MPC5604B/C Microcontroller Reference Manual, Rev. 8
Freescale Semiconductor 253
Chapter 14
CAN Sampler
14.1 Introduction
The CAN sampler peripheral has been designed to store the first identifier of CAN message “detected” on
the CAN bus while no precise clock (crystal) is running at that time on the device, typically in low power
modes (STOP, HALT or STANDBY) or in RUN mode with crystal switched off.
Depending on both CAN baud rate and low power mode used, it is possible to catch either the first or the
second CAN frame by sampling one CAN Rx port among six and storing all samples in internal registers.
After selection of the mode (first or second frame), the CAN sampler stores samples of the 48 bits or skips
the first frame and stores samples of the 48 bits of second frame using the 16 MHz fast internal RC
oscillator and the 5-bit clock prescaler.
After completion, software has to process the sampled data in order to rebuild the 48 minimal bits.
Figure 14-1. Extended CAN data frame
14.2 Main features
• Store 384 samples, equivalent to 48 CAN bit @ 8 samples/bit
• Sample frequency from 500 kHz up to 16 MHz, equivalent at 8 samples/bit to CAN baud rates of
62.5 Kbps to 2 Mbps
• User selectable CAN Rx sample port [CAN0RX-CAN5RX]
• 16 MHz fast internal RC oscillator clock
• 5-bit clock prescaler
• Configurable trigger mode (immediate, next frame)
• Flexible samples processing by software
• Very low power consumption
Base Identifier (11-bit)
SOF
SPR
Extended Identifier (18-bit)
IDE-bit
RTR-bit
r1
r0
Data
Length
Code
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