Microchip Technology DM164134 Data Sheet

© 2006 Microchip Technology Inc.

DS41159E-page 229

Start

Is CAN bus

Available to Start

Transmission?

No

Examine TXPRI <1:0> to

Are any

TXREQ 
bits = 1?

The message transmission sequence begins when
the device determines that the TXREQ for any of the
transmit registers has been set.

Clear: TXABT, TXLARB 

and TXERR

Yes

Is

TXREQ = 0

ABAT = 1? 

Clearing the TXREQ bit while it is set, or setting
the ABAT bit before the message has started
transmission, will abort the message.

No

Begin Transmission (SOF)

Abort Transmission:

Was

Message Transmitted

Successfully?

No

Yes

Set TXREQ = 0

Is

TXIE = 1?

Generate 

Interrupt

Yes

Yes

Set TXABT = 1

Set

Set 

TXERR = 1

Yes

No

Determine Highest Priority Message

No

Is 

TXLARB = 1?

The TXIE bit determines if an inter-
rupt should be generated when a
message is successfully transmitted.

END

Is

TXREQ = 0

or TXABT = 1?

Yes

No

TXBUFE = 1

Yes

A message can also be
aborted if a message
error or lost arbitration
condition occurred during
transmission.

Arbitration Lost During

Transmission

No