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87C196CB SUPPLEMENT
7-14
1 IE Interrupt Enable
This bit globally enables and disables interrupts (error, status-change, and
message object transmit and receive interrupts).
0 = disable interrupts
1 = enable interrupts
When the IE bit is set, an interrupt is generated only if the corresponding
interrupt source’s enable bit (EIE or SIE in CAN_CON; TXIE or RXIE in
CAN_MSG
x
_CON0) is also set. If the IE bit is clear, an interrupt request
updates the CAN interrupt pending register, but does not generate an
interrupt.
0 INIT Software Initialization Enable
Setting this bit isolates the CAN bus from the system. (If a transfer is in
progress, it completes, but no additional transfers are allowed.)
0 = software initialization disabled
1 = software initialization enabled
A hardware reset sets this bit, enabling you to configure the RAM without
allowing any CAN bus activity. After a hardware reset or software initial-
ization, clearing this bit completes the initialization. The CAN peripheral
waits for a bus idle state (11 consecutive recessive bits) before partici-
pating in bus activities.
Software can set this bit to stop all receptions and transmissions on the
CAN bus. (To prevent transmission of a specific message object while its
contents are being updated, set the CPUUPD bit in the individual message
object’s control register 1. See “Configuring Message Objects” on page
7-20.)
Entering powerdown mode stops an in-progress CAN transmission
immediately. To avoid stopping a CAN transmission while it is sending a
dominant bit on the CAN bus, set the INIT bit before executing the IDLPD
instruction.
The CAN peripheral also sets this bit to isolate the CAN bus when an error
counter reaches 256. This isolation is called a
bus-off
condition. After a
bus-off condition, clearing this bit initiates a bus-off recovery sequence,
which clears the error counters. The CAN peripheral waits for 128 bus idle
states (128 packets of 11 consecutive recessive bits), then resumes
normal operation. (See “Bus-off State” on page 7-41.)
CAN_CON (Continued)
(87C196CB)
Address:
Reset State:
1E00H
01H
Program the CAN control (CAN_CON) register to control write access to the bit timing registers, to
enable and disable CAN interrupts, and to control access to the CAN bus.
7 0
87C196CB
— CCE — — EIE SIE IE INIT
Bit
Number
Bit
Mnemonic
Function
Figure 7-6. CAN Control (CAN_CON) Register (Continued)