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Open source Cortex-M3 board supports Arduino and FreeRTOS

Sep 9, 2016 — by Eric Brown — 1,698 views

The USB-enabled 55 x 25mm “Explore M3” board is based on NXP’s LPC1768 Cortex-M3 MCU, and supports Arduino IDE, FreeRTOS, and bare metal development.

Bangalore India-based startup Explore Embedded has soared past its exceptionally modest $700 CrowdSupply funding goal for its Explore M3 development board. Early bird packages are gone, but you can still buy in for $19 through Oct. 13, with volume discounts. The Explore M3 is also available with a $20 Soda Debug Adapter and a $49 ARM Starter Kit. Shipments are due Nov. 15.

Explore M3

Explore M3 Robot

The open source, 55 x 25mm Explore M3 expands upon NXP’s 100MHz, Cortex-M3 based LPC1768 microcontroller. The LPC1768 also forms the basis for NXP’s own OM11043 ARM Mbed LPC1768 board reference design.

According to an email from Explore Embedded co-founder Sandeep Patil, the Explore M3 does not use NXP’s design, which differs primarily in the fact that the OM11043 uses a separate ASIC for the USB controller. By contrast, the Explore M3 uses a native micro-USB 2.0 port, which Patil says is cheaper. In addition, the “Explore M3 is completely open source hardware and design,” he adds, suggesting that NXP’s board is not.

Another big difference is that the NXP OM11043 board implements ARM’s Mbed operating system for Cortex MCUs. In contrast, the Explore M3 is designed for FreeRTOS, and also supports Arduino IDE and bare metal programming environments such as ARM-GCC, Ellipse, or toolchains like Kiel or Co-IDE.

Presumably you can also use Mbed or other RTOSes. The device ships with FreeRTOS support “and numerous examples on basics of how to use an RTOS in a project,” says the Crowd Supply page. The board is available with more than 50 tutorials for each of the three main development environments.

Explore M3 pinout
(click image to enlarge)

Explore M3 offers 64KB of RAM and 512KB of flash memory (integrated within the LPC1769), and offers a micro-USB 2.0 full-speed device/host/OTG port, along with a variety of “breadboard friendly” 0.1-inch headers. The board’s I/O, again based on functions within the LPC1769 MCU, includes 38x GPIOs, 4x UARTs, 2x CAN, 2x SPI, 2x I2C, 6x PWM, 5x 12-bit ADC, and a DAC. You also get a pair of interrupt pins, an I2S audio interface, a virtual COM port, and a JTAG/SWD debug port.

Explore M3 schematic (left) and NXP LPC1769 block diagram
(click images to enlarge)

The debug port hooks up to the optional open source “Soda” debug adapter (shown below) or other debug adapters. “We have successfully tested Soda to work with Kiel, and we are working on making it work with Eclipse and ARM GCC,” says Explore Embedded.

Soda debug adapter (left) and ARM Starter Kit
(click images to enlarge)

The optional ARM Starter Kit “equips you with all the components to complete most the tutorials in both the Arduino Series and the Bare Metal Series,” says the company. The kit includes an Explore M3 along with a mini-breadboard, a microSD breakout, a DC motor, and a 128 x 64 OLED display. There are also a variety of IoT-oriented sensors, relays, resistors, jumper wires, LEDs, cables, switches, buzzers, and more.

Explore M3’s cousin: Explore Cortex M3

An earlier, and very similar version of the board called the Explore Cortex M3 is listed for sale on Explore Embedded’s website for 1,499 R’s (about $22). The board has a different appearance, more GPIOs, and other extras.

Further information

The Explore M3 is available on Crowd Supply through Oct. 13 for $19, with volume discounts of $35 (qty. 2) and $90 (qty. 5). There’s also a $20 Soda Debug Adapter and a $49 ARM Starter Kit. All shipments are due Nov. 15. More information may be found at the Explore M3 Crowd Supply page and Explore Embedded website. The board’s Github repository is here.

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One response to “Open source Cortex-M3 board supports Arduino and FreeRTOS”

  1. Max says:

    In the world of low-single-digit-priced WiFi capable modules that’s a whole lot of money for a Cortex-M class chip on a breakout PCB.

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