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Chapter 33 Boot Assist Module (BAM)
MPC5602P Microcontroller Reference Manual, Rev. 4
834
Freescale Semiconductor
Initially the UART RX pin is configured as GPIO input and it waits in polling for the first falling edge,
then STM starts. UART RX pin waits again for the first rising. Then STM stops and from its measurement
baud rate is computed.
The LINFlex module is configured to work in UART mode with the calculated baud rate. Then an
acknowledge byte (0x59, ASCII char “Y”) is sent.
From this point, the BAM follows the normal UART mode boot protocol (see
).
Figure 33-11. BAM rate measurement flow during UART boot
Start
UART_RX == 0
NO
NO
YES
YES
UART_RX
configured as
GPIO input
Stop STM
Read elapsed time
Calculate baud rate
Baud rate
configuration
UART_RX == 1
Follow normal
UART boot protocol
Start STM
UART_RX pin is configured
to work with LINFlex module.
LINFlex module is configured in UART
mode with calculated baud rate.