8XC196L
X SUPPLEMENT
8-18
8.6.2
Programming the J1850 Configuration (J_CFG) Register
The J1850 configuration register (Figure 8-17) selects the proper oscillator prescaler, initiates a
transmission break for debugging, invokes clock quadrupling operation, and selects the normal-
ization bit format.
J_CFG
Address:
Reset State:
1F54H
00H
The J1850 configuration (J_CFG) register selects the proper oscilator prescaler, initiates transmission
break for debug, invokes clock quadrupling operation, and selects the normalizartion bit format. This
byte register can be directly addressed through
windowing. All J1850 bus activity is ignored until you
first write to this register.
7
0
NBF
IFR3
4XM
TXBRK
RXPOL
—
PRE1
PRE0
Bit
Number
Bit
Mnemonic
Function
7
NBF
Normalization Bit Format
This bit specifies which normalization bit (NB) format is to be used.
IFR with CRC Byte
IFR without CRC Byte
0 =
active long NB
0 =
active short NB
1 =
active short NB
1 =
active long NB
6
IFR3
Type 3 IFR Messaging
This bit selects type 3 IFR messaging, which supports the in-frame transfer
of an unspecified number of data bytes.
0 = normal operation
1 = type 3 IFR messaging
5
4XM
Oscillator Quadruple (4x) Mode
This bit allows the J1850 peripheral to operate at four times the normal bit
transfer rate (41.6 Kb/s versus 10.4 Kb/s).
0 = normal operation
1 = 4x mode operation
4
TXBRK
Transmission Break
This bit will terminate any transmission in progress by writing a break (BRK)
symbol to the bus.
0 = normal operation
1 = transmit BRK symbol onto bus
3
RXPOL
Receive Polarity
This bit changes the polarity of the receive symbol.
0 = normal operation – Rx input inverted
1 = receive polarity enabled – Rx input non-inverted
Figure 8-17. J1850 Configuration (J_CFG) Register
Содержание 87C196CA
Страница 1: ...8XC196Lx Supplement to 8XC196Kx 8XC196Jx 87C196CA User s Manual August 2004 Order Number 272973 003...
Страница 9: ...1 Guide to This Manual...
Страница 10: ......
Страница 13: ...2 Architectural Overview...
Страница 14: ......
Страница 22: ......
Страница 23: ...3 Address Space...
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Страница 33: ...4 Standard and PTS Interrupts...
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Страница 43: ...5 I O Ports...
Страница 44: ......
Страница 51: ...6 Synchronous Serial I O Port...
Страница 52: ......
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Страница 57: ...7 Event Processor Array...
Страница 58: ......
Страница 65: ...8 J1850 Communications Controller...
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Страница 89: ...9 Minimum Hardware Considerations...
Страница 90: ......
Страница 93: ...10 Special Operating Modes...
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Страница 99: ...11 Programming the Nonvolatile Memory...
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Страница 106: ......
Страница 107: ...A Signal Descriptions...
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Страница 119: ...Glossary...
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Страница 133: ...Index...
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