Guide to USB development resources on STM32

[Gyessine]

Introduction

This article gives you the key information you need to dive into USB development on STM32. It mentions various resources, including training (MOOCs), articles, and application notes, that can help understand USB theory and hardware implementation.

1. USB theory

1.1 Starting with the fundamentals

 If you’re new to the world of USB on STM32 products, we really recommend watching our USB MOOC and consult the course materials. This will help you dive deep into USB theory and understand the fundamentals like:

• USB protocol basic: STM32 USB training introduction
• Endpoints and data packets structure: Watch the STM32 USB transfers training and read the "How to select suitable endpoints for your STM32 USB application" article.

• USB descriptors: We recommend watching the STM32 USB descriptors training.
• USB STM32 standard class overview: To identify which class you need, watch the STM32 USB standard class training.
• USB states: Watch the STM32 USB training introduction.

You can also read the ST Wiki: USB protocol basics from section 1.0 to 1.15.

For more technical information related to USB, see the USB specification and USB class specifications that can be downloaded from https://www.usb.org/developers

1.2 USB hardware implementation on an STM32

USB hardware implementation is and will always be one of the most delicate and always asked about topics. The AN4879 covers most of what you need to know in an advanced way like: 

• Internal and external clocks 

Check the relevant datasheet for your product. For more information, check section 2.4 "Clock" in AN4879.

• Internal and external PHYs required for HS and internal PHYs

For this point, you can check this article about ULPI compatibility or from section 3.3 to section 3.5 of AN4879.

• ESDs and concept of VBUS sensing

Check this article for more specific overview or check section 2.6 “VBUS sensing detection point” and section 2.3 "Protection against ESD and EMI" in AN4879.

• Hardware architecture for DEVICE and HOST mode

To see STM32 products USB specifications, you can refer to the section 2, “USB on STM32 products” in AN4879.

You can also refer to specific application notes and datasheets for detailed hardware implementation guidance like the application notes for H5, F7, H7R/S, and H72x/H73x.

These application notes are titled under the name: “Getting started with STM32Xx MCU hardware development”.

You can also always refer to each product’s datasheets, reference manual, application note, and schematics to see some ST hardware implementation (noted as MBxxxx example: MB997 for F407G-Disco, MB1364 for STM32H757-EVAL.)

1.3 Middlewares

ST uses majorly 2 middlewares through their range of product, which is ST USB middleware and Azure USBX middleware.

1.3.1 ST USB middleware

ST USB middleware provides libraries and tools to facilitate USB device and host functionality on STM32 microcontrollers. It’s composed mainly of the device library and host library.

1.3.1.1 Device mode

For a general understanding of device mode, watch the STM32 USB device library training, read the fifth section in the wiki, and view the STM32 USB device library PDF.

For more in-depth review, check UM1734, sixth point USB device library of UM1021 or UM0424 for USB-FS demos.

If you’re still searching for helpful resources on the subject, here are some extra links that might help:

• DFU class: AN3156 for DFU basic commands explanation
• Audio class: UM2195 

1.3.1.2 Host mode

You can watch the STM32 USB host library training, read the “USB host library overview” in the ST wiki, and explore the STM32 USB host library PDF.

For a deep explanation, check the section 7. "USB host library" in UM1021.

1.3.2 Azure USBX middleware

As a general start you can check our USBX overview MOOC

1.3.2.1 Device mode:

You can review the second section of this WIKI and check the "USBX device stack user guide” and “USBX device stack supplemental” of USBX GitHub documentation 

1.3.2.2 Host mode

You can review this Link and check the “USBX host stack user guide” and “USBX host stack supplemental” sections of USBX GitHub documentation 

2. USB Projects and applications

ST provides some USB applications examples in almost every product in their range
You can refer to them buy following your product firmware buy this path

C:\Users\xxxxxx\STM32Cube\Repository\STM32Cube_FW_xx_Vx.xx.x\Projects\xxxxxxxxx\Applications\

This is the default path, but it may change if you chose another location for installing the firmware.

Or in our GitHub: STMicroelectronics/STM32CubeXX
For example: STM32CubeH7/Projects at master · STMicroelectronics/STM32CubeH7
or visit stm32-usbx-examples.

