ST AN3078 Application note

July 2010 Doc ID 16393 Rev 1 1/10

AN3078

Application note

STM32™ in-application programming

over the I²C bus

Introduction

A key requirement for most Flash-memory-based systems is the ability to update firmware

once the system is installed in the end product. This is referred to as in-application

programming (IAP). The purpose of this application note is to provide general guidelines for

creating an IAP application.

STM32F10x microcontrollers can run user-specific firmware to perform the IAP of their

embedded Flash memory. This feature allows the use of any type of communication protocol

for the reprogramming process (such as CAN, USART, USB, SPI, I2C, etc.).

This application note describes how to perform in-application programming using the

STM32F10x’s I2C peripheral. As a first step, the Aardvark tool is used as the host sending

the IAP commands to the STM32F10x. As a second step, the host is another STM32F10x

microcontroller that behaves as a bridge between the PC and the target (USB/I2C bridge).

The STM32F10x behaves as an I2C memory that can be programmed, erased and read via

the I2C/ interface.

For further information on the STM32F10x family features, pinout, electrical characteristics,

mechanical data and ordering information, please refer to the STM32F10x datasheets

available from the STMicroelectronics website: www.st.com.

The STM32 firmware libraries are available from www.st.com.

The versions of the Aardvark host adapter used during the development are listed below:

● Firmware: Aardvark I2C/SPI Control Center v3.52 -2009.0130

● Hardware: Aardvark I2C/SPI v3.0

For further information on the Aardvark host adapter and its software, please refer to its

documentation on www.st.com.

www.st.com

Contents AN3078

2/21 Doc ID 16393 Rev 1

Contents

1 IAP overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1.1 Principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1.2 User program conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1.3 Global flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1.4 IAP commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1.4.1 Read command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1.4.2 Write command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

1.4.3 Erase page command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1.4.4 Erase User Space memory command . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1.4.5 Go To User Code command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2 STM32 IAP over the I

2

C peripheral . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.1 Hardware description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.2 Software description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.2.1 I

2

C packet description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.2.2 IAP I

2

C Read command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.2.3 IAP I

2

C Write command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

2.2.4 IAP I

2

C Erase Page command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

2.2.5 IAP I

2

C Erase User Space Memory command . . . . . . . . . . . . . . . . . . . 12

2.2.6 IAP I

2

C Go To User Code command . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

2.2.7 IAP I

2

C flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3 Sending IAP commands to a target . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

3.1 Sending IAP I

2

C commands using the Aardvark I

2

C host

adapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

3.1.1 Aardvark I

2

C interface mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

3.1.2 Aardvark I

2

C batch mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.2 Sending IAP commands using another STM32 device as a

bridge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

3.2.1 Principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

3.2.2 Hardware description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

3.2.3 Firmware description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

4 IAP timings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

AN3078 Contents

Doc ID 16393 Rev 1 3/21

5 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

List of tables AN3078

4/21 Doc ID 16393 Rev 1

List of tables

Table 1. IAP timings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Table 2. Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

AN3078 List of figures

Doc ID 16393 Rev 1 5/21

List of figures

Figure 1. Flash memory usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Figure 2. Global flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Figure 3. Read command flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Figure 4. Write command flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Figure 5. Erase Page command flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Figure 6. User Space Memory Erase command flowchart. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Figure 7. Go To User Code command flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Figure 8. Hardware connection between the host master and the STM32 I

2

C target . . . . . . . . . . . . 11

Figure 9. Read packet sequence using the I

2

C protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Figure 10. Write packet sequence using the I

2

C protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Figure 11. Erase Page packet sequence using the I

2

C protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Figure 12. Erase User Space Memory packet sequence using the I

2

C protocol . . . . . . . . . . . . . . . . . 12

Figure 13. Go To User Code sequence using the I

2

C protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Figure 14. IAP I

2

C flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Figure 15. Configuration of Aardvark I

2

C host adapter in interface modet . . . . . . . . . . . . . . . . . . . . . 14

Figure 16. Read command using the Aardvark I

2

C interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Figure 17. Read command I

2

C transaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Figure 18. Write command using the Aardvark I

2

C interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Figure 19. Write command I

2

C transaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Figure 20. Aardvark I

2

C configuration using the Batch mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Figure 21. IAP I

2

C Read command in batch script . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Figure 22. IAP I

2

C Write command in batch script . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Figure 23. Hardware connection between the PC, the STM32 bridge and the I

2

C

target. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Figure 24. Modified DFU firmware architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

IAP overview AN3078

6/10 Doc ID 16393 Rev 1

1 IAP overview

1.1 Principle

The IAP driver must be programmed from the Flash memory base address via the JTAG or

SWD interface using a development toolchain. This driver uses the I2C to load a file from

the host to the STM32F10x’s internal Flash memory, and then executes it.

1.2 User program conditions

The IAP application is loaded from the Flash memory base address (0x0800 0000) to the

0x0800 0FFF address. The user application therefore has to be loaded from the

0x0800 1000 address to the top Flash memory address.

Figure 1. Flash memory usage

Flash memory

0x0800 0FFF

0x0800 1000

IAP code

Vector table

User code

Vector table

0x0800 0000

To p F l ash memory

address

User space

memory

IAP space

memory

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AN3078 IAP overview

Doc ID 16393 Rev 1 7/10

1.3 Global flowchart

Figure 2. Global flowchart

A pin connected to a push-button is used to select between jumping to the user application

and executing IAP for reprogramming purposes:

● at reset, when the push-button is pressed IAP is executed

● otherwise, a jump to the user program is performed

1.4 IAP commands

1.4.1 Read command

The read command is used to read data from the STM32’s Flash memory, starting from any

Flash address in the user space memory.

Start

User button

pressed

Switch to IAP

IAP program

Yes

No

Reset

pressed

Yes

No

Switch to User program

User program

Reset

pressed

Yes

No

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