micronucleus

Could have been simpler still. You can read the internal temperature of the ATiny85 [1]. You can also get the ATiny85 to speak USB and even be flashed via USB via the micronucleus bootloader [2]. [1] https://andrey.mikhalchuk.com/2011/06/20/reading-attiny85452... [2] https://github.com/micronucleus/micronucleus

You can actually bit-bang low speed USB on Arduino [0]. There is even a bootloader [1] for ATtiny visible to host as HID USB device. It is obviously not compatible with Arduino, but those tiny boards look too cute to ignore [2]. Also, you can use USB port both for downloading firmware and your application. [0] https://github.com/obdev/v-usb [1] https://github.com/micronucleus/micronucleus [2] https://cpldcpu.wordpress.com/2014/04/25/the-nanite-85/

The Digispark[1] and its clones use the ATTINY85 and offer flashing over USB via the Micronucleus bootloader[2] using V-USB[3]. It comes at the cost of a significant chunk of flash storage, but the convenience is excellent. Plus, V-USB support means you can emulate all sorts of USB devices. I've used it to build a DIY NES controller adapter, but it's commonly used as a cheap Rubber Ducky[4]. For projects where USB interfacing makes sense, it can be a good fit. 1: http://digistump.com/products/1 2: https://github.com/micronucleus/micronucleus 3: https://www.obdev.at/products/vusb/index.html 4: https://shop.hak5.org/products/usb-rubber-ducky-deluxe