8XC196LX SUPPLEMENT

The J1850 controller can handle network protocol functions including message frame sequenc- ing, bit arbitration, in-frame response (IFR) messaging, error detection, and delay compensation.

The J1850 communications controller (Figure 8-2) consists of a control state machine (CSM), symbol synchronization and timing (SST) circuitry, six control and status registers, transmit and receive buffers, and an interrupt handler.

J1850ST

 

Bus Error

J1850 Communications Controller

 

 

 

 

 

J1850RX

Interrupt

RX

 

 

 

J1850TX

Handler

TX

 

 

 

 

 

 

 

 

J_DLY

 

 

 

 

 

J_STAT

 

 

 

 

OVR

 

Error

 

 

 

 

Detection

 

 

 

UNDR

 

 

 

Circuitry

 

 

 

Bus

J_TX

 

 

 

 

 

 

 

Delay

 

Data

 

 

Symbol

Compensator

TXJ1850

 

 

 

JTX_BUF

Bit

Encoder

 

Peripheral

 

 

Arbitration

 

 

 

 

Symbol

 

 

JRX_BUF

Circuitry

Digital

 

Decoder

 

 

 

Filter

 

 

Cyclic

 

RXJ1850

 

 

 

 

 

 

 

 

 

Redundancy

 

 

 

 

J_RX

Check Circuitry

Prescaler

 

 

 

J_CMD

CSM

 

SST

 

 

 

 

 

 

 

J_CFG

 

 

 

 

Internal Clocking

 

 

 

 

 

 

 

 

 

 

A5169-01

Figure 8-2. J1850 Communications Controller Block Diagram

8-2

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Intel 8XC196Jx, 8XC196Lx, 8XC196Kx, 87C196CA user manual J1850 Communications Controller Block Diagram