mcf51ac256a Freescale Semiconductor, Inc, mcf51ac256a Datasheet - Page 320

• Manufacturer Part Number: mcf51ac256a
• Description: Mcf51ac Flexis
• Manufacturer: Freescale Semiconductor, Inc

Freescale’s Controller Area Network (MSCANV1)
Read: Anytime
Write: Anytime when out of initialization mode; exceptions are read-only RXACT and SYNCH, RXFRM
(which is set by the module only), and INITRQ (which is also writable in initialization mode).
15-4
RXFRM
CSWAI
SYNCH
RXACT
Field
TIME
7
6
5
4
3
Reset:
3
1
W
R
Received Frame Flag — This bit is read and clear only. It is set when a receiver has received a valid message
correctly, independently of the filter configuration. After it is set, it remains set until cleared by software or reset.
Clearing is done by writing a 1. Writing a 0 is ignored. This bit is not valid in loopback mode.
0 No valid message was received since last clearing this flag
1 A valid message was received since last clearing of this flag
Receiver Active Status — This read-only flag indicates the MSCAN is receiving a message. The flag is
controlled by the receiver front end. This bit is not valid in loopback mode.
0 MSCAN is transmitting or idle
1 MSCAN is receiving a message (including when arbitration is lost)
CAN Stops in Wait Mode — Enabling this bit allows for lower power consumption in wait mode by disabling all
the clocks at the CPU bus interface to the MSCAN module.
0 The module is not affected during wait mode
1 The module ceases to be clocked during wait mode
Synchronized Status — This read-only flag indicates whether the MSCAN is synchronized to the CAN bus and
able to participate in the communication process. It is set and cleared by the MSCAN.
0 MSCAN is not synchronized to the CAN bus
1 MSCAN is synchronized to the CAN bus
Timer Enable — This bit activates an internal 16-bit wide free running timer which is clocked by the bit clock rate.
If the timer is enabled, a 16-bit time stamp will be assigned to each transmitted/received message within the
active TX/RX buffer. As soon as a message is acknowledged on the CAN bus, the time stamp will be written to
the highest bytes (0x000E, 0x000F) in the appropriate buffer (see
Message
mode.
0 Disable internal MSCAN timer
1 Enable internal MSCAN timer
RXFRM
The CANCTL0 register, except WUPE, INITRQ, and SLPRQ, is held in the
reset state when the initialization mode is active (INITRQ = 1 and
INITAK = 1). This register is writable again as soon as the initialization
mode is exited (INITRQ = 0 and INITAK = 0).
0
7
MCF51AC256 ColdFire Integrated Microcontroller Reference Manual, Rev. 5
Storage”). The internal timer is reset (all bits set to 0) when disabled. This bit is held low in initialization
= Unimplemented
RXACT
Figure 15-3. MSCAN Control Register 0 (CANCTL0)
Table 15-1. CANCTL0 Register Field Descriptions
6
0
CSWAI
2
0
5
NOTE
SYNCH
4
0
Description
TIME
0
3
Section 15.4, “Programmer’s Model of
2
WUPE
2
0
Freescale Semiconductor
SLPRQ
0
1
INITRQ
0
1