ST72260Gx, ST72262Gx, ST72264Gx
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 organisation allows each sector to be erased and reprogrammed without affecting other sectors.
4.2 Main Features
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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
Read-out and write protection against piracy
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 ICC (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 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
Depending on the ICP Driver code downloaded in
RAM, FLASH memory programming can be fully customized (number of bytes to program, program locations, or selection of the serial communication interface for downloading).
4.3.2 In Application Programming (IAP)
This mode uses an IAP Driver program previously programmed in Sector 0 by the user (in ICP mode).
This mode is fully controlled by user software. This allows it to be adapted to the user application, (user-defined strategy for entering programming mode, choice of communications protocol used to fetch the data to be stored etc.)
IAP mode can be used to program any memory areas except Sector 0, which is write/erase protected to allow recovery in case errors occur during the programming operation.
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