Usblinky: Unterschied zwischen den Versionen

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===Pitfalls and lessons learned ===

Adafruit trinket

===Adafruit trinket===

~~pinout differences in trinket and digispark design~~

Adafruit built another bootloader that uses a similar trick than micronucleus.

They speak USB over vUSB but enumerate the device as a usbtiny programmer.

The arduino sees a programmer and progremms the ATTINY85 as a target, when it actually overwrites its own FLASH with the user program.

I liked that nifty approach and used the Trinket bootloader when i started this project.

But then i read that adafruit does not wnt you to use their USB ID in a product that you sell.

I contacted them but got no meaningful reply, only a standardized answer that i should come back once my product launched.

Later on i found out that the bootloader on the trinket is fragile.

Under some special circumstances it can happen that the bootloader falsy triggers and the FLASH on the MCU is damaged and it can not be programmed any more over USB.

That was the point that i took a closer look at the micronucleus bootloader.

This bootloader is significantly smaller (2k versus 3.5k) and the code is much more straight forward than the trinket bootloader.

The drawback is that you need to modify the arduino environment, but there are packages available for that.

When I used the usblinky as a BUTTON for the selfiebooth setup i realized that the pinout is inversed on the trinket.

D+ and D- are switched on the MCU side.

In theory not a big deal, but a lot of libraries that are available for the digispark project (for example the USB keyboard emulation) has this pinout hardcoded and I needed to modify the .cpp files in the Arduino environment to make that work.

Future versions of USBlinky have the pins swapped as on the original digispark design.

== Alternate usecases ==