Ondre's spot on the web

Rainy days, withering flowers, getting colder every morning. Is the summer almost over? Maybe it’s time to move to the southern hemisphere!

Many years ago I got the SHT11, a digital humidity and temperature sensor, as a free sample from Sensirion. Unfortunately they are not available as samples anymore. You have to pay about 20 EUR at RS-Online or Farnell to get one.

I’ve designed a small circuit for interfacing the sensor with an Atmel microcontroller and the PC via RS-232.

The firmware running on an Atmel AT90S2313 polls the sensor approximately every two seconds and acquires 12- and 14-bit long humidity and temperature values. The numbers are written as hex values to the serial interface.
A tiny C-program running on the PC reads the numbers from the serial interface, translates them into human-readable data and eventually sends them to stdout.

The firmware was compiled using avr-gcc. Consider that the PC software is available for Linux only.

Download the SHT11 project folder here.

Note: This was one of my first microcontroller projects. I used obsolete functions like “outb”. The source code won’t compile with recent versions of the avr-gcc. Maybe someone can post his updated sourcecode here!

Ondre has not produced any content for his new website yet, but it’s all set up and running. Still need some more time to figure out all about the wordpress stuff.