In addition to being a 4-port USB 2 High-Speed hub, this Programmable USB hub is also:

• A CircuitPython based development board.
• A bridge between your computer and I²C (via Sparkfun Qwiic connectors), GPIO, and SPI (via its mikroBUS header).
• A power supply, providing 6 A of 5 V power to downstream devices and 13 mA resolution monitoring (per-port). Port power is individually limitable and switchable.
• A USB to TTL Serial adapter.
• A flexible embedded electronics test and development tool. USB data pairs are individually switchable, allowing you to emulate device removal and insertion via software.
• Mountable.
• Functionally flexible. Open source python drivers on the upstream host and Python firmware on the internal MCU allow the behavior of this USB hub to be easily changed to suit your application and environment.

The Capable Robot Programmable USB hub is housed in a robust extruded aluminum enclosure.

Internally mounted LED light pipes direct status information from 10 RGB LEDs to the front panel for easy observation of hub state.

The rear of the enclosure exposes the upstream USB connection and a USB port to re-program and communicate with the internal MCU. Also exposed are two I²C buses (via Sparkfun Qwiic connectors), the Programmable USB hub’s UART, and 2x GPIO. Input power is provided to the hub by a locking Molex connector.

Features and Specifications

• USB2 High-Speed Hub
  • 4x USB2 High Speed (480 mbps) downstream ports
  • 1x USB2 High Speed (480 mbps) upstream port
  • 5th endpoint on USB hub exposes I²C, SPI, UART, and 2x GPIO
  • Data lines to each USB port can be disconnected via software commands. This allows errant USB devices to be "unplugged" virtually and re-enumerated.
  • USB digital signals can be boosted to help drive long cables.
• Power Monitoring & Control
  • 5 V power on each downstream port can be individually turned on and off
  • Monitor the power consumed by each port at up to 200 Hz at a resolution of 13 mA
  • Adjustable (per-port) current limits between 0.5 A and 2.6 A
  • Onboard regulator supports 12 V to 24 V power input and generates 6 A of 5 V power for downstream USB devices; both voltages can be monitored by the internal MCU. No power is drawn from the upstream USB port.
  • Input power is protected from over-voltage events and reverse-polarity connection.
• Physical IO
  • mikroBUS header to add additional sensors and connectivity. Solder jumpers allow the UART and SPI pins to connect to either the USB hub or the MCU.
  • JST GH connector with UART and 2x GPIO, controlled by the USB hub.
  • 2x Sparkfun Qwiic connectors enable easy attachment of I²C sensors to the USB hub or to the internal MCU.
  • 5x RGB status LEDs to visualize port power draw
  • 5x RGB status LEDs to visualize port connection types

Data and Power LEDs showing Hub State.

With the default firmware behavior, the Data LEDs show per-port data state with the following meaning:

• White : High speed device detected
• Green : Full speed device detected
• Blue : Low speed device detected
• Off : No downstream device detected
• Orange : Port data lines internally disabled / disconnected

Likewise, the Power LEDs show per-port power draw in blue, with higher port power displayed as a brighter blue. Ports which have power turned off are lit orange and any over-current condition is shown by lighting the LED red.

The CircuitPython firmware is easy to modify to change how these RGB LEDs display Hub state.

Control and Monitor with Open Source Python Drivers

The Programmable USB Hub is proudly open source. You can use MIT-licensed Python drivers to control and monitor your USB Hub the way you want to. The Hub can be easily integrated into hardware-in-the-loop (HITL) test systems and its’ in-built IO expansion allows the Hub itself to control or stimulate the Device Under Test (DUT). You can also automate testing of embedded USB devices - simulating USB unplug events and unexpected loss of USB power. Use the upstream USB port or the MCU USB port to control and monitor the USB hub.

Runs Adafruit CircuitPython

An ATSAMD51 microcontroller configures the USB Hub IC and is available for you to reprogram to change the behavior of your hub. The microcontroller ships with open source CircuitPython firmware, which is updatable over the MCU USB connector. No drivers or reflashing hardware is needed — Python firmware shows up as files on a small flash hard drive when connected to your computer and code can be immediately edited.

Physically and Logically Expandable

USB Hub controlling and I2C OLED Display from the upstream host.

Here, CircuitPython software running on the upstream Mac OS Host (not the internal MCU) is controlling this OLED display, which is attached to the Hub via the rear Qwiic I²C port. The Driver Repository includes a Bridge, allowing unmodified CircuitPython libraries to run on Mac OS, Linux, & Windows and communicate with devices attached to the Hub.

Alternatively, the MCU’s CircuitPython firmware can be modified to communicate with external sensors or devices to create automatic behaviors which do not require host driver control.

IMU sensor installed into MikroBUS.

Here, an IMU board has been installed into the mikroBUS port and the built-in CircuitPython firmware changed to detect and respond to tap events.

How the Hub responds to these events is up to you, instead of displaying text on the OLED screen, the hub could:

• Power cycle a downstream port
• Disconnect data lines to a downstream port
• Change current limits of downstream ports
• Change the behavior of the front panel RGB LEDs
• Control external I²C devices

Robust Design

The Programmable USB Hub is designed to be durable and robust. The OEM version (board only) has corner mounting holes for easy integration into a custom enclosure. The Micro-USB connectors are reinforced, and the IO is protected from ESD strikes (exact specification TBD).

The locking input power connector features reverse polarity protection and over-voltage protection. The extruded aluminum enclosure for the Hub can be fitted with optional rubber bumper end caps or optional flange mounts.

USB Hub with optional Rubber Bumpers (left) & Mounting Flanges (right).

Support & Documentation

Currently, there are two GitHub repositories which have relevant software and documentation for the USB Hub.

• The Firmware Repository holds the CircuitPython-based firmware which configures the main USB Hub chip upon boot, and runs the monitoring loop which controls the RGB LEDs on the Hub's front panel. This repository is a great starting place to customize the automatic behavior of your USB Hub.
• The Driver Repository holds a host-side library which allows communication and control of an attached Hub. The repository includes example Python scripts & programs which allow you to read & control Port Data State, Port Power, and other functions. The repository also includes a Bridge which allows unmodified CircuitPython code to run on the host computer and communicate with I²C devices attached to the Hub.

Please open a GitHub issue if you have a suggestion for the product or run into any problems using it, or use the “Ask a Question” link below.

If you have a question about ordering, paying, or shipping, please refer to The Crowd Supply Guide.

Comparisons

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