FDCAN internal peripheral

Article purpose

The purpose of this article is to:

• briefly introduce the FDCAN peripheral and its main features
• indicate the level of security supported by this hardware block
• explain how each instance can be allocated to the two runtime contexts and linked to the corresponding software components
• explain, when necessary, how to configure the FDCAN peripheral.

Peripheral overview

FDCAN peripheral handles data communication in a Controller Area Network (CAN) bus system using message-based protocol originally designed for in-vehicle communication. The CAN subsystem consists of two CAN modules (FDCAN1 and FDCAN2), a shared message RAM and an optional clock calibration unit.

Features

Both FDCAN instances are compliant with classic CAN protocol and CAN FD (CAN with Flexible Data-Rate) protocol. In addition, FDCAN1 supports time triggered CAN (TTCAN).

FDCAN1 and FDCAN2 share a dedicated 10 Kbyte CAN SRAM for message transfers.

Refer to STM32MP15 reference manuals for the complete list of features, and to the software components, introduced below, to see which features are implemented.

Security support

FDCAN is a non secure peripheral.

Peripheral usage and associated software

Boot time

The FDCAN is not used at boot time.

Runtime

Overview

FDCAN instances can be allocated to:

• the Arm^® Cortex^®-A7 non-secure core to be controlled in Linux^® by the NetDev framework (See CAN overview)

or

• the Arm^® Cortex^®-M4 to be controlled in STM32Cube MPU Package by STM32Cube FDCAN driver

Software frameworks

Domain	Peripheral	Software frameworks			Comment
		Cortex-A7 secure (OP-TEE)	Cortex-A7 non-secure (Linux)	Cortex-M4 (STM32Cube)
Networking	FDCAN		Linux net/can framework	STM32Cube FDCAN driver

Peripheral configuration

The configuration is applied by the firmware running in the context to which the peripheral is assigned. The configuration can be done alone via the STM32CubeMX tool for all internal peripherals, and then manually completed (particularly for external peripherals) according to the information given in the corresponding software framework article. When the FDCAN peripheral is assigned to the Linux^® OS, it is configured through the device tree according to the information given in the FDCAN device tree configuration article.

Peripheral assignment

Internal peripherals assignment table template

| rowspan="2" | Networking
| rowspan="2" | FDCAN
| FDCAN1
| 
| ☐
| ☐
| Assignment (single choice)
|-
| FDCAN2
| 
| ☐
| ☐
| Assignment (single choice)
|-

|}

How to go further

Use this paragraph to add more information and introduce other documentation such as Application Notes (AN)

References