTS Enable
Tx Stop Bit Length*
00 = Normal
01 = Auto echo
10 = Local loop
11 = Remote loop
0 = No
1 = Yes 0 = No
1 = Yes 0 = 0.563 4 = 0.813 8 =1.563 C = 1.813
1 = 0.625 5 = 0.875 9 = 1.625 D = 1.875
2 = 0.688 6 = 0.938 A = 1.688 E = 1.938
3 = 0.750 7 = 1.000 B = 1.750 F = 2.000
NOTE: *Add 0.5 to values shown for 0–7 if channel is programmed for 5 bits/character.
CSR (Clock Select Register)
Receiver Clock Select Transmitter Clock Select
See Text See Text
See Table 6 for BRG Test frequencies in this data sheet, and
“Extended baud rates for SCN2681, SCN68681, SCC2691, SCC2692, SCC68681
and SCC2698B”
Philips Semiconductors ICs for Data Communications, IC-19, 1994.
CR (Command Register)
Miscellaneous Commands Disable Tx Enable Tx Disable Rx Enable Rx
See Text 0 = No
1 = Yes 0 = No
1 = Yes 0 = No
1 = Yes 0 = No
1 = Yes
NOTE:
Access to the miscellaneous commands should be separated by 3 X1 clock edges. A disabled transmitter cannot be loaded.
SR (Channel Status Register)
Received Break Framing
Error Parity
Error Overrun
Error TxEMT TxRDY FFULL RxRDY
0 = No
1 = Yes
*
0 = No
1 = Yes
*
0 = No
1 = Yes
*
0 = No
1 = Yes 0 = No
1 = Yes 0 = No
1 = Yes 0 = No
1 = Yes 0 = No
1 = Yes
NOTE:
*These status bits are appended to the corresponding data character in the receive FIFO. A read of the status register provides these bits [7:5]
from the top of the FIFO together with bits [4;0]. These bits are cleared by a reset error status command. In character mode they are reset when
the corresponding data character is read from the FIFO. In block error mode, block error conditions must be cleared by using the error reset
command (command 4x) or a receiver reset.
ACR (Auxiliary Control Register)
BRG Set
Select Counter/Timer
Mode and Source Power-Down
Mode MPO Pin
Function Select
0 = Set 1
1 = Set 2 See Text 0 = On
PWRDN Active
1 = Off
Normal
000 = RTSN 100 = RxC (1X)
001 = C/TO 101 = RxC (16X)
010 = TxC (1X) 110 = TxRDY
011 = TxC (16X) 111 = RxRDY/FFULL
ISR (Interrupt Status Register)
MPI Pin
Change MPI Pin
Current State Not used Counter
Ready Delta
Break RxRDY/
FFULL TxEMT TxRDY
0 = No
1 = Yes 0 = Low
1 = High 0 = No
1 = Yes 0 = No
1 = Yes 0 = No
1 = Yes 0 = No
1 = Yes 0 = No
1 = Yes
IMR (Interrupt Mask Resister)
MPI Change
Interrupt MPI Level
Interrupt Not used Counter
Ready Int Delta Break
Interrupt RxRDY/FFULL
Interrupt TxEMT
Interrupt TxRDY
Interrupt
0 = Off
1 = On 0 = Off
1 = On 0 = Off
1 = On 0 = Off
1 = On 0 = Off
1 = On 0 = Off
1 = On 0 = Off
1 = On