
Flash program memory
ST7L34, ST7L35, ST7L38, ST7L39
Doc ID 11928 Rev 7
4
Flash program memory
4.1
Introduction
The ST7 single voltage extended Flash (XFlash) is a non-volatile memory that can be
electrically erased and programmed either on a byte-by-byte basis or up to 32 bytes in
parallel.
The XFlash devices can be programmed off-board (plugged in a programming tool) or on-
board using in-circuit programming (ICP) or in-application programming (IAP).
The array matrix organization allows each sector to be erased and reprogrammed without
affecting other sectors.
4.2
Main features
●
In-circuit programming (ICP)
●
In-application programming (IAP)
●
In-circuit testing (ICT) for downloading and executing user application test patterns in
RAM
●
Sector 0 size configurable by option byte
●
Readout and write protection
4.3
Programming modes
The ST7 can be programmed in three different ways:
–
Insertion in a programming tool. In this mode, Flash sectors 0 and 1, option byte
row and data EEPROM (if present) can be programmed or erased.
–
In-circuit programming. In this mode, Flash sectors 0 and 1, option byte row and
data EEPROM (if present) can be programmed or erased without removing the
device from the application board.
–
In-application programming. In this mode, sector 1 and data EEPROM (if present)
can be programmed or erased without removing the device from the application
board and while the application is running.
4.3.1
In-circuit programming (ICP)
ICP uses a protocol called ICC (in-circuit communication) which allows an ST7 plugged on a
printed circuit board (PCB) to communicate with an external programming device connected
via a cable. ICP is performed in three steps:
–
Switch the ST7 to ICC mode (in-circuit communications). This is done by driving a
specific signal sequence on the ICCCLK/DATA pins while the RESET pin is pulled
low. When the ST7 enters ICC mode, it fetches a specific reset vector which points
to the ST7 system memory containing the ICC protocol routine. This routine
enables the ST7 to receive bytes from the ICC interface.
–
Download ICP driver code in RAM from the ICCDATA pin
–
Execute ICP driver code in RAM to program the Flash memory