Sensing real world parameters like temperature is always fun. This is why temperature sensing projects keep coming and coming. This is really great as there are tons of different temperature sensors around ant they are different in their connection interface and accuracy. In current project there is a TMP275 digital temperature sensor used that is 0.5 °C accurate and uses Two-Wire interface to connect to microcontroller. It has common range like other semiconductor sensors have – that is from -40°C to 125°C.

The other part is pretty standard solution. There is an ATmega8 microcontroller used that reads sensor data and displays it on 4 digit 7 segment LED indicator. It has a 7805 voltage regulator on board so it can be powered from a standard 9V battery. Project is well documented and commented. I’d say this is pretty nice digital thermometer which does what it supposes to do – it shows ambient temperature.

This project intended to be simple and fully featured game system. It uses 3 AVR microcontrollers that are responsible for different tasks like generating composite video signal, IR receiver decoder, and sound effects.

Game generates simple monochrome image on TV screen and plays monophonic sound. It is also featured with dual axis Memsic 2125 accelerometer that acts as additional control for joystick. Project seems to be still under intense polishing and more info will be published soon. It actually looks very promising game system so keep track of it.

Mbed platform is based on LPC1768 microcontroller which has a great power to perform most signal processing in audio level. Current effect generator is fairly simple as it uses a standard electret microphone that is connected through several stages of OP amps operating as buffer, amplifier and low pass filter (10-15kHz). Then signal enters a microcontroller for some processing. And then signal leaves microcontroller via DAC  to output amps.

Effect platform is doing great job. It can do simple tasks like delay, echoing. For more audio effects there is more complex signal processing needed like FFT and digital filtering where DSP processor would be better choice. But still mbed platform is quite powerful to try more.

When working with digital electronics you may need a simple logic probe to measure logic levels. This is a simple PIC 12F683 microcontroller based logic level tester which is capable of measuring logic levels from TTL (5V) up to PLC’s (24V).

When pointed, probe indicates weather test point has high impedance (yellow LED), weather logic “1” (green LED) or “0” (red LED). It is very simple device everyone can build. Because it is battery operated device, after 3 minutes probe goes to sleep mode until button is pressed again and new measurement is made. Build one, and you won’t need a scope every time to test logic levels.