Such multi-purpose device is a nice example of of using microcontroller for combined tasks.
The intent was to use radio module (KDC-2092) from Kewood, but somehow it didn’t respond. So radio chip was taken from computer radio tuner (TEA5757H) which can be easily controlled via 3 wires(DATA, Clock, Write Enable). Additionally mono/stereo selection input is available. To give more control power there was an advanced car audio signal processor TDA7407D used. Audio processor also can be controlled digitally via I2C interface. Temperature reading was implemented with DALLAS DS1820 sensor. As datasheet says, there can be up to 8 temperature sensors connected to one wire, but only tow were used in this project. Program piece of reading temperature sensors was adapted from http://frank.bol.ucla.edu/2313Temper8.htm.
Radio, alarm clock and thermometer – all in one system - [Link]
There are many time servers around the world that provide reliable time by using NTP (Network Time protocol). Everyone can connect to these serves and receive exact time via this simple protocol. Read more about how does it work in http://www.pool.ntp.org/.
Guido Socher from tuxgraphics.org has built nice simple NTP client that can request for time packets from server and display this data on LCD.
He used one of his AVR ethernet boards where simple server application allows easily configure clock settings like NTP server address, time offset, Clock address and more. The web server has also a second page where current time is displayed – the same as on LCD. Author provides ideas on how to build clock, ad even provides source code, but if you just want to have this clock on your table really fast on then buy a kit from http://shop.tuxgraphics.org/and support Guido for his nice ideas.
AVR Network Time Protocol Clock - [Link]
Strangeness of this clock is in its expression of numbers, which is realized using seven Leds. Leds are located inside a pipe, one above another and if we move Leds enough fast left or right, we have a space where we can write numbers, characters or anything else. All these are possible only if we turn on specific Leds at precision timing. Moving LEDs left or right is achieved using a steel plate, so we have to tense the pipe in one direction (left or right) and let pipe to vibrate by itself.
Unusual clock with AT89C2051 - [Link]
This is a digital clock and temperature display which is alernate display between time and temperature.
- Display time 24-hour format. 00:00 – 23:00
- Use DS1307 RTC with 3V betterry back-up.
- 1 channel temperature sensor(DS1820)
- measures temperatures from -55 to + 125 degree Celsius.
- Temperature accuracy 0.5 ‘C
- software compiled with CCS C compiler V 3.222
Digital Clock and Temperature - [Link]