scn68652 NXP Semiconductors, scn68652 Datasheet - Page 14

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

Philips Semiconductors
Table 6.
1995 May 01
Multi-protocol communications controller (MPCC)
00–07
08–10
BIT
11
12
13
14
15
Parameter Control SYNC/Address Register (PCSAR)–(R/W)
PROTO
NAME
SS/GA
S/AR
ECM
IDLE
SAM
APA
BOP/BCP
MODE
BOP
BOP
BOP
BOP
BOP
BOP
BCP
BCP
BCP
BCP
FUNCTION
SYNC/address register. Contains the secondary station address if the MPCC is a secondary
station. The contents of this register is compared with the first received non-FLAG character
to determine if the message is meant for this station.
SYNC character is loaded into this register by the processor. It is used for receive and
transmit bit synchronization with bit length specified by RxCL and TxCL.
Error Control Mode
CRC–CCITT preset to 1’s
CRC–CCITT preset to 0’s
Not used
CRC–16 preset to 0’s
VRC odd
VRC even
Not used
No error control
ECM should be loaded by the processor during initialization or when both data paths are idle.
Determines line fill character to be used if transmitter underrun occurs (TxU asserted and
TERR set) and transmission of special characters for BOP/BCP.
IDLE = 0, transmit ABORT characters during underrun and when TABORT = 1.
IDLE = 1, transmit FLAG characters during underrun and when TABORT = 1.
IDLE = 0 transmit initial SYNC characters and underrun line fill characters from theS/AR.
IDLE = 1 transmit initial SYNC characters from TxDB and marks TxSO during underrun.
Secondary Address Mode = 1 if the MPCC is a secondary station. This facilitates automatic
recognition of the received secondary station address. When transmitting, the processor must
load the secondary address into TxDB.
SAM = 0 inhibits the received secondary address comparison which serves to activate the
receiver after the first non-FLAG character has been received.
Strip SYNC/Go Ahead. Operation depends on mode.
SS/GA = 1 is used for loop mode only and enables GA detection. When a GA is detected as a
closing character, REOM and RAB/GA will be set and the processor should terminate the
repeater function. SS/GA = 0 is the normal mode which enables ABORT detection. It causes
the receiver to terminate the frame upon detection of an ABORT or FLAG.
SS/GA = 1, causes the receiver to strip SYNC’s immediately following the first two SYNC’s
detected. SYNC’s in the middle of a message will not be stripped. SS/GA = 0, presents any
SYNC’s after the initial two SYNC’s to the processor.
Determines MPCC Protocol mode
PROTO = 0
PROTO = 1
All parties address. If this bit is set, the receiver data path is enabled by an address field of
‘11111111’ as well as the normal secondary station address.
14
10
0
0
0
0
1
1
1
1
9
0
0
1
1
0
0
1
1
8
0
1
0
1
0
1
0
1
Suggested Mode
BCP/BOP
SCN2652/SCN68652
BOP
BCP
BCP
BCP
BCP
–––
–––
Char. length
Product specification
1–8
5–7
5–7
5–8
8
8