ST AN3078 Application note

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.

July 2010 Doc ID 16393 Rev 1 1/10

www.st.com

Contents AN3078

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 I2C peripheral . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

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

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

2.2.1 I2C packet description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.2.2 IAP I

2.2.3 IAP I

2.2.4 IAP I

2.2.5 IAP I

2.2.6 IAP I

2.2.7 IAP I

2

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

2

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

2

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

2

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

2

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

2

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

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

3.1 Sending IAP I2C commands using the Aardvark I2C host

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

3.1.1 Aardvark I2C interface mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

3.1.2 Aardvark I

3.2 Sending IAP commands using another STM32 device as a

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

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

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

2

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

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

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

2/21 Doc ID 16393 Rev 1

AN3078 Contents

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

Doc ID 16393 Rev 1 3/21

List of tables AN3078

List of tables

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

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

4/21 Doc ID 16393 Rev 1

AN3078 List of figures

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
Figure 9. Read packet sequence using the I
Figure 10. Write packet sequence using the I
Figure 11. Erase Page packet sequence using the I
Figure 12. Erase User Space Memory packet sequence using the I
Figure 13. Go To User Code sequence using the I
Figure 14. IAP I
Figure 15. Configuration of Aardvark I
Figure 16. Read command using the Aardvark I
Figure 17. Read command I
Figure 18. Write command using the Aardvark I
Figure 19. Write command I
Figure 20. Aardvark I
Figure 21. IAP I
Figure 22. IAP I

2

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

2

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

2

2

2

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

2

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

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

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

2

2

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

2

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

2

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

2

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

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

2

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

2

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

2

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

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

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

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

2

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

2

C

Doc ID 16393 Rev 1 5/21

IAP overview AN3078

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

ai17364

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

6/10 Doc ID 16393 Rev 1

AN3078 IAP overview

1.3 Global flowchart

Figure 2. Global flowchart

Start

Switch to IAP

IAP program

No

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.

Reset

pressed

Yes

Yes

User button

pressed

No

Switch to User program

User program

No

Reset

pressed

Yes

ai17365

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