Philips SCC2691 User Manual

Page 11

Philips Semiconductors

Product data sheet

SCC2691

Universal asynchronous receiver/transmitter (UART)

2006 Aug 04

Table 2.

Register Bit Formats

Bit 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

Stop Bit Length*

00 = Normal
01 = Auto echo
10 = Local loop
11 = Remote loop

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 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