ST10F276 datasheet(52/229 Pages) STMICROELECTRONICS

52 / 229 page

Bootstrap loader

ST10F276

52/229

Note:

As long as ST10F276 is in BSL, the user’s software should not try to execute code from the

internal IFlash, as the fetches are redirected to the Test-Flash.

5.2.6

Loading the start-up code

After the serial link initialization sequence (see following chapters), the BSL enters a loop to

receive 32 bytes (boot via UART) or 128 bytes (boot via CAN).

These bytes are stored sequentially into ST10F276 Dual-Port RAM from location 00’FA40h.

To execute the loaded code, the BSL then jumps to location 00’FA40h. The bootstrap

sequence running from the Test-Flash is now terminated; however, the microcontroller

remains in BSL mode.

Most probably, the initially loaded routine, being the first level user code, will load additional

code and data. This first level user code may use the pre-initialized interface (UART or CAN)

to receive data and a second level of code, and store it in arbitrary user-defined locations.

This second level of code may be

●

the final application code

●

another, more sophisticated, loader routine that adds a transmission protocol to

enhance the integrity of the loaded code or data

●

a code sequence to change the system configuration and enable the bus interface to

store the received data into external memory

In all cases, the ST10F276 still runs in BSL mode, that is, with the watchdog timer disabled

and limited access to the internal IFLASH area.

Figure 8.

Memory configuration after reset

16 Mbytes

BSL mode active

Yes (P0L.4 = ‘0’)

No (P0L.4 = ‘1’)

EA pin

High

Low

According to application

Code fetch from

internal FLASH area

Test-FLASH access

User IFLASH access

Data fetch from

internal FLASH area

User IFLASH access

int. FLASH

enabled

access to

external

bus

disabled

access to

int.

RAM

int. FLASH

enabled

access to

external

bus

enabled

access to

int.

RAM

Depends on

reset config.

int.

RAM

Depends on

reset config.

(EA, P0)

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