Intel 8XC196K Series User Manual page 548

Table of Contents

CAN_MSG x CON1 (Continued)

x = 1–15 (87C196CA)

The CAN message object x control 1 (CAN_MSG x CON1) register indicates whether a message

object has been updated, whether a message has been overwritten, whether the CPU is updating the

message, and whether a transmission or reception 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.

Table C-6. CAN_MSG x CON1 Addresses and Reset Values

CAN_MSG1CON1

CAN_MSG2CON1

CAN_MSG3CON1

CAN_MSG4CON1

CAN_MSG5CON1

CAN_MSG6CON1

CAN_MSG7CON1

CAN_MSG8CON1

After reset, this register contains the value that was written to it before reset.

This bit-pair indicates whether a message object is valid (configured and

ready for transmission).

message object is valid

For receive message objects, the CAN peripheral sets this bit-pair when it

stores new data into the message object.

For transmit message objects, set this bit-pair and clear the CPUUPD bit-

pair to indicate that the message contents have been updated. Clearing

CPUUPD prevents a remote frame from triggering a transmission that

would contain invalid data.

During initialization, clear this bit for any unused message objects.

Reset State:

CAN_MSG9CON1

CAN_MSG10CON1

CAN_MSG11CON1

CAN_MSG12CON1

CAN_MSG13CON1

CAN_MSG14CON1

CAN_MSG15CON1

CAN_MSGxCON1