Freescale Semiconductor MPC5604B, Quick Start Manual

Page: 122 / 150

And the timer interrupt is at left; it transmits the
counter ‘myData’ and increments it. LEDs are altered to
alert the user.
The transmissions will be made with an ID equal to 666
and receptions will be expected from an ID of 555.
8.1. Initialisation
There are six major steps to initialising the FlexCAN module:
1. Initializing the MCR to meet the specifications & needs,
2. Initialize the CTRL to meet timing parameter specification and set arbitration,
3. Initialise the Message Buffers / FIFO (SRAM has to be cleared), set their control and
status words
4. Initialise ID filtering register (Individual Mask registers or the global mask registers
depending on MCR)
5. Configure interrupts and their masks
6. Negate the HALT bit in the MCR
Here’s this program’s FlexCAN initialisation procedure, where global ID filters are used (for
standard ID), no FIFO, only 8 MBs are ready of which only two are used.
8.2. Transmission
For starting the transmission process, prepare a message buffer by setting it at TX INACTIVE
mode (1000), this is done in the initialization code above. And then set as needed different fields
of the message buffer (IDE, DATA, LENGTH, RTR, ID etc.) but not the CODE. Setting the code to
1100 activates the MB.