
DocID13284 Rev 2
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UM0404
The bootstrap loader
from location 00’0000
H
of the internal Flash (User Flash) or the external memory, as
programmed via pin EA.
Note:
If a bidirectional Software Reset is executed, and external memory boot is selected
(EA
=
0), a degeneration of the Software Reset event into a Hardware Reset can occur
(Refer to section for details). This would imply that P0L.4 becomes transparent, so to exit
from Bootstrap mode it would be necessary to release pin P0L.4 (it is no longer ignored).
15.2.8 Hardware
requirements
Although the new bootstrap loader has been designed to be compatible with the old
bootstrap loader, there are few hardware requirements related with the new bootstrap
loader:
•
External Bus configuration: need to have four segment address lines or less (keep
CAN I/Os available);
•
Usage of CAN pins (P4.5 and P4.6): even in bootstrap via UART, P4.5 (CAN1_RxD)
cannot be used as Port output but only as input. The pin P4.6 (CAN1_TxD) can be
used as input or output.
•
Level on UART RxD and CAN1_RxD during the bootstrap phase (see
Step 2): must be 1 (external pull-up’s recommended).
15.3
Standard bootstrap with UART (RS232 or K-Line)
15.3.1 Features
ST10F276 bootstrap via UART has the same overall behavior as the old ST10 bootstrap via
UART:
•
Same bootstrapping steps;
•
Same bootstrap method: analyze the timing of a predefined byte, send back an
acknowledge byte, load a fixed number of bytes and run then;
•
Same functionalities: boot with different crystals and PLL ratios.