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MC9S08DE60 Datasheet, PDF (226/412 Pages) Freescale Semiconductor, Inc – Microcontrollers | |||
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Chapter 12 Freescaleâs Controller Area Network (S08MSCANV1)
12.3.2 MSCAN Control Register 1 (CANCTL1)
The CANCTL1 register provides various control bits and handshake status information of the MSCAN
module as described below.
R
W
Reset:
7
CANE
0
6
CLKSRC
5
LOOPB
0
0
= Unimplemented
4
LISTEN
1
3
BORM
0
2
WUPM
0
1
SLPAK
0
0
INITAK
1
Figure 12-5. MSCAN Control Register 1(CANCTL1)
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).
Table 12-2. CANCTL1 Register Field Descriptions
Field
Description
7
CANE
6
CLKSRC
5
LOOPB
4
LISTEN
3
BORM
2
WUPM
MSCAN Enable
0 MSCAN module is disabled
1 MSCAN module is enabled
MSCAN Clock Source â This bit deï¬nes the clock source for the MSCAN module (only for systems with a clock
generation module; Section 12.5.3.3, âClock System,â and Section Figure 12-42., âMSCAN Clocking Scheme,â).
0 MSCAN clock source is the oscillator clock
1 MSCAN clock source is the bus clock
Loopback Self Test Mode â 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.Section 12.5.4.6, âLoopback Self Test Mode.
0 Loopback self test disabled
1 Loopback self test enabled
Listen Only Mode â This bit conï¬gures 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 12.5.4.4, âListen-Only Modeâ). In addition, the error counters are frozen. Listen only mode supports
applications which require âhot pluggingâ 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 â This bits conï¬gures the bus-off state recovery mode of the MSCAN. Refer to
Section 12.6.2, âBus-Off Recovery,â for details.
0 Automatic bus-off recovery (see Bosch CAN 2.0A/B protocol speciï¬cation)
1 Bus-off recovery upon user request
Wake-Up Mode â If WUPE in CANCTL0 is enabled, this bit deï¬nes whether the integrated low-pass ï¬lter is
applied to protect the MSCAN from spurious wake-up (see Section 12.5.5.4, âMSCAN Sleep Modeâ).
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 Twup
MC9S08DE60 Series Data Sheet, Rev. 3
226
Freescale Semiconductor
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