scn68652 NXP Semiconductors, scn68652 Datasheet - Page 15

• Manufacturer Part Number: scn68652
• Description: Multi-protocol Communications Controller Mpcc
• Manufacturer: NXP Semiconductors

Philips Semiconductors
Table 7.
1995 May 01
Multi-protocol communications controller (MPCC)
00–07
12–14
BIT
08
09
10
11
15
Transmit Data/Status Register (TDSR) (R/W except TDSR15)
Not Defined
TABORT
NAME
TSOM
TEOM
TERR
TxDB
TGA
BOP/BCP
MODE
Read
BOP
BOP
BOP
BOP
BOP
BCP
BCP
BCP
only
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 PCSAR
preset to 1’s.
TSOM = 1 generates SYNCs from PCSAR
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 PCSAR
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)
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.
15
L
or transmits from TxDB for IDLE = 0 or 1
SCN2652/SCN68652
8–10
, should be CRC–CCITT
Product specification
L