PXD10RM Datasheet, PDF (173/1332 Pages) Freescale Semiconductor, Inc – PXD10 Microcontroller

Chapter 7
CAN Sampler
7.1 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 baudrate and Low Power mode used, it is possible to catch either the first or the
second CAN frame by sampling one of two CAN Rx ports 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 IRC oscillator and the
5-bit clock prescaler.
After completion, Software has to process the sampled data in order to rebuild the 48 minimal bits.
Base Identifier (11 bit)
SPR
SOF
Extended Identifier (18 bit)
IDE-bit
RTR-bit
r1
Data
Length
Code
r0
Figure 7-1. Extended CAN data frame
PXD10 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor
7-1
Preliminary—Subject to Change Without Notice