One product very similar to the Teensy USB development board are the open-source (hardware and software) avropendous boards, which now seem to be available in a DIP form factor ala the Teensy board, at a similarly low price. The AVRopendous-DIP ($22) uses the same AT90USB162 as the Teensy board, and allows selecting 5v or 3v3 operation via a jumper. There seem to be some more recent additions to the AVRopendous-DIP family, in particular the ATmega32U4-based AVRopendous2-DIP ($29), the AT90USB646-based AVRopendous3D-DIP ($32), and the AT90USB647-based AVRopendous3H-DIP (not yet for sale?) The 3D and 3H variants provide a more powerful microcontroller, and the 3H variant adds the ability to function in USB host or OTG modes. Not to be dismissed however, the AVRopendous2-DIP has more than double the memory (both flash and RAM) of the AT90USB162-based products and can supply the most current (450ma) at 3.3v.
Most of the things I’m interested in interfacing these days is 3v3, which tend to require extra components to safely interface to a 5v device like the Teensy board. I looked into what it would take to modify the Teensy operate at 3v3, it should just barely be doable with some very delicate soldering. (I had hoped there was some bit of the Teensy design that would make this trivial, like a 0-ohm resistor I could move to make it work at 3.3v. Alas, no such luck…) The AVRopendous design does make this trivial, with it’s jumper-selectable voltage. It’s not a perfect substitution since the AVRopendous lacks the compact bootloader that the Teensy ships with (although made up for by additional flash memory on the AVRopendous2-DIP), and the device has a slower clock (8mhz) that is required to work at both voltages. However, the $25 ATmega32U4-based AVRopendous2-DIPnh (with no headers) option is a deal I couldn’t pass up… Expect to see some pix and a review here when it arrives.
Post a Comment