ST10F272M datasheet(43/175 Pages) STMICROELECTRONICS

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ST10F272M

Bootstrap loader

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Bootstrap loader

The ST10F272M implements Boot capabilities in order to:

●

Support bootstrap via UART or bootstrap via CAN for the standard bootstrap

●

Support a Selective Bootstrap Loader, to manage the bootstrap sequence in a different

way

6.1

Selection among user-code, standard or selective bootstrap

The boot modes are triggered with a special combination set on Port0L[5...4]. Those

signals, as other configuration signals, are latched on the rising edge of RSTIN pin.

●

Decoding of reset configuration (P0L.5 = 1, P0L.4 = 1) selects the normal mode (also

called User mode) and selects the user Flash to be mapped from address 00’0000h.

●

Decoding of reset configuration (P0L.5 = 1, P0L.4 = 0) selects ST10 standard bootstrap

mode (Test-Flash is active and overlaps user Flash for code fetches from address

00'0000h; user Flash is active and available for read accesses).

●

Decoding of reset configuration (P0L.5 = 0, P0L.4 = 1) activates new verifications to

select which bootstrap software to execute:

–

if the User mode signature in the User Flash is programmed correctly, then a

software reset sequence is selected and the User code is executed;

–

if the User mode signature is not programmed correctly in the user Flash, then the

User key location is read again. Its value determines which communication

channel will be enabled for bootstrapping.

6.2

Standard bootstrap loader

After entering the standard BSL mode and the respective initialization, the ST10F272M

scans the RxD0 line and the CAN1_RxD line to receive either a valid dominant bit from the

CAN interface or a start condition from the UART line.

Start condition on UART RxD: ST10F272M starts standard bootstrap loader. This

bootstrap loader is identical to that of other ST10 devices (example: ST10F269, ST10F168).

Valid dominant bit on CAN1 RxD: ST10F272M start bootstrapping via CAN1.

Caution:

As both UART_RxD and CAN1_RxD lines are polled to detect a start of communication,

ensure a stable level on the unused channel by adding a pull-up resistor.

Table 26.

ST10F272M boot mode selection

P0.5

P0.4

ST10 decoding

User mode: User Flash mapped at 00’0000h

Standard Bootstrap Loader: User Flash mapped from 00’0000h, code fetches

redirected to Test-Flash at 00’0000h

Selective Boot mode: User Flash mapped from 00’0000h, code fetches

redirected to Test-Flash at 00’0000h (different sequence execution compared to

Standard Bootstrap Loader)

Reserved

ST10F272M Datasheet(PDF) 43 Page - STMicroelectronics

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