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Review: mbed NXP LPC1768

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The mbed is an interesting board to play with. It took only minutes to write my first program using the online development environment. (Just for fun, I had it flash "Tiffany Yep" in binary on its 4 LEDs. My first program for it had to be special!)

* Easy to set up.
* 96MHz of CPU that fits on a breadboard.
* The Ethernet port is actually 100Mbit.
* Very flexible I/O

* USB is only 1.1.
* No official support for standalone compiler.
* Not all I/Os on chip are usable.
* On mine, the USB port is poorly soldered.
* Poor documentation.
* 512kB Flash and 64kB RAM is very limited.
* Inefficient linear regulators.

I haven't got to play with most of its features, but here's what I figured out:
* To use the Ethernet port, connect a 0.1uF capacitor in series with each of the 4 Ethernet I/Os (one per line), then connect them to the RJ45. Ground the other 4 RJ45 pins unless you're using PoE.
* The IF+/- are connected in parallel with the USB port.

I'm planning to use it for my ECEN 489 networking class project. I'm thinking something exotic like a network-connected oscilloscope, logic analyzer, or spectrum analyzer.


--- Quote from: NiHaoMike on October 06, 2010, 05:00:57 am ---

* 512kB Flash and 64kB RAM is very limited.
* Inefficient linear regulators.

--- End quote ---

Limited? You would have hated programming in the 1980s and 1990s then! This isn't a Windows machine which has huge library overheads and tons of graphics and sound.

Linear regs are often MORE efficient than switching regs on low power systems. Switching regs require a certain baseload current to operate, and draw an amount of power themselves to operate the switcher. Linear regs scale with the load (and of course voltage drop). Don't forget that an ARM core draws in the sub-milliamp region when not driving LEDs etc.


I don't understand all the Tiffany Yep references.

Its his girlfriend or something.  You will just learn to look over it.


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