ST10F269Z2QX View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'ST10F269Z2QX' PDF : 161 Pages View PDF
ST10F269Z2Qx
When the ST10F269Z2Qx has entered BSL mode, the following configuration is automatically set (values
that deviate from the normal reset values, are marked):
Watchdog Timer:
Context Pointer CP:
Stack Pointer SP:
Register S0CON:
Register S0BG:
Disabled
FA00h
FA40h
8011h
Acc. to ‘00’ Byte
Register SYSCON:
Register STKUN:
Register STKOV:
Register BUSCON0:
P3.10 / TXD0:
DP3.10:
0E00h
FA40h
FA0Ch 0<->C
acc. to startup configuration
‘1’
‘1’
In this case, the watchdog timer is disabled, so the
bootstrap loading sequence is not time limited.
Pin TXD0 is configured as output, so the
ST10F269Z2Qx can return the identification Byte.
Even if the internal Flash is enabled, no code can
be executed out of it.
The hardware that activates the BSL during reset
may be a simple pull-down resistor on P0L.4 for
systems that use this feature upon every
hardware reset.
A switchable solution (via jumper or an external
signal) can be used for systems that
only temporarily use the bootstrap loader (see
Figure 6).
After sending the identification Byte the
ASC0 receiver is enabled and is ready to
receive the initial 32 Bytes from the host. A half
duplex connection is therefore sufficient to feed
the BSL.
5.6.2 - Memory Configuration After Reset
The configuration (and the accessibility) of the
ST10F269Z2Qx’s memory areas after reset in
Bootstrap-Loader mode differs from the standard
case. Pin EA is not evaluated when BSL mode is
selected, and accesses to the internal Flash area
are partly redirected, while the ST10F269Z2Qx is
in BSL mode (see Figure 7). All code fetches are
made from the special Boot-ROM, while data
accesses read from the internal user Flash. Data
accesses will return undefined values on
ROMless devices.
The code in the Boot-ROM is not an invariant
feature of the ST10F269Z2Qx. User software
should not try to execute code from the internal
Flash area while the BSL mode is still active, as
these fetches will be redirected to the Boot-ROM.
The Boot-ROM will also “move” to segment 1,
when the internal Flash area is mapped to
segment 1 (see Figure 7).
Figure 6 : Hardware Provisions to Activate the BSL
External
Signal
POL.4
RPOL.4
8kΩ
Circuit 1
POL.4
Normal Boot
BSL
RPOL.4
8kΩ
Circuit 2
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