AN1212 Freescale Semiconductor / Motorola, AN1212 Datasheet - Page 21

• Manufacturer Part Number: AN1212
• Description: J1850 Multiplex Bus Communication Using the MC68HC705C8 and the SC371016 J1850 Communications Interface (JCI)
• Manufacturer: Freescale Semiconductor / Motorola

MOTOROLA
CURRENT STATUS OF JCI
CLEAR "message to Tx"
BEGINNING AT "txbuf"
ROUTINE TO CHECK
LOAD BYTE COUNT
BEGIN TRANSMIT
LOCATION "txcntrl"
AND DATA BYTES
BIT IN MCU RAM
INTO MCU RAM,
CALL TXSTATUS
INTO MCU RAM
LOAD HEADER
TO PREVENT
INTERRUPTS
SEQUENCE
LOCATION
SET I BIT
"txcount"
J1850 Multiplex Bus Communication Using the MC68HC705C8
and the SC371016 J1850 Communications Interface (JCI)
Figure 11. Example Transmit Sequence
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
CALL TXDATA ROUTINE
CLEAR I BIT TO ALLOW
COMPARE INTERRUPT
TO TRANSFER FRAME
COMPARE BY VALUE
ADVANCE OUTPUT
END OF TRANSMIT
3-BYTE MESSAGE
ENABLE OUTPUT
(SEE
BYTES TO JCI
INTERRUPTS
complete" BIT
EQUAL TO A
SEQUENCE
"previous Tx
YES
SET?
Figure
IS
12)
NO
MC68HC705C8/JCI Interface Driver Routines
CLEAR I BIT TO ALLOW
SET "message to Tx"
RAM LOCATION
INTERRUPTS
BIT IN MCU
"txcntrl"
AN1212/D
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