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Flash program memory
ST7LITEUS2, ST7LITEUS5
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 or in-application programming.
The array matrix organization allows each sector to be erased and reprogrammed without
affecting other sectors.
4.2 Main
features
●
ICP (in-circuit programming)
●
IAP (in-application programming)
●
ICT (in-circuit testing) 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 and option byte row can be programmed or
erased.
●
In-circuit programming
In this mode, FLASH sectors 0 and 1 and option byte row can be programmed or
erased without removing the device from the application board.
●
In-application programming
In this mode, sector 1 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 I
2
C (in-circuit communication) which allows an ST7 plugged on a
printed circuit board (PCB) to communicate with an external programming device connected
via cable. ICP is performed in three steps:
●
Switch the ST7 to I
2
C mode. 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 I
2
C mode,
it fetches a specific RESET vector which points to the ST7 system memory containing
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