ST10F296E datasheet(81/346 Pages) STMICROELECTRONICS

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ST10F296E

The bootstrap loader

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6.4.4

Loading the startup code via CAN

After sending the acknowledge byte the BSL enters a loop to receive 128 bytes via CAN1.

Note:

The number of bytes loaded when booting via the CAN interface has been extended to 128

bytes to allow re-configuration of the CAN bit timing register with the best timings

(synchronization window, ...). This can be achieved by the following sequence of

instructions:

ReconfigureBaudRate:

MOV R1,#041h

MOV DPP3:0EF00h,R1 ; Put CAN in Init, enable Configuration Change

MOV R1,#01600h

MOV DPP3:0EF06h,R1 ; 1MBaud at Fcpu = 20 MHz

These 128 bytes are stored sequentially into locations 00’FA40H to 00’FABFH of the IRAM.

So, up to 64 instructions may be placed into the RAM area. To execute the loaded code the

BSL jumps to location 00’FA40H, the first loaded instruction. The bootstrap loading

sequence is now terminated, however, the ST10F296E remains in BSL mode. It is likely that

the initially loaded routine loads additional code or data (because an average application is

likely to require substantially more than 64 instructions). This second receive loop may

directly use the pre-initialized CAN interface to receive data and store it to arbitrary user-

defined locations.

The second level of loaded code may be the final application code. It may also be another,

more sophisticated, loader routine that adds a transmission protocol to enhance the integrity

of the loaded code or data. In addition, it may contain a code sequence to change the

system configuration and enable the bus interface to store the received data into the

external memory.

This process may go through several iterations or may directly execute the final application.

In all cases the ST10F296E runs in BSL mode, with the watchdog timer disabled and limited

access to the internal Flash area. All code fetches from the internal Flash area (01’0000H

...08’FFFFH) are redirected to the special Test-Flash. Data read operations access the

internal Flash of the ST10F296E, if any is available, but return undefined data on ROM-less

devices.

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ST10F296E Datasheet(PDF) 81 Page - STMicroelectronics

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