AVR based Ethernet development board

AVRnet board is based on AVR Atmega32 microcontroller and ENC28J60 Ethernet controller. Board information can be viewed on LCD with menu navigation buttons.   AVRnet board can be used for various web based controls and data acquisition like temperature sensor reading and logging directly on web page. Current firmware is capable to communicate by using IP, TCP, ICMP, ARP, HTTP protocols. Source code is written under WinAVR compiler tool-set. To start working you will also need to install PHP script in you Apache web server to start reading sensor information via web interface. Continue reading

Three channel fan speed controller for PC

Jos van Eijndhoven have constructed simple but effective PC fan speed controller. He used PIC 16F676 microcontroller to read temperature sensors and provide PWM for three independent channels. Potentiometers control fan start temperature for each fan.     The controller is programmed linearly to increase fan speed when temperature increases and decrease fan speed slowly even if temperature drops fast, in order to avoid instability in control. In Schematic he used switching power MOSFETs BUZ72 to control speed of fans with PWM and LM60 temperature controllers. Also there are ability to connect several fans in parallel to one channel if needed. Code is written in C and compiled to hex with CC5x compiler. Continue reading

Stand alone AVR butterfly datalogger

Nick Lott have been working on datalogger based in AVR butterfly kit. Data-logger is used to monitor environment parameters like temperature, light, voltage, and values from other sensors connected to other inputs: ADC, timer counter. Author wanted to make this project more universal that it could be used in variety projects like weather station, motion-recording with accelerometers, etc.   Datalogger can be configured wia RS232 interface with specially developed queries. With RS232 and joystick you can adjust various logging parameters like logging time intervals and so on. Data is logged to flash memory which contents may be viewed later for instance as graphics. Good ting that project software is open source what allows you to use and change code for you needs. Continue reading

Automated self recording witness camera

This automated witness camera was built by Alberto Ricci Bitti and have won the Grand Price at Atmel’s AVR 2006 Design Contest. The goal was to build inexpensive easy of use automatic camera which may fit bay the door taking snapshots of persons entering, or using inside vehicle. There are meny areas it can be used.   Design is based on Atmega32 Atmel AVR microcontroller where serial JPEG camera is attached. Movement detection is done by PIR sensor and all information is recorded to SD memory card by using standard file system(FAT16 or FAT32). So all pictures can be easily transferred to PC with no special software. Pictures are taken at 640×480 pixels resolution