Hi guys! The creator here (full disclosure
)
Jim,
I like blinkenlights too! I grew up around mainframes with rows and rows of them on the control panel, so DeDe is a bit of a throwback to those days.
The LEDs are driven directly from the buffers without any RC filtering.
The original purpose was for it to be a debugging tool, but after adding the prototyping area and rethinking it, I think it a great educational tool for beginners too. One can learn a lot of programming when you couple 20 pairs of LEDs and a serial port (the "no additional components required" case), and even more just by adding some pushbuttons, sensors, servos, etc. as people learn more.
Cyber,
I agree that you can don't have to have something like DeDe to attach test equipment, but it does make it easier. I used a logic probe for Arduino projects too before I built this (and still do on other boards), but you have to find a place to clip the power leads to (and sometimes have to solder a pin or wire to the PCB to do so), and trying to probe a GPIO while interacting with the project (like pushing buttons on it, for example) isn't always easy. At least with DeDe, it's like having 21 logic probes always attached and it's easy to get an idea what's happening (or not happening) at a glance.
I stand by the 1mS pulse visibility. It was a somewhat arbitrary goal, but I figured someone would ask. Ironically, it's easier to see the 1mS pulses with my eyes than it was to capture on video (think Nyquist rate). I had to take several seconds of video to get a snippet where the camera captured it. It's easier to see on the red LEDs thank the green, partially because the red LEDs are driven a little harder than the green, and I think the contrast between the diffused lens and the ON state is better for red than it is for green.
You're definitely not going to decode any kind of serial comms with the LEDs, but at least you can see if there's activity or not. If you're sketch is supposed to read from an RTC module, and you don't see the I2C/SPI lines toggling, then you know something's wrong just by glancing at the LEDs.
I use a divide and conquer approach when debugging, and DeDe helps with that. If I have a sketch that reads a pushbutton and take an action based on it, for a simplified example, and it's not working, I can see if the LED for that pushbutton toggles when I press the button. If it doesn't, I should probably look at the button. If it does, then I need to look at the code. Similarly for an output, I can see if the output is turning on or not...if it is, then I need to look at whatever piece of hardware I'm trying to drive. If the LED isn't toggling (or maybe it's the wrong one), then I need to look at the code.
Anyhay, thanks for at least checking it out!
Cheers!!