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Chapter 14 Freescale’s Scalable Controller Area Network (S12MSCANV3)
MC9S12XDP512 Data Sheet, Rev. 2.11
618 Freescale Semiconductor
14.1.2 Block Diagram
Figure 14-1. MSCAN Block Diagram
14.1.3 Features
The basic features of the MSCAN are as follows:
• Implementation of the CAN protocol — Version 2.0A/B
— Standard and extended data frames
— Zero to eight bytes data length
— Programmable bit rate up to 1 Mbps
1
— Support for remote frames
• Five receive buffers with FIFO storage scheme
• Three transmit buffers with internal prioritization using a “local priority” concept
• Flexible maskable identifier filter supports two full-size (32-bit) extended identifier filters, or four
16-bit filters, or eight 8-bit filters
• Programmable wakeup functionality with integrated low-pass filter
• Programmable loopback mode supports self-test operation
• Programmable listen-only mode for monitoring of CAN bus
• Programmable bus-off recovery functionality
• Separate signalling and interrupt capabilities for all CAN receiver and transmitter error states
(warning, error passive, bus-off)
• Programmable MSCAN clock source either bus clock or oscillator clock
• Internal timer for time-stamping of received and transmitted messages
1. Depending on the actual bit timing and the clock jitter of the PLL.
RXCAN
TXCAN
Receive/
Transmit
Engine
Message
Filtering
and
Buffering
Control
and
Status
Wake-Up Interrupt Req.
Errors Interrupt Req.
Receive Interrupt Req.
Transmit Interrupt Req.
CANCLK
Bus Clock
Configuration
Oscillator Clock
MUX
Presc.
Tq Clk
MSCAN
Low Pass Filter
Wake-Up
Registers