October 2011 Doc ID 022104 Rev 1 1/13
AN3965
Application note
STM32F40x/STM32F41x in-application programming
using the USART
1 Introduction
An important requirement for most Flash-memory-based systems is the ability to update
firmware when installed in the end product. This ability is referred to as in-application
programming (IAP). The purpose of this application note is to provide general guidelines for
creating an IAP application.
The STM32F4xx microcontroller can run user-specific firmware to perform IAP of the
microcontroller-embedded Flash memory. This feature allows the use of any type of
communication protocol for the reprogramming process. The USART is the example used in
this application note.
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Contents AN3965
2/13 Doc ID 022104 Rev 1
Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 IAP overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1 Principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2 IAP driver description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3 Running the IAP driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1 HyperTerminal configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.2 Executing the IAP driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4 IAP driver menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.1 Download image to the internal Flash memory . . . . . . . . . . . . . . . . . . . . . 7
4.2 Upload image from the internal Flash memory . . . . . . . . . . . . . . . . . . . . . 8
4.3 Execute the new program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.4 Disabling the write protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5 STM32F4xx IAP implementation summary . . . . . . . . . . . . . . . . . . . . . . 10
6 User program conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
7 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
