J1850 Byte Level Protocol Decoder (JBLPD)
10.9 J1850 Byte Level Protocol Decoder (JBLPD)
10.9.1 Introduction
10.9.2 Main Features
■ SAE J1850 compatible
■ Digital filter
The JBLPD is used to exchange data between the
ST9 microcontroller and an external J1850 trans-
ceiver I.C.
■ In-Frame Responses of type 0, 1, 2, 3 supported
The JBLPD transmits a string of variable pulse
width (VPW) symbols to the transceiver. It also re-
ceives VPW encoded symbols from the transceiv-
er, decodes them and places the data in a register.
with automatic normalization bit
■ Programmable External Loop Delay
■ Diagnostic 4x time mode
■ Diagnostic Local Loopback mode
In-frame responses of type 0, 1, 2 and 3 are sup-
ported and the appropriate normalization bit is
generated automatically. The JBLPD filters out
any incoming messages which it does not care to
receive. It also includes a programmable external
loop delay.
■ Wide range of MCU internal frequencies
allowed
■ Low power consumption mode (JBLPD
suspended)
■ Very low power consumption mode (JBLPD
disabled)
■ Don’t care message filter
The JBLPD uses two signals to communicate with
the transceiver:
– VPWI (input)
■ Selectable VPWI input polarity
■ Selectable Normalization Bit symbol form
■ 6 maskable interrupts
– VPWO (output)
■ DMA transmission and reception with End Of
Block interrupts
283/426
9
STMICROELECTRONICS [ ST ]
