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Baseboard morphs BeagleBone Black into 3.5-inch SBC

Apr 24, 2014 — by Eric Brown 3,909 views

[Updated 5:00PM] — A new Kickstarter project aims to fund a 3.5-inch SBC-sized baseboard that adapts a BeagleBone Black and/or Raspberry Pi for use in real-world applications.

Oregon-based APlus Mobile came up with the idea for the “MotherBone PiOne” while trying to add peripherals to the Linux-ready BeagleBone Black and Raspberry Pi Model B single board computers. Faced with the boards’ limitations relative to “real world expandability,” especially in regard to the BeagleBone Black’s power isolation issues, the company decided to develop a baseboard aimed at solving those problems for both hacker SBCs.

Two views of the MotherBone PiOne
(click images to enlarge)

The BeagleBone Black manual, for example, cautions users to not apply voltage to any I/O pin when power is not supplied, or connect 5V logic level signals to pins. “Since we were required to provide some kind of voltage isolation in order to connect the BeagleBone Black to any external devices, we figured everyone else would need some form of isolation as well,” explains APlus on the Kickstarter page for its new project.

MotherBone PiOne with BeagleBone Black installed (left), and cabled to Raspberry Pi (right)
(click images to enlarge)

As seen in the photos above, you plug the BeagleBone Black (upside-down) directly into a pair of headers on the MotherBone PiOne board and secure it with four screws to standoffs, treating it more like a computer-on-module (COM) than an SBC. The Raspberry Pi, meanwhile, has second class status: integrating it into the system requires connecting a ribbon cable between its I/O expansion header and a similar header on the baseboard, and it’s left dangling alongside.

The 3.5-inch SBC form-factor MotherBone PiOne protects all pins on either hacker SBC with opto-isolators and voltage level translators, expanding and isolating all default configuration pins that are not already being used by the BeagleBone Black’s internal resources. The board also implements two different on-board communication links between the two hacker-SBCs, enabling them to be operated individually or simultaneously. These include a jumper-selectable “BonePi Bridge” that uses null modem and I2C communications.


Other major components include multiple on-board switching power supplies for powering the array from a wide, 7.5-36VDC input range. There’s also a four-port USB hub with coastline connectors, plus support for expansion capes and shields.

Specifications listed for the MotherBone PiOne include:

  • Processor/memory — via BB Black and/or RasPi
  • Ports accessible directly from BB Black or RasPi:
    • 10/100 Ethernet port
    • HDMI port
  • I/O functions supplied by the MotherBone PiOne board:
    • Four-port USB hub with extended current capability (usable by BB Black and RasPi)
    • “BonePi Bridge” I2C and null modem links and relay access for Pi (jumper selectable)
    • Serial console (UART0) for BB Black J1 serial interface on BonePi Bridge
    • 16-bit GPIO (I2C Slave) with 5V TTL level
    • 5-pin I2C master access for BB Black and Pi, with additional 5-pin I2C2 voltage isolated port for BB Black
    • 5x solid state relays for AC, DC, and analog switching
    • 7x wide-range analog voltage inputs with trim adjust for voltage range select
    • 2x high-current, open drain MOSFET PWM outputs
    • 2x fully opto-isolated +5V TTL voltage level translated UART connections
    • Opto-isolated 5V MIDI in and out
    • Expansion cape EEPROM with address select for BB Black
  • Other features:
    • RasPi I/O pass-through header
    • Power and rest buttons
    • power LED
  • Power — 7.5-36VDC input range
  • Operating temperature — 0 to 60°C
  • Dimensions — 5.8 x 4.0 inches; 3.5-inch SBC form-factor
  • Operating system — Linux

Here’s a brief YouTube video showing how the two hacker-SBC work with the MotherBone PiOne:

Quick MotherBone PiOne demo

Further information

The MotherBone PiOne funding project is only a fraction of the way toward its $60,000 goal, but has until May 18 to get the job done. Meanwhile, you can pick-up a pre-production board for $225, due in July, or a production board for $235, due in August, from the funding project’s Kickstarter page. Additionally, a $140 “bare bones” version is available for August delivery; it omits the baseboard’s three UARTs (two serial, one MIDI) as well as the three screw terminal blocks on the side opposite the USB hub’s connectors. These prices don’t include the Raspberry Pi or BeagleBone Black SBCs.

More information may be found at the MotherBone PiOne Kickstarter page as well as at APlus Mobile’s MotherBone PiOne product page.

(advertise here)

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5 responses to “Baseboard morphs BeagleBone Black into 3.5-inch SBC”

  1. Timothy says:

    There is now a low cost “barebone” MotherBone PiOne option on the Kickstarter page for $140. It has depopulated the three UART’s, so no MIDI or Serial ports.

  2. Amy Ciesielka says:

    I would like to point out that the Raspberry Pi connection on MotherBone PiOne via ribbon cable (aka: “second class status”) is also compatible with all of the Raspberry Pi variants that use a Raspberry Pi compatible header. Because the variants are different sizes and shapes, the MotherBone PiOne allows remote mounting of all the Pi modules in various chassis.

  3. Timothy says:

    Also lower international shipping rates (half) now on MotherBone PiOne on kickstarter.

  4. Tedy says:

    You have freebuild images Debian OS with reading MIDI and plus i2s audio dac for beaglebone and this board

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