Thanks for all the feedback and suggestions so far on the tinyK20 project! I’m proud to present the next iteration of the universal microcontroller & debugger board based on the Freescale Kinetis K20 USB microcontroller:
Changes from the earlier version (see “tinyK20 Open Source ARM Debug/Universal Board – First Prototypes“):
- Replaced the K20 crystal with one having a smaller footprint.
- Added Micro SD card socket on the back (same socket as on the FRDM-K64F or FRDM-K22F).
- Because SD cards can draw more than the 120 mA the K20 internal 3.3V provided, there is a footprint on the backside of the board to add an extra DC-DC converter.
- Moved reset button and headers.
- First version with transparent enclosure.
The new version includes a micro-SD card socket on the bottom side of the board. Because the 3.3V DC-DC converter of the K20 only can drive 120 mA, there is a footprint on the back to add a 5-to-3.3V DC-DC converter.
If the breakable debug part of the board is removed, the SD card can be easily removed. But it works well with the ‘full’ board, but of course is not that user-friendly.
One thing we will probably do for the first ‘production’ run is to move the capacitor under the SD card. Personally, I prefer the ‘USB cable’ version: I have a mini-USB cable already, that makes it easier to move the board, say to the robot to be programmed, as the SWD flat cable should be only a few centimeters long. My vision is to use a transparent shrink-tubing around the board instead of a special case. What do you think? Which version would you prefer: the ‘cable’ or the ‘thumb’ version?
Happy tinying 🙂
- First concept: https://mcuoneclipse.com/2015/04/21/proof-of-concept-open-source-arm-swd-debug-and-general-purpose-board/
- First prototype boards: https://mcuoneclipse.com/2015/05/17/tinyk20-open-source-arm-debuguniversal-board-first-prototypes/
- Thumb drive enclosure: https://mcuoneclipse.com/2015/05/20/tinyk20-usb-thumb-drive-enclosure/
- Material on GitHub: https://github.com/ErichStyger/mcuoneclipse/tree/master/tinyK20