the arduino, itself a clone, gave way to many other variations.
most clones are only about cost cutting but some do offer unique additions. here is a growing list of such.
note: there are many boards that use the arduino bootloader and piggyback on its IDE.
i'm currently aiming for those that stick to the form and function of the original but extend it in some ways.
Robodyn nano v3
comes in both 168 and 328 versions. china cheap at ~2.2$ in bulk
- dedicated 12Mhz crystal clock for the CH340G USB2serial chip, for reliable higher baud rates
- voltage regulators for both 5V and 3V3 (800mA)
- in the original arduino the 3v3 output voltage pin comes from the FTDI chip and is limited to 30mA, CH340 on most clones can deliver ~25mA
- micro usb instead of usb B
- auto resettable fuse to protect USB from overcharge
- see comparison for no-name clones (pic)
not completely open as no gerber files or design files, schematics and sizes are available.
some intresting blog on the diff between versions
- 12 vs 12E module
- "FCC" shield vs bareback
- AND serial to usb solution
- The main difference is USB to UART bridge IC. V0.9 uses ch340G driver, but have many problems on MAC, so we released V1.0 which uses CP2102 and have a good performance. comment
- "offical" diffs
an early favorite mega clone, unfortunately keeps the price level of western suppliers.
- form factor
- Selectable 5V/3.3V operation schematic bit
open source - yes, see bottom of wiki for eagle files