Boot Assist Module (BAM) RM0046
826/936 Doc ID 16912 Rev 5
Boot from FlexCAN with autobaud enabled
The only difference between booting from FlexCAN with autobaud enabled and booting from
FlexCAN with autobaud disabled is that the following initialization FlexCAN frame is sent for
baud measurement purposes from the host to the MCU when autobaud is enabled:
● Standard identifier = 0x0,
● Data Length Code (DLC) = 0x0.
As all the bits to be transmitted are dominant bits, there is a succession of 5 dominant bits
and 1 stuff bit on the FlexCAN network (see Figure 491).
From the duration of this frame, the MCU calculates the corresponding baud rate factor with
respect to the current CPU clock and initializes the FlexCAN interface accordingly.
Figure 491. Bit time measure
In FlexCAN boot mode, the FlexCAN RX pin is first configured to work as a GPIO input. In
the end of baud rate measurement, it switches to work with the FlexCAN module.
The baud rate measurement flow is detailed in Figure 492.
Measured Time
Start Shift bitShift bit Shift bit Shift bit
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