PIC18F258 MICROCHIP [Microchip Technology], PIC18F258 Datasheet - Page 227

• Manufacturer Part Number: PIC18F258
• Description: High Performance, 28/40-Pin Enhanced FLASH Microcontrollers with CAN
• Manufacturer: MICROCHIP [Microchip Technology]

FIGURE 19-3:
 2002 Microchip Technology Inc.
The TXIE bit determines if an inter-
rupt should be generated when a
message is successfully transmitted.
Generate
Interrupt
TRANSMIT MESSAGE FLOW CHART
Examine TXPRI <1:0> to
Determine Highest Priority Message
No
Yes
Begin Transmission (SOF)
Clear: TXABT, TXLARB
Message Transmitted
to Start Transmission
CAN bus Available
Set TXREQ = 0
Successfully?
and TXERR
TXBUFE = 1
TXIE = 1?
TXREQ
Are any
bits = 1
END
Start
Was
Set
Is
Is
?
?
Yes
Yes
Yes
No
A message can also be
aborted, if a message
error or lost arbitration
condition occurred during
transmission.
No
No
Preliminary
The message transmission sequence begins when
the device determines that the TXREQ for any of the
transmit registers has been set.
Clearing the TXREQ bit while it is set, or setting
the ABAT bit before the message has started
transmission, will abort the message.
TXLARB = 1?
or TXABT = 1
TXREQ = 0
TXREQ = 0
ABAT = 1
TXERR = 1
No
No
Set
Is
Is
?
Is
?
No
Yes
Yes
Yes
Abort Transmission:
Set TXABT = 1
PIC18FXX8
Arbitration Lost During
Transmission
DS41159B-page 225