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ON-BOARD PROGRAMMING METHODS FOR XFLASH AND HDFLASH ST7 MCUs

tion is the hardware watchdog that remains active: It must therefore be refreshed before per-

forming any Program/Erase operations on the FLASH.

2.2 IAP PRACTICAL IMPLEMENTATION

2.2.1 General architecture

As already stated, a firmware must already have been loaded into Sector 0. This firmware has

three purposes:

– Performing the Erase/Write operations on Sector 1 or 2 of program memory.

– Receiving the new data to be programmed.

– Managing the whole process protocol (Commands and status).

Therefore the firmware contained in the Sector 0 is generally based on three modules: Pro-

tocol layer, Data Transfer Layer and IAP Driver (Figure 2)

Figure 2. IAP Architecture

This chart only gives the generic scheme of an IAP application, however the various types of

New Data sources, Data Transfer physical supports, and the Protocol Layer interfaces can

lead to a wide range of practical implementations.

Software architecture

Protocol Layer

Data Transfer Layer

IAP Driver

MCU RAM

MCU FLASH

New Data

Data Flow

Commands

Status