2.1 ST USB middleware

Here are some USB application examples for some of our products (be aware that you can find the same application in other products just check our GitHub or your products firmware as we explained

Class	Mode	Details
HID	Device	HID mouse application.
		CUSTOM HID standalone application or visit this project tutorial and check USB HID articles part 1 and part 2
		HID LPM application
	Host	HID mouse and keyboard application or visit this tutorial.
CDC	Device	CDC transmit application, or follow this tutorial
	Host	CDC Host application.
DFU	Device	DFU mode application or follow the device mode tutorial
		How to modify DFU firmware examples check this article
		How to jump to system bootloader check this article
		Open bootloaders check this article
		Dual bank demos check this GitHub example
	Host	Check STM32H743-EVAL firmware or follow the host mode tutorial
MSC	Device	Mass storage class application or follow the device mode tutorial
		Bootloader USB mass storages check this GitHub example
	Host	Check your firmware or follow the device mode tutorial
		mass storage class application
AUDIO	Device	STM32H747-EVAL firmware example
DUAL CORE	Device	CDC & HID class application
	Host	MSC & HID application
Dual Role	Device/Host	HID host & CDC device article
Composite	device	HID & MSC article
		DUAL CDC ACM article
		(HID + CDC) tutorial and project
		(DFU + HID) article

2.2 USBX

Here are some USB application examples for some of our products (be aware that you can find the same application in other products just check our GitHub or your products firmware as we explained

Class	Mode	Details
HID	Device	HID mouse
		HID mouse standalone application
	Host	HID mouse and keyboard
		HID mouse & keyboard standalone
CDC	Device	CDC ACM   How to implement the USB device CDC class using the Azure article
		CDC LAB tutorial
		Dual CDC project with USBX stack GitHub link
	Host	CDC host project or check this article
DFU	Device	Enable DFU mode project
MSC	Device	Mass storage application
		How to implement USB mass storage device standalone
	Host	Mass storage class host project
AUDIO	Device	Device_Audio_2.0 application
		Device_Audio_2.0_Standalone application
	HOST	Host_Audio_2.0 application
Video	Device	STM32N6 firmware example
CCID	Device	Ux_Device_CCID
PIMA	Device	Ux_Device_PIMA_MTP
Printer	Device	Ux_Device_Printer
RNDIS	Device	Ux_Device_RNDIS
	Host	Host_VIDEO application
Dual Class	Host	USB Host Human Interface "HID" and Mass Storage “MSC"
Composite	DEVICE	MOOC - Azure RTOS workshop - USBX lab - composite device
		How to implement the USB device composite class using the Azure article and associated project
	HOST	Host_HID_CDC_ACM application
Standalone	HID	How to implement USBX in standalone mode article How to add USBX to an STM32 FreeRTOS™ project

Be also aware that some of our products are native STM32 classic middleware but also can use the USBX Azure package like H7, H7RS, L5, WB, G4, G0, F7, F4, WL, and L4 like we did in this article

And some of them are USBX stack natively but can also use the classic middleware accordingly. With them like STM32WBA, STM32U3, STM32U0, STM32N6, STM32C0, STM32U5, STM32H5.

However, you can implement STMicroelectronics classic USB device middleware with these families. Like we did in this article.

2.2 Other USB features

How to configure USB FIFO over USB OTG controller over STM32

How to configure the packet memory area in STM32 USB controller

Practical use cases on how to configure packet memory area

Practical use cases to manage FIFO in USB OTG controller

2.3 USB + Other peripherals

• How to run Bluetooth® Low Energy P2P server with USB CDC on STM32WB article part 1 and part 2.

3. FAQ and common errors

• USB device not recognized
• How to set USB CDC line coding
• FAQ: Configuring the VDD50USB and VDD33USB pins on STM32H7 when not using USB
• FAQ: Possible communication failure between STLINK and recent computers
• Section 5. “Frequently asked questions” regarding USB hardware in AN4879
• Section 8. “Frequently asked questions” regarding USB OTG in UM1021
• Section 7. "Frequently asked questions" regarding device library in UM1734
• How to correctly setup your application to use USB... - STMicroelectronics Community

Conclusion

Overall, the article provides a thorough guide for USB development on STM32. It includes various resources such as MOOCs, articles, and application notes.

All useful links are directly accessible.

[Ahmet Yasin CİVAN]

Thank you so much for sharing this comprehensive guide to USB development resources on STM32! This is an invaluable resource for both beginners and experienced developers working with STM32 microcontrollers. The detailed breakdown of available documentation, example projects, and tools will definitely save many hours of searching across different sources. I particularly appreciate how well-organized the information is, making it easy to find exactly what's needed for specific USB implementations. This guide will be a great reference for my future STM32 projects.