SCN2652 データシートの表示（PDF） - Philips Electronics

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SCN2652

Multi-protocol communications controller(MPCC)

Philips Electronics 

Philips Semiconductors

Multi-protocol communications controller (MPCC)

Product specification

SCN2652/SCN68652

Table 7.

BIT

00–07

08

09

10

11

12–14

15

Transmit Data/Status Register (TDSR) (R/W except TDSR15)

NAME

TxDB

TSOM

TEOM

TABORT

TGA

Not Defined

TERR

MODE

BOP/BCP

BOP

BCP

BOP

BCP

BOP

BOP

FUNCTION

Transmit data buffer. Contains processor loaded characters to be serialized in TxSR and

transmitted on TxSO.

Transmitter start of message. Set by the processor to initiate message transmission provided

TxE = 1.

TSOM = 1 generates FLAGs. When TSOM = 0 transmission is from TxDB and FCS

generation (if specified) begins. FCS, as specified by PCSAR8–10, should be CRC–CCITT

preset to 1’s.

TSOM = 1 generates SYNCs from PCSARL or transmits from TxDB for IDLE = 0 or 1

respectively. When TSOM = 0 transmission is from TxDB and CRC generation (if specified)

begins.

Transmit end of message. Used to terminate a transmitted message.

TEOM = 1 causes the FCS and the closing FLAG to be transmitted following the transmission

of the data character in TxSR. FLAGs are transmitted until TEOM = 0. ABORT or GA are

transmitted if TABORT or TGA are set when TEOM = 1.

TEOM = 1 causes CRC–16 to be transmitted (if selected) followed by SYNCs from PCSARL

or TxDB (IDLE = 0 or 1). Clearing TEOM prior to the end of CRC–16 transmission (when

TxBE = 1) causes TxSO to be marked following the CRC–16. TxE must be dropped before a

new message can be initiated. If CRC is not selected, TEOM should not be set.

Transmitter abort = 1 will cause ABORT or FLAG to be sent (IDLE = 1 or 1) after the current

character is transmitted. (ABORT = 11111111)

Transmit go ahead (GA) instead of FLAG when TEOM = 1. This facilitates repeater

termination in loop mode. (GA = 01111111)

Read

only

BOP

BCP

Transmitter error = 1 indicates the TxDB has not been loaded in time (one character time–1/2

TxC period after TxBE is asserted) to maintain continuous transmission. TxU will be asserted

to inform the processor of this condition. TERR is cleared by setting TSOM. See timing

diagram.

ABORT’s or FLAG’s are sent as fill characters (IDLE = 0 or 1)

SYNC’s or MARK’s are sent as fill characters (IDLE = 0 or 1). For IDLE = 1 the last character

before underrun is not valid.

1995 May 01

15

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