PRE1 PRE0 | Intel 8XC196Lx, 8XC196Jx, 8XC196Kx, 87C196CA manual

J1850 COMMUNICATIONS CONTROLLER

J_CFG	Address:	1F54H
	Reset State:	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

Bit

Function

Number

Mnemonic

2

—

Reserved; for compatibility with future devices, write zero to this bit.

1:0

PRE1:0

J1850 Oscillator Prescaler

These bits ensure proper operation of the J1850 peripheral at the supported

input frequencies (FXTAL1).

PRE1

PRE0

FXTAL1

0

0

8 MHz

0

1

12 MHz

1

0

16 MHz

1

1

20 MHz

Figure 8-17. J1850 Configuration (J_CFG) Register (Continued)

8.6.3Programming the J1850 Delay Compensation (J_DLY) Register

The J1850 delay compensation register (Figure 8-18) allows you to program the necessary delay time through the external transceiver to compensate for the inherent propagation delays and to accurately resolve bus contention during arbitration.

8-19

Image 85

Intel 8XC196Lx, 8XC196Jx, 8XC196Kx, 87C196CA user manual Programming the J1850 Delay Compensation Jdly Register, PRE1 PRE0

Contents

August Page Contents 8XC196LX Supplement Chapter Synchronous Serial I/O Port Functional Groupings of Signals Default Conditions Entering and Exiting Once ModeProgramming the J1850 Controller Internal Timing Figures 11-3 Tables Guide to This Manual Page Chapter Guide to this Manual Manual Contents Related Documents Related Documents Architectural Overview Page Features of the 8XC196Lx and 8XC196Kx Product Famiies Microcontroller FeaturesChapter Architectural Overview Internal Timing Block Diagram Clock Circuitry 87C196LA, LB Only MHz State Times at Various Frequencies12 MHz 16 MHz Pllen External TimingMultiplier State Time Uprom Programming Values and Locations Internal PeripheralsCLK1 CLK0 Synchronous Serial I/O Port 1 I/O PortsEvent Processor Array 4 J1850 Communications ControllerPage Address Space Page Address Partitions Chapter Address SpaceAddress Map 1BFF Register File CA,JT,KT AddressJR, KR XC196Lx Peripheral SFRs Peripheral SPECIAL-FUNCTION RegistersUSFR1 LA, LB SSIO0CLK SSIO1CLKRstsrc Jdly Windows Windowing Upper Register File CA, JT, JV, KT BaseUpper Register File CA, JT, JV, KT, LA, LB 0140H 4BH25H 0120H 49H 0100H 48H 24H 12H Standard and PTS Interrupts Page Interrupt SOURCES, VECTORS, and Priorities Chapter Standard and PTS Interrupts Interrupt Registers Interrupt Controller PTS ServiceInterrupt Sources, Vectors, and Priorities Interrupt Source Mnemonic Priority Name Intmask Interrupt Mask RegistersBit Function Number Bit Mnemonic Interrupt Description INTMASK1 Interrupt Pending RegistersLA, LD NMI Extint SSIO1 SSIO0 Intpend Interrupt Pending Intpend Register INTPEND1 Peripheral Transaction Server RegistersNMI Bit PtsselInterrupt PTS Vector Bits PtssrvInterrupt Standard Vector Ports Page I/O Ports Overview Chapter PortsMicrocontroller Ports EPA, Ssio 8XC196LX Supplement Ports 1, 2, 5, and 6 Internal Structure 87C196LA, LB Only Configuring Ports 1, 2, 5, and 6 Bidirectional Ports Special Bidirectional Port Considerations For complementary output configurations Internal Structure for Ports 3 and 4 ADDRESS/DATA BUS 8XC196L X Supplement Synchronous Serial Port Page Ssio 0 Clock Register Chapter Synchronous Serial I/O PortBit Function For receptions 1FB7H Ssio 1 Clock RegisterCHS DUP Conint Conpnd Phas Pols CHS SSIO1CLK Page Event Processor Array Page EPA Functional Overview Chapter Event Processor ArrayEPA Channels Device Capture/Compare Compare-only EPA Block Diagram 87C196LA, LB Only EPA Block Diagram 83C196LD Only Epamask EPA Mask RegistersEPAMASK1 Epapend EPA Pending RegistersEPAPEND1 Value Interrupt EPA Interrupt Priority Vector RegisterEpaipv J1850 Communications Controller Page J1850 Functional Overview J1850 Communications ControllerPLL Clkout J1850 Communications Controller Block Diagram J1850 Controller Signals J1850 Controller Signals and RegistersSignal Control and Status Registers Control State Machine J1850 Controller OperationCyclic Redundancy Check Generator Bus Contention Symbol Synchronization and Timing CircuitryError Detection Bit Arbitration Symbol Encoding and Decoding Delay CompensationClock Prescaler Digital Filter Bit Arbitration Example Huntzicker Symbol Definition for J1850 Bit Arbitration Example Message Frames Header Standard MessagingCRC Byte Normalization Bit 64µS 128µS NB for IFR with CRC NB for IFR without CRC Name Symbol Bus Level TXmin TXnom TXmax RXmin RXmax Units Huntzicker Symbol Timing Characteristics IFR Messaging Type 1 Single Byte, Single Responder In-frame Response Messaging Transmitting Messages Transmitting and Receiving Messages CPU JTX Jtxbuf Transmit Byte Receive Byte Receiving MessagesCPU Jrxbuf IFR Messages Programming the J1850 Command Jcmd RegisterProgramming the J1850 Controller Auto IFR Ignore Abort MSG3 MSG2 MSG1 MSG0 JcmdAuto MSG30 Operation Purpose NBF IFR3 4XM Txbrk Rxpol PRE1 PRE0 Programming the J1850 Configuration Jcfg RegisterNBF IFR without CRC Byte PRE1 PRE0 Programming the J1850 Delay Compensation Jdly Register 18. J1850 Delay Jdly Register Jstat Programming the J1850 Status Jstat Register Msgrx Msgtx Minimum Hardware Considerations Page Minimum Hardware Considerations Identifying the Reset Source Design Considerations for 8XC196LA, LB, and LD Special Operating Modes Page Chapter Special Operating Modes Entering and Exiting Once Mode 10-3 Page Programming Nonvolatile Memory Page Signature Word and Programming Voltage Values Programming the Nonvolatile MemoryOtprom Address MAP Signature Word and Programming Voltage Values C196LA, LB Otprom Address Map Slave Programming Circuit and Address MAPAddress Range Description Hex CCB1 Description Address Comments Serial Port Programming Circuit Serial Port Programming Circuit and Address MAP Description Address Range Serial Port Programming Mode Address MapA000-FFFFH Do not addressPage Signal Descriptions Page Functional Groupings of Signals Appendix a Signal Descriptions Table A-1 C196LA Signals Arranged by Functional Categories Signal Descriptions Table A-2 C196LB Signals Arranged by Functional Categories Figure A-2 C196LB 52-pin Plcc Package Input Name Pin Table A-3 C196LD Signals Arranged by Functional CategoriesInput/Output Cont’d Name Pin Bus Control & Status Default Conditions Port Alternate During RESET# Upon RESET# Power Table A-5 C196LA, LB Default Signal ConditionsSignals Functions Table A-6 C196LD Default Signal Conditions Page Glossary Page ALU GlossaryBIT Byte EPA DOUBLE-WORDESD Integer FET LONG-INTEGER ISRLSB LSW MSW MSB PIC PIH PLL PTS PSWPtscb Ralu QUAD-WORD SFR SARSHORT-INTEGER Uart WDT VPWWord Index Page Clkout Index Index-2