USBH internal peripheral

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Applicable for STM32MP13x lines, STM32MP15x lines

1. Article purpose[edit source]

The purpose of this article is to:

  • briefly introduce the USBH peripheral and its main features,
  • indicate the peripheral instances assignment at boot time and their assignment at runtime (including whether instances can be allocated to secure contexts),
  • list the software frameworks and drivers managing the peripheral,
  • explain how to configure the peripheral.

2. Peripheral overview[edit source]

The USBH peripheral is used to interconnect other systems with STM32 MPU devices, using USB standard.

The USBH peripheral is a USB Host controller supporting high-speed (480 Mbit/s) using an EHCI controller, and full- and low- speeds (12 and 1.5 Mbit/s) through OHCI controller.
The USBH peripheral has two physical ports providing a UTMI+ physical interface, mapped on an on-chip 2-port high-speed UTMI+ PHY.
It supports the standard registers used for low- and full-speed operation (OHCI model) and high-speed operation (EHCI model) and the power management feature called Link Power Management (LPM).

The supported standards are:

  • Universal Serial Bus Revision 2.0 Specification[1], Revision 2.0, April 27, 2000
  • USB 2.0 Link Power Management Addendum Engineering Change Notice to the USB 2.0 specification[2], July 16, 2007
  • Enhanced Host Controller Interface Specification for Universal Serial Bus[3], Revision 1.0, March 12, 2002
  • EHCI v1.1 Addendum[4], August 2008
  • Open Host Controller Interface Specification for USB[5], Release 1.0a, September 14, 1999
  • USB 2.0 Transceiver Macrocell Interface (UTMI) Specification[6], Version 1.05, March 29, 2001
  • UTMI+ Specification[7], Revision 1.0, February 25, 2004

Refer to the STM32 MPU reference manuals for the complete list of features, and to the software frameworks and drivers, introduced below, to see which features are implemented.

3. Peripheral usage[edit source]

This chapter is applicable in the scope of the OpenSTLinux BSP running on the Arm® Cortex®-A processor(s), and the STM32CubeMPU Package running on the Arm® Cortex®-M processor.

3.1. Boot time assignment[edit source]

3.1.1. On STM32MP1 series[edit source]

The USBH peripheral is usually not used at boot time. But it may be used by the SSBL (see Boot chain overview), for example to boot a kernel stored on a USB key (mass storage).


Click on the right to expand the legend...

Check boxes illustrate the possible peripheral allocations supported by STM32 MPU Embedded Software:

  • means that the peripheral can be assigned to the given boot time context.
  • means that the peripheral is assigned by default to the given boot time context and that the peripheral is mandatory for the STM32 MPU Embedded Software distribution.
  • means that the peripheral can be assigned to the given boot time context, but this configuration is not supported in STM32 MPU Embedded Software distribution.
  • is used for system peripherals that cannot be unchecked because they are hardware connected in the device.

The present chapter describes STMicroelectronics recommendations or choice of implementation. Additional possibilities might be described in STM32 MPU reference manuals.

Domain Peripheral Boot time allocation Comment
Instance Cortex-A7
secure
(ROM code)
Cortex-A7
secure
(TF-A BL2)
Cortex-A7
non-secure
(U-Boot)
High speed interface USBH (USB Host) USBH (USB Host)

3.2. Runtime assignment[edit source]

3.2.1. On STM32MP13x lines More info.png[edit source]

Click on the right to expand the legend...

STM32MP13 internal peripherals

Check boxes illustrate the possible peripheral allocations supported by STM32 MPU Embedded Software:

  • means that the peripheral can be assigned to the given runtime context.
  • means that the peripheral is assigned by default to the given runtime context and that the peripheral is mandatory for the STM32 MPU Embedded Software distribution.
  • means that the peripheral can be assigned to the given runtime context, but this configuration is not supported in STM32 MPU Embedded Software distribution.
  • is used for system peripherals that cannot be unchecked because they are hardware connected in the device.

Refer to How to assign an internal peripheral to an execution context for more information on how to assign peripherals manually or via STM32CubeMX.
The present chapter describes STMicroelectronics recommendations or choice of implementation. Additional possibilities might be described in STM32MP13 reference manuals.

Domain Peripheral Runtime allocation Comment
Instance Cortex-A7
secure
(OP-TEE)
Cortex-A7
non-secure
(Linux)
High speed interface USBH (USB Host) USBH (USB Host)

3.2.2. On STM32MP15x lines More info.png[edit source]

Click on the right to expand the legend...

STM32MP15 internal peripherals

Check boxes illustrate the possible peripheral allocations supported by STM32 MPU Embedded Software:

  • means that the peripheral can be assigned to the given runtime context.
  • means that the peripheral is assigned by default to the given runtime context and that the peripheral is mandatory for the STM32 MPU Embedded Software distribution.
  • means that the peripheral can be assigned to the given runtime context, but this configuration is not supported in STM32 MPU Embedded Software distribution.
  • is used for system peripherals that cannot be unchecked because they are hardware connected in the device.

Refer to How to assign an internal peripheral to an execution context for more information on how to assign peripherals manually or via STM32CubeMX.
The present chapter describes STMicroelectronics recommendations or choice of implementation. Additional possiblities might be described in STM32MP15 reference manuals.

Domain Peripheral Runtime allocation Comment
Instance Cortex-A7
secure
(OP-TEE)
Cortex-A7
non-secure
(Linux)
Cortex-M4

(STM32Cube)
High speed interface USBH (USB Host) USBH (USB Host)

4. Software frameworks and drivers[edit source]

Below are listed the software frameworks and drivers managing the USBH peripheral for the embedded software components listed in the above tables.

5. How to assign and configure the peripheral[edit source]

The peripheral assignment can be done via the STM32CubeMX graphical tool (and manually completed if needed).
This tool also helps to configure the peripheral:

  • partial device trees (pin control and clock tree) generation for the OpenSTLinux software components,
  • HAL initialization code generation for the STM32CubeMPU Package.

The configuration is applied by the firmware running in the context in which the peripheral is assigned.

For Linux kernel and U-boot configuration, please refer to USBH device tree configuration.

6. References[edit source]