msCAN08 Controller (msCAN08)
MC68HC08AZ32
366
msCAN08 Controller (msCAN08)
MOTOROLA
To protect the CAN bus system from fatal consequences of violations to
the above rule, the msCAN08 will drive the TxCAN pin into recessive
state.
CPU WAIT mode
The msCAN08 module remains active during CPU WAIT mode. The
msCAN08 will stay synchronized to the CAN bus and will generate
enabled transmit, receive and error interrupts to the CPU. Any such
interrupt will bring the MCU out of WAIT mode.
Programmable
wake-up function
The msCAN08 can be programmed to apply a low-pass filter function to
the RxCAN input line while in internal sleep mode (see control bit WUPM
in
msCAN08 module control register (CMCR1)
on page 379). This
feature can be used to protect the msCAN08 from wake-up due to short
glitches on the CAN bus lines. Such glitches can result from
electromagnetic inference within noisy environments.
Timer link
The msCAN08 will generate a timer signal whenever a valid frame has
been received. Because the CAN specification defines a frame to be
valid if no errors occurred before the EOF field has been transmitted
successfully, the timer signal will be generated right after the EOF. A
pulse of one bit time is generated. As the msCAN08 receiver engine
receives also the frames being sent by itself, a timer signal will also be
generated after a successful transmission.
The previously described timer signal can be routed into the on-chip
Timer Interface Module (TIM). Under the control of the Timer Link
Enable (TLNKEN) bit in the CMCR0 will this signal be connected to the
Timer n Channel m input
1
.
After Timer n has been programmed to capture rising edge events it can
be used to generate 16-bit time stamps which can be stored under
software control with the received message.
1. The timer channel being used for the timer link is integration dependent.
20-can