This AVR DDS generator can generate signals from 1Hz up to 65535Hz. Thanks to well known DDS algorithm frequency limits can be much higher, but signal resolution drops in higher frequencies. Current range is enough for most of audio signal equipment testing. DDS algorithm is written in software where Atmega8 runs at maximum 16MHz. There are several signal waveforms available: sine, square, sawtooth, triangle and reverse sawtooth and pseudo-random noise. Signals are stored in lookup tables as DDS algorithm requires. Signal output is organized via simple R-2R ladder DAC. LCD signal goes through shift register, this way only 3 MCU pins are used, while other serves for other purposes – buttons, other outputs. Project is well documented PCB and source files included. Author states that he will build another … Continue reading
This device so called Station Master is small key ring sized device which tracks movement in the train. As train goes, device vibrates, but when train stops, it generates alarm after predefined number of stops. So you don’t miss your station. Device is based on Atiny13 microcontroller and MMA7260 3 axis accelerometer from Freescale. Alarm is generated by cell phone vibro motor. Project files include schematic and assembly program which is very compact due to smart program optimisation – especially filter part, where movement signal is detected from noise pattern.
This is simple fun PIC project which may fir Christmas decoration. Circuit is simple – 8×8 LEDs are connected to PIC19F84 via 74HC374 buffer sharing same microcontroller port. All you have to do is to burn firmware to se demos, or you can program your own patterns by modifying assembler program. And of course be sure to align LEDs perfectly or use 8×8 LED matrix.
If you are looking for ready AT89 microcontroller projects this is a place to start. Ajay have gathered more than 10 of them. Programs of the projects are written in pure assembly language. Each project have circuit diagram included. Projects include: Auto Control of three phase Induction motor, Automatic College Bell, Automatic plant Irrigation, Automatic Room light Controller with Visitor Counter, Biomedical Monitoring System, Device Controlling through PC, Digital Visitor Counter, DS1820 Based Temperature Controller, Electronic Voting Machine, Fire Fighting Robot and even more older ones. Binu have more cool related information that may be interesting to read.
Didik Rostyono developed nice converter from battery povered 12V DC power supply to 110V and 50Hz wave. To acchieve this he used microcontroller 89S2051, MOSFET switching circuit and transformer. Output signal then is filtered where higher harmonics of signal are filtered and signal appears to be sinusoidal. It is hard to say what loads this circuit is cappable to drive, but this design [perfectly suits for learning purposes.