This little keychain is composed of an Attiny85 (SOIC 8), a button on the IO2 pin (pin 7), a CR2032 battery slot and 7 leds. With this device, you can simulate a dice, and with deep sleep mode, the keychain will work for many months.

To program this device you can use my Attiny Uploader with SOIC clamp.

How to program the board:

Arduino IDE board manager:
ATtiny25/45/85

VSCode platformio.ini:

[env:attiny85]

platform = atmelavr

board = attiny85

framework = arduino

upload_protocol = stk500v1

upload_flags =

-P$UPLOAD_PORT

-b$UPLOAD_SPEED

upload_port = //dev/cu.usbmodem1301

upload_speed = 19200