RM0046 Boot Assist Module (BAM)
Doc ID 16912 Rev 5 821/936
After setting up the system clock, the BAM autoscan code configures the FlexCAN RX pin
(B[1] on all packages) and LINFlex RX pin (B[3] on LQFP100 or B[7] on LQFP64) as GPIO
inputs and searches for FlexCAN RX pin level to verify if CAN is connected or not.
Then continuously waits in polling on change of RX pins level.The FlexCAN RX pin level
takes precedence. First signal found at low level selects the serial boot routine that will be
executed.
In case a low level is detected on any input, the corresponding autobaud measurement
functionality is started:
● when FlexCAN RX (corresponds to pin B[1]) level is low, the CAN autobaud
measurement starts and then sets up the FlexCAN baud rate accordingly;
● when UART RX (corresponds to pin B[3] on LQFP100 or B[7] on LQFP64) level is low,
the UART autobaud measurement starts and then sets up the LINFlex baud rate
accordingly.
After performing the autobaud measurement and setting up the baud rate, the
corresponding RX input is reconfigured and the related standard download process is
started; in case of a detected CAN transmission a download using the CAN protocol as
described in section Section 33.5.7, “Bootstrap with FlexCAN—autobaud disabled, and in
case of a detected UART transmission a download using the UART protocol as described in
Section 33.5.6, “Boot from UART—autobaud disabled.
The following Figure 487 identifies the corresponding flow and steps.
Note: When autobaud scan is selected, initially both LINFlex_0 RX pin and FlexCAN_0 RX pin
should be at high level. No external circuity should pull-down them to allow right autoscan.
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