Open source i.MX6 SBC offers Pi and Arduino expansion
Mar 2, 2016 — by Eric Brown 2,812 viewsFedevel released an open source design for a Linux-ready, i.MX6-based “OpenRex” SBC with a Cortex-M3 MCU, a stackable design, and Arduino and Pi expansion.
Most embedded board vendors announce a board for pre-sale, then wait to post whatever documentation they intend to release when they finally ship the board. Slovakia-based training and embedded firm Fedevel and its manufacturing partner Voipac have taken a different tack. In conjunction with their announcement of the open source OpenRex SBC, they released full documentation for the board, including complete Altium design files with schematic & PCB plus full manufacturing documentation.
Instead of opening pre-sales on the open source, Linux-supported OpenRex, which is due to ship in Q2, Fedevel is asking interested parties to fill out a form asking how much they would pay for the SBC. Options range from up to $50 to more than $200.


OpenRex, real (left) and imagined
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The first publicly sold board from Fedevel and Voipac was a circa-2013 iMX6 Rex COM, which was available with a baseboard and full development kit. With the OpenRex, Fedevel has once again tapped the NXP/Freescale i.MX6 system-on-chip with up to four Cortex-A9 cores. This time, however, it’s a monolithic SBC instead of a sandwich-style combo.
The OpenRex differs from the iMX6 Rex COM/baseboard combo in that it integrates a Raspberry Pi compatible 40-pin expansion connector. It also features a Cortex-M3-based NXP LPC1345FHN33 microcontroller to enable Arduino signaling via an Arduino type header.

Renders of some of OpenRex’s nine PCB layers
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As with the iMX6 Rex COM and baseboard, the main goal is to provide a suitable embedded Linux training board for Fedevel’s online Fedevel Academy Schematic & PCB Design Courses. Fedevel Academy boasts students from 75 countries around the world, including the U.S., as well as clients including 3DR, 3M, Altera, Bosch, MIT, NASA, Nintendo, Siemens, and Tesla.


OpenRex block diagram (left) and stackable board design
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The 95 x 70mm OpenRex features a stackable design that enables students and other hackers to design add-on boards. Initially, there will be a top-mounted add-on board with its own Raspberry Pi compatible connector, designed for use with a single-core Solo i.MX6. This is aimed at designs with “no or low profile heatsink,” says Fedevel. A larger bottom-mounted board is also in development, suggesting the use of OpenRex in multiple-board, PC/104-style stacks.


OpenRex top and bottom details
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The OpenRex supports up to 4GB of RAM, and offers microSD and SATA storage. A Gigabit Ethernet port is provided, but wireless is limited to a PCIe expansion interface supported with a micro SIM card slot.
The OpenRex ships with an HDMI port, a touchscreen controller, and audio I/O. Optional features include a choice between an LVDS display interface or a Pi-compatible camera input, as well as a choice between an RGB display interface and a Parallel CSI camera input.

OpenRex front view
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The SBC is equipped with a pair of USB ports, plus a micro-USB OTG port, and there are CAN and debug ports. The Arduino and 40-pin Pi connectors open up many more GPIOs and other interfaces. The OpenRex offers sensors including motion, humidity, and temperature, and supplies numerous user-controlled buttons and LEDs.
Specifications listed for the OpenRex SBC include:
- Processor — NXP i.MX6 Quad (4x Cortex-A9 cores @ up to 1.2GHz); Vivante 2D/3DGPU, video accelerators etc.; NXP LPC13xx (default: LPC1345FHN33)
- Memory/storage:
- Up to 4GB soldered DDR3-1066 RAM (533MHz)
- Up to 128Mb SPI flash, I2C EEPROM
- MicroSD slot
- SATA connector
- Display/multimedia:
- HDMI output for up to 2048 x 1536
- LVDS or differential, Pi-compatible camera input
- RGB Parallel display or Parallel CSI camera input
- 3.5mm audio in/out jack
- Touchscreen connector (via LPC13xx) or optional 4x analog input
- Networking — Gigabit Ethernet port
- Other I/O:
- 2x USB ports
- Micro-USB OTG port with power support
- CAN
- UART debug console (FTDI compatible)
- IR
- Arduino-compatible header — 4x analog input, 3x GPIO, I2C, CAN, USB
- Raspberry Pi-compatible header — 2x I2C, 2x UART, CAN TX/RX, 2x SPI, 3x GPIO/PWM
- Expansion — mini-PCIe slot with x1 PCIe and USB, plus a micro-SIM Card slot
- Other features — accelerometer, compass, gyro; humidity and temperature sensors; “8+2x” user LEDs; power, SD, USB hub LEDs; reset button; 3x user buttons
- Power — 5VDC power jack or micro-USB; PMIC regulator
- Dimensions — 95 x 70mm
- Operating system — Linux
Further information
The OpenRex schematics and other open source design files are available for free download. Interested customers can register for notification to buy the board, which is expected to ship from Fedevel partner Voipac in the second quarter at a yet to be determined price. More information may be found at Fedevel’s OpenRex product page.
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