ST10F269Z2QX View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'ST10F269Z2QX' PDF : 161 Pages View PDF
ST10F269Z2Qx
Figure 7 : Memory Configuration after Reset
16M Bytes
Segment
Access to:
255
16M Bytes
Segment
Access to:
255
16M Bytes
Segment
Access:
255
external
bus
2
disabled
2
external
bus
enabled
2
depends on
reset config
EA, Port0
1
IRAM
1
IRAM
1
IRAM
0
Test
Flash
User internal
Flash
Flash enabled
0
Test
Flash
User internal
Flash
Flash enabled
0 User
Flash
depends on
reset config
EA, Port0
BSL mode active
EA pin
Code fetch from internal
Flash area
Data fetch from internal
Flash area
Yes (P0L.4=’0’)
High
Test-Flash access
User Flash access
5.6.3 - Loading the Startup Code
After sending the identification Byte the BSL
enters a loop to receive 32 Bytes via ASC0. These
Byte are stored sequentially into locations
00’FA40h through 00’FA5Fh of the internal RAM.
So up to 16 instructions may be placed into the
RAM area. To execute the loaded code the BSL
then jumps to location 00’FA40h, which is the first
loaded instruction.
The bootstrap loading sequence is now
terminated, the ST10F269Z2Qx remains in BSL
mode, however. Most probably the initially loaded
routine will load additional code or data, as an
average application is likely to require
substantially more than 16 instructions. This
second receive loop may directly use the
pre-initialized interface ASC0 to receive data and
store it to arbitrary user-defined locations.
This 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. It may also contain a
code sequence to change the system
configuration and enable the bus interface to store
the received data into external memory.
Yes (P0L.4=’0’)
Low
Test-Flash access
User Flash access
No (P0L.4=’1’)
Access to application
User Flash access
User Flash access
This process may go through several iterations or
may directly execute the final application. In all
cases the ST10F269Z2Qx will still run in BSL
mode, that means with the watchdog timer
disabled and limited access to the internal Flash
area.
All code fetches from the internal Flash area
(00’0000h...00’7FFFh or 01’0000h...01’7FFFh, if
mapped to segment 1) are redirected to the
special Boot-ROM. Data fetches access will
access the internal Boot-ROM of the
ST10F269Z2Qx, if any is available, but will return
undefined data on ROMless devices.
5.6.4 - Exiting Bootstrap Loader Mode
In order to execute a program in normal mode, the
BSL mode must be terminated first. The
ST10F269Z2Qx exits BSL mode upon a software
reset (ignores the level on P0L.4) or a hardware
reset (P0L.4 must be high). After a reset the
ST10F269Z2Qx will start executing from location
00’0000h of the internal Flash or the external
memory, as programmed via pin EA.
32/161
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