Boot Assist Module (BAM)
MPC5606S Microcontroller Reference Manual, Rev. 7
Freescale Semiconductor 173
6.5.4.4 Download and execute the new code
From a high-level perspective, the download protocol follows steps:
0. (optional step) Send message and receive acknowledge message for autobaud or autobit rate
selection.
1. Send 64-bit password.
2. Send start address, size of downloaded code in bytes, and VLE bit
1
.
3. Download data.
4. Execute code from start address.
Each step must be completed before the next step starts.
The communication is done in half-duplex manner. Any transmission from host is followed by the MCU
transmission:
1. Host sends data to MCU and starts waiting.
2. MCU echoes to host the data received.
3. MCU verifies if echo is correct.
— If data is correct, the host can continue to send data.
— If data is not correct, the host stops transmitting and the MCU needs to be reset.
All multi-byte data structures are sent with MSB first.
A more detailed description of these steps follows.
6.5.4.5 Download 64-bit password and password check
The first 64 bits received represent the password. This password is sent to the Password Check procedure,
which verifies if it is correct.
Password check data flow is shown in Figure 6-5 where:
• SSCM_STATUS.SEC = 1 means flash secured
• SSCM_STATUS.PUB = 1 means flash with public access
In case of flash memory with public access, the received password is compared with the public password
0xFEED_FACE_CAFE_BEEF.
16 19200 400K
20 24000 500K
40 48000 1M
1. Since this device supports only VLE code and it does not support Book E code, this flag is used only for backward compatibility.
Table 6-6. Serial Boot mode without autobaud—baud rates (continued)
Crystal frequency
(MHz)
LINFlex baud rate
(baud)
CAN bit rate
(bit/s)
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