mc9s12xd256 Freescale Semiconductor, Inc, mc9s12xd256 Datasheet - Page 427

• Manufacturer Part Number: mc9s12xd256
• Description: Hcs12x Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Read: Anytime
Write: Anytime when INITRQ = 1 and INITAK = 1, except CANE which is write once in normal and
anytime in special system operation modes when the MSCAN is in initialization mode (INITRQ = 1 and
INITAK = 1).
Freescale Semiconductor
CLKSRC
LISTEN
LOOPB
WUPM
BORM
CANE
Field
7
6
5
4
3
2
Reset:
W
R
MSCAN Enable
0 MSCAN module is disabled
1 MSCAN module is enabled
MSCAN Clock Source — This bit defines the clock source for the MSCAN module (only for systems with a clock
generation module;
0 MSCAN clock source is the oscillator clock
1 MSCAN clock source is the bus clock
Loopback Self Test Mode — When this bit is set, the MSCAN performs an internal loopback which can be used
for self test operation. The bit stream output of the transmitter is fed back to the receiver internally. The RXCAN
input pin is ignored and the TXCAN output goes to the recessive state (logic 1). The MSCAN behaves as it does
normally when transmitting and treats its own transmitted message as a message received from a remote node.
In this state, the MSCAN ignores the bit sent during the ACK slot in the CAN frame acknowledge field to ensure
proper reception of its own message. Both transmit and receive interrupts are generated.
0 Loopback self test disabled
1 Loopback self test enabled
Listen Only Mode — This bit configures the MSCAN as a CAN bus monitor. When LISTEN is set, all valid CAN
messages with matching ID are received, but no acknowledgement or error frames are sent out (see
Section 10.4.4.4, “Listen-Only
applications which require “hot plugging” or throughput analysis. The MSCAN is unable to transmit any
messages when listen only mode is active.
0 Normal operation
1 Listen only mode activated
Bus-Off Recovery Mode — This bits configures the bus-off state recovery mode of the MSCAN. Refer to
Section 10.5.2, “Bus-Off
0 Automatic bus-off recovery (see Bosch CAN 2.0A/B protocol specification)
1 Bus-off recovery upon user request
Wake-Up Mode — If WUPE in CANCTL0 is enabled, this bit defines whether the integrated low-pass filter is
applied to protect the MSCAN from spurious wake-up (see
0 MSCAN wakes up on any dominant level on the CAN bus
1 MSCAN wakes up only in case of a dominant pulse on the CAN bus that has a length of T
CANE
0
7
= Unimplemented
CLKSRC
Figure 10-5. MSCAN Control Register 1 (CANCTL1)
Table 10-2. CANCTL1 Register Field Descriptions
0
6
Section 10.4.3.2, “Clock
Recovery,” for details.
MC9S12XDP512 Data Sheet, Rev. 2.17
LOOPB
Mode”). In addition, the error counters are frozen. Listen only mode supports
0
5
Chapter 10 Freescale’s Scalable Controller Area Network (S12MSCANV3)
LISTEN
System,” and
1
4
Description
Section Figure 10-43., “MSCAN Clocking
BORM
Section 10.4.5.4, “MSCAN Sleep
3
0
WUPM
0
2
SLPAK
0
1
wup
Mode”).
Scheme,”).
INITAK
1
0
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