Introduction
This application note describes the FDCAN protocol used in the STM32 microcontroller bootloader, providing details on each
supported command.
This document applies to STM32 products embedding any bootloader version, as specified in application note STM32 system
memory boot mode (AN2606), available from www.st.com. These products are listed in Table 1.
For more information about the FDCAN hardware resources and requirements for their device bootloader, users are advised to
refer to application note AN2606.
Table 1. Applicable products
Type Product series
Microcontrollers
STM32G0 Series
STM32G4 Series
STM32H7 Series
STM32L5 Series
FDCAN protocol used in the STM32 bootloader
AN5405
Application note
AN5405 - Rev 2 - June 2021
For further information contact your local STMicroelectronics sales office.
www.st.com
1Bootloader code sequence
The 32-bit microcontrollers in the STM32G0 Series, STM32G4 Series, STM32H7 Series, and STM32L5 Series
are based on the Arm® Cortex® processor. They are referred to as STM32 in this document.
Figure 1 presents the global sequence for the STM32 bootloader with FDCAN.
Figure 1. Bootloader for STM32 with FDCAN
Frame detected
on FDCAN Rx
pin
Wait for a
command
Get
cmd routine
Read Memory
cmd routine
(Optional)
Routines for
loading into
RAM
Go
cmd routine
Jump to Address
Once the system memory boot mode is entered and the STM32 device is configured, (refer to application note
AN2606 for additional details), the bootloader code waits for a frame on the FDCANx_Rx pin.
Note: Arm is a registered trademark of Arm Limited (or its subsidiaries) in the US and/or elsewhere.
AN5405
Bootloader code sequence
AN5405 - Rev 2 page 2/37
