MPC555CME Freescale Semiconductor, MPC555CME Datasheet - Page 595

• Manufacturer Part Number: MPC555CME
• Description: KIT EVALUATION FOR MPC555
• Manufacturer: Freescale Semiconductor
• Type: Microcontrollerr

Specifications of MPC555CME

• Contents: Module Board, Installation Guide, Power Supply, Cable, Software and more
• Processor To Be Evaluated: MPC555
• Data Bus Width: 32 bit
• Interface Type: RS-232
• For Use With/related Products: MPC555
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

16.4.3.1 Transmit Message Buffer Deactivation
16.4.3.2 Reception of Transmitted Frames
16.4.4 Receive Process
MPC555
USER’S MANUAL
When this process is over and a message buffer is selected for transmission, the
frame from that message buffer is transferred to the serial message buffer for trans-
mission.
The TouCAN transmits no more than eight data bytes, even if the transmit length con-
tains a value greater than eight.
At the end of a successful transmission, the value of the free-running timer (which was
captured at the beginning of the identifier field on the CAN bus), is written into the time
stamp field in the message buffer. The code field in the control/status word of the mes-
sage buffer is updated and a status flag is set in the IFLAG register.
Any write access to the control/status word of a transmit message buffer during the
process of selecting a message buffer for transmission immediately deactivates that
message buffer, removing it from the transmission process.
If the user deactivates a transmit message buffer while a message is being transferred
from it to a serial message buffer, the message is not transmitted.
If the user deactivates the transmit message buffer after the message is transferred to
the serial message buffer, the message is transmitted, but no interrupt is requested,
and the transmit code is not updated.
If a message buffer containing the lowest ID is deactivated while that message is un-
dergoing the internal arbitration process to determine which message should be sent,
then that message may not be transmitted.
The TouCAN receives a frame it has transmitted if an empty message buffer with a
matching identifier exists.
During the receive process, the following events occur:
The user should prepare or change a message buffer for frame reception by executing
the following steps.
• The user configures the message buffers for reception
• The TouCAN transfers received messages from the serial message buffers to the
• The user retrieves these messages
1. Write the control/status word to hold the receive buffer inactive (code = 0b0000)
2. Write the ID_HIGH and ID_LOW words
3. Write the control/status word to mark the receive message buffer as active and
/
receive message buffers with matching IDs
MPC556
empty
Steps one and three are mandatory for data coherency.
CAN 2.0B CONTROLLER MODULE
Rev. 15 October 2000
NOTE
MOTOROLA
16-13