CAN 2.0B Controller Module
MPC561/MPC563 Reference Manual, Rev. 1.2
Freescale Semiconductor
16-13
Following the negation of reset, the TouCAN is not synchronized with the CAN bus, and the HALT, FRZ,
and FRZACK bits in the module configuration register are set. In this state, the TouCAN does not initiate
frame transmissions or receive any frames from the CAN bus. The contents of the message buffers are not
changed following reset.
Any configuration change or initialization requires that the TouCAN be frozen by either the assertion of
the HALT bit in the module configuration register or by reset.
16.4.2
TouCAN Initialization
Initialization of the TouCAN includes the initial configuration of the message buffers and configuration of
the CAN communication parameters following a reset, as well as any reconfiguration which may be
required during operation. The following is a general initialization sequence for the TouCAN:
1. Initialize all operation modes
a) Initialize the transmit and receive pin modes in CANCTRL0
b) Initialize the bit timing parameters PROPSEG, PSEGS1, PSEG2, and RJW in CANCTRL1 and
CANCTRL2
c) Select the S-clock rate by programming the PRESDIV register
d) Select the internal arbitration mode (LBUF bit in CANCTRL1)
2. Initialize message buffers
a) The control/status word of all message buffers must be written either as an active or inactive
message buffer.
b) All other entries in each message buffer should be initialized as required
3. Initialize mask registers for acceptance mask as required
4. Initialize TouCAN interrupt handler
a) Initialize the interrupt configuration register (CANICR) with a specific request level
b) Set the required mask bits in the IMASK register (for all message buffer interrupts), in
CANCTRL0 (for bus off and error interrupts), and in CANMCR for the WAKE interrupt
5. Negate the HALT bit in the module configuration register. At this point, the TouCAN attempts to
synchronize with the CAN bus
NOTE
In both the transmit and receive processes, the first action in preparing a
message buffer must be to deactivate the buffer by setting its code field to
the proper value. This step is mandatory to ensure data coherency.
16.4.3
Transmit Process
The transmit process includes preparation of a message buffer for transmission, as well as the internal steps
performed by the TouCAN to decide which message to transmit. This involves loading the message and
ID to be transmitted into a message buffer and then activating that buffer as an active transmit buffer. Once
this is done, the TouCAN performs all additional steps necessary to transmit the message onto the CAN
bus.
Summary of Contents for MPC561
Page 84: ...MPC561 MPC563 Reference Manual Rev 1 2 lxxxiv Freescale Semiconductor...
Page 144: ...Signal Descriptions MPC561 MPC563 Reference Manual Rev 1 2 2 46 Freescale Semiconductor...
Page 206: ...Central Processing Unit MPC561 MPC563 Reference Manual Rev 1 2 3 62 Freescale Semiconductor...
Page 302: ...Reset MPC561 MPC563 Reference Manual Rev 1 2 7 14 Freescale Semiconductor...
Page 854: ...Time Processor Unit 3 MPC561 MPC563 Reference Manual Rev 1 2 19 24 Freescale Semiconductor...
Page 968: ...Development Support MPC561 MPC563 Reference Manual Rev 1 2 23 54 Freescale Semiconductor...
Page 1144: ...Internal Memory Map MPC561 MPC563 Reference Manual Rev 1 2 B 34 Freescale Semiconductor...
Page 1212: ...TPU3 ROM Functions MPC561 MPC563 Reference Manual Rev 1 2 D 60 Freescale Semiconductor...
Page 1216: ...Memory Access Timing MPC561 MPC563 Reference Manual Rev 1 2 E 4 Freescale Semiconductor...