Friday, July 28, 2017

Using OpenScad to design Adafruit Trellis casing

Hey there! Spent sometime using OpenScad - 3d design tool. All 3d objects designed programmatically. It was a bit of a pain. I'll probably stick with something as Autodesk Fusion 360 in the future.

The advantage of OpenScad is that you can parametarize your 3d model. For example Trellis box has number of buttons parametirized: you can easily change from 4x4 to 8x4 or 8x8 or other... It as well has height, thickness, etc parameterized. It means that adjusting the model size should be quite easy.

You can use OpenScad to export design into STL and 3d print it.

Below is the screen capture from OpenScad for Trellis 3d model. It as well available at github link.

And here is one of the earlier version print out combined with trellis:

Monday, July 24, 2017

Adafruit Trellis must have 30 ms delay between key reads

A bit disapointed by the Trellis requirement to have delay (30) ms in the Arduino loop (default is 30, it worked on 25ms setting). Apparently Trellis is using HT16K33 that in order to scan 39 key matrics (even Trellis exposing 16 keys) according to specs requires 20ms to complete the whole internal scan loop. The delay may be noticable in applications that require faster response than 20ms e.g. music instruments or gaming controllers.

BTW. This blog post explains details about HT16K33