Intel 87C196CB Manual De Usuario

7-24

Address:
Reset State:

1E

x

0H (

x

 = 1–F)

Unchanged

Program the CAN message object 

x

 control 0 (CAN_MSG

x

CON0) register to indicate whether the 

message object is ready to transmit and to control whether a successful transmission or reception 
generates an interrupt. The least-significant bit-pair indicates whether an interrupt is pending.

This register consists of four bit-pairs — the most-significant bit of each pair is in true form and the 
least-significant bit is in complement form. This format allows software to set or clear any bit with a 
single write operation, without affecting the remaining bits.

MSGVAL

MSGVAL

TXIE

TXIE

RXIE

RXIE

INT_PND

INT_PND

7:6

MSGVAL

Message Object Valid

Set this bit-pair to indicate that a message object is valid (configured and 
ready for transmission or reception).

0

1

not ready

1

0

message object is valid

The CAN peripheral will access a message object only if this bit-pair 
indicates that the message is valid. If multiple message objects have the 
same identifier, only one can be valid at any given time.

During initialization, software should clear this bit for any unused message 
objects. Software can clear this bit if a message is no longer needed or if 
you need to change a message object’s contents or identifier.

5:4

TXIE

Transmit Interrupt Enable

Receive message objects do not use this bit-pair.

For transmit message objects, set this bit-pair to enable the CAN 
peripheral to initiate a transmit (TX) interrupt after a successful trans-
mission. You must also set the interrupt enable bit (CAN_CON.1) to enable 
the interrupt.

0

1

no interrupt

1

0

generate an interrupt