mbed: sense & simplicity

If you ever tried to setup a microcontroller development environment you know how difficult this can be. The more powerful the controller, the more complicated the tools. Even often expensive tools require lots of time to get them going. Setting the paths right, creating linker files, writing make files, understanding compiler options, it all takes a lot of effort and headache and three months later you can’t possibly remember how it all works.

Now NXP comes to the rescue for folks who need to work with ARM controllers: the mbed module with online development tools. The module, about the size of a matchbox, contains an LPC2368 ARM7 microcontroller and a USB port. There is also ‘some’ I/O: Ethernet, USB, CAN, UART (3x), SPI (2x), I2C (2x), 6 analogue inputs, 6 PWM outputs and some other stuff. All this, including the passive components for USB and Ethernet (you only have to hook up a connector), is available on a 2x 20 pin connector that fits on a breadboard. For the moment there is only one model, but a Cortex version has already been announced.

So how does this work? Easy: connect the module with a USB cable to a computer with Internet access; the OS is not so important as long as there is an Internet browser. De computer recognizes the module as a mass storage device with an HTML file on it. Open this file in the browser and click the link that allows you to open an account. (Don’t worry, no difficult questions asked.) Once logged in follow the compiler link and start writing C code. Compile it, without errors of course, and download the executable directly to the mbed USB disk. Press the Big Blue Reset Button in the middle of the board to let your program run. It is that easy!

This sounds maybe like a nice demo, but it is much more. The compiler comes with many libraries that make programming very easy. It has an Arduino feel with functions like DigitalIn and AnalogOut, but f.i. SPI, I2C and a complete file system are available too. Libraries for Ethernet and USB are under construction, mbed is still in the beta stage. The API is very well documented and the mbed website is loaded with information, tutorials and examples. Debugging is possible too because the mbed module can function as a double USB peripheral: mass storage device and serial port at the same time!