If you wish to display useful information automatically retrieved from the internet 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 the USB port of the OpenWrt router you can see in the picture on the left.

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 do was to pick an Atmel AVR microcontroller, compile the firmware 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.

The USB module requires very little hardware as you can see in the picture below.

To take full advantage of the I²C bus an MCP9808 temperature sensor was added later. This sensor is not in the pictures.

The slideshow above shows the assembly of the display and the USB module into the livebox router.

The OpenWrt firmware was compiled with the usbcore and i2c_tiny_usb modules. They take care of controlling USB and I²C.

All documentation of this project like Eagle schematics and layouts can be found here.