MCF5253VM140J Freescale Semiconductor, MCF5253VM140J Datasheet - Page 642

• Manufacturer Part Number: MCF5253VM140J
• Description: IC MCU 2.1MIPS 140MHZ 225MAPBGA
• Manufacturer: Freescale Semiconductor
• Series: MCF525xr

Specifications of MCF5253VM140J

• Core Processor: Coldfire V2
• Core Size: 32-Bit
• Speed: 140MHz
• Connectivity: CAN, EBI/EMI, I²C, QSPI, UART/USART, USB OTG
• Peripherals: DMA, WDT
• Program Memory Type: ROMless
• Ram Size: 128K x 8
• Voltage - Supply (vcc/vdd): 1.08 V ~ 1.32 V
• Data Converters: A/D 6x12b
• Oscillator Type: External
• Operating Temperature: -20°C ~ 70°C
• Package / Case: 225-MAPBGA
• Processor Series: MCF525x
• Core: ColdFire V2
• 3rd Party Development Tools: JLINK-CF-BDM26, EWCF
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Number Of I /o: -
• Eeprom Size: -
• Program Memory Size: -
• Lead Free Status / Rohs Status: Details

FlexCAN Module
Polling the control/status word of a receive message buffer can lock it, preventing a message from being
transferred into that buffer. If the control/status word of a receive message buffer is read, it should then be
followed by a read of the control/status word of another buffer, or by reading the free-running timer, to
ensure that the locked buffer is unlocked.
25.6.6
25.6.6.1
The remote frame is a message frame that is transmitted to request a data frame. The FlexCAN can be
configured to transmit a data frame automatically in response to a remote frame, or to transmit a remote
frame and then wait for the responding data frame to be received.
When transmitting a remote frame, the user initializes a message buffer as a transmit message buffer with
the RTR bit set. Once this remote frame is transmitted successfully, the transmit message buffer
automatically becomes a receive message buffer, with the same ID as the remote frame that was
transmitted.
When a remote frame is received by the FlexCAN, the remote frame ID is compared to the IDs of all
transmit message buffers programmed with a CODE of 1010. If there is an exact matching ID, the data
frame in that message buffer is transmitted. If the RTR bit in the matching transmit message buffer is set,
the FlexCAN will transmit a remote frame as a response.
A received remote frame is not stored in a receive message buffer. It is only used to trigger the automatic
transmission of a frame in response. The mask registers are not used in remote frame ID matching. All ID
bits (except RTR) of the incoming received frame must match for the remote frame to trigger a response
transmission. The matching message buffer immediately enters the internal arbitration process, but is
considered as a normal Tx MB, with no higher priority. The data length of this frame is independent of the
data length code (DLC) field in the remote frame that initiated its transmission.
25.6.6.2
Overload frame transmissions are not initiated by the FlexCAN unless certain conditions are detected on
the CAN bus. These conditions include detection of a dominant bit in the following:
25-26
6. If the user reads the control/status word of a receive message buffer while a frame is being
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transferred from a serial message buffer, the BUSY code will be indicated. The user should wait
until this code is cleared before continuing to read from the message buffer to ensure data
coherency. In this situation, the read of the control/status word will not lock the message buffer.
First or second bit of intermission
Seventh (last) bit of the end-of-frame (EOF) field in receive frames
CAN Protocol Related Frames
Remote Frames
Overload Frames
Deactivation takes precedence over locking. If the CPU deactivates a locked
Rx MB, then its lock status is negated, and the MB is marked as invalid for
the current matching round. Any pending message on the SMB will not be
transferred to the MB anymore.
MCF5253 Reference Manual, Rev. 1
NOTE
Freescale Semiconductor