ST AN1474 APPLICATION NOTE
AN1474
APPLICATION NOTE
ST92F150 A ND ST92F120 PROBLEM RESOLUTION
GUIDELINES
by Microcontroller Division Applications
INTRODUCTION
The ST92F12 0 and ST 92F15 0 are par t of the sa me fa mily of pow erful m icrocon trollers fr om
STMicroelectronics, featuring single voltage flash memory and an innovative E3prom concept.
This document gives guidelines on resolving several common application problems that have
been reported by ST Application Engineers.
Testflash features
The testflash features are described in the ST92F120 and ST92F150 datasheets.
Located in a reserved flash area, the TestFlash contains the bootcode which performs the
E3prom initialization, provides the possibility to program the flash by In System Programming
(refer to the application note
then jumps to the start address application code via the reset vector.
AN1450 ST9 Flash Programming
for a detailed description) and
AN1474/1001 1/10
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ST92F150 AND ST92F120 PROBLEM RESOLUTION GUIDELINES
1 EXTERNAL WATCHDOG ROUTINE
During the bootcode execution (from 12.5 ms up to 75ms if an aborted E3prom write operation
is detected), a code routine provided by the user may be executed to refresh an external
watchdog.
The routine address offset is located at addresses 0x000006h and 0x000007h while the segment where the routine is located has to be written in 0x000009h.
You must fill the word at the address 0x000006h with 0xffffh if your application does not use an
external watchdog.
Startup file example (usually called crtbegin.spp) :
.org 0x06
.word 0xffff
Refer to the application examples provided with the ST9+ User Guide.
1.1 PROBLEM DESCRIPTION
The application is not executed at all and it is not possible to communicate by ISP with the programming board.
1.2 ANALYSIS
When the chip is read directly with the programming board, the contents of addresses
0x000006h and 0x000007h is not equal to 0xFFh.
These addresses in the application code are not equal to 0xFF whereas an external watchdog
routine is not provided.
1.3 RESOLUTION
Modify the application code as mentioned at the beginning of this section and erase and reprogram the device.
There is no way to modify this chip by ISP, it has to be unsoldered.
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ST92F150 AND ST92F120 PROBLEM RESO LUTION GUIDELINES
2 ST92F120 RESET VECTOR
One of the powerful features provided by the ST9 Flash device family is the possibility to upgrade the application code by downloading and programming through an I/O interface on the
MCU (refer to the application note
AN1275 In Application Programming for the ST 92F120
a detailled description).
In case of a parasitic reset during the flash upgrade operation, the application must be able to
recover safely by executing the bootloader code.
To perform this, the bootloader is present in the flash sector where the application starts, the
one pointed to by the reset vector. This sector must never be erased.
This is why the reset vector is always located in the smallest sector.
ST92F120 60Kbyte Flash device map
Sector Size
F0 4 Kbyte
F1 48 Kbyte
F2 8 Kbyte
for
ST92F120 128Kbyte Flash device map
Sector Size
F0 64 Kbyte
F1 48 Kbyte
F2 8 Kbyte
F3 8 Kbyte
ST92F150 60 Kbyte Flash device map
Sector Size
F0 8 Kbyte
F1 8 Kbyte
F2 32 Kbyte
F3 12 Kbyte
ST92F150 128Kbyte Flash device map
Sector Size
F0 8 Kbyte
F1 8 Kbyte
F2 48 Kbyte
F3 64 Kbyte
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