|USB I2C character display|
If you wish useful information automatically retrieved from the internet and shown on a display you need a
display and you need to connect it to the internet. In this case the display is a Tsingtek 2 line x 20 characters
OLED display and the way I connected it to the internet is through USB and an OpenWrt router.
This HCS2022-Y-EH display has an I2C interface so cutting edge technology is needed to hook it up to USB. Fortunately Till Harbaum developed the firmware code needed. The only thing left to be done was to pick an Atmel AVR microcontroller, compile the firmware for it and flash it. My choice was the ATtiny45-20PU for its characteristics in terms of flash size, speed, package and its built-in oscillator that is stable enough for this application.
That leaves very little to be implemented in hardware: two caps and five resistors of which only three were mounted, to be specific.
This module was mounted to the display which was mounted to a livebox router running OpenWrt firmware. The firmware was compiled with the usbcore and i2c_tiny_usb modules. They take care of controlling USB and I2C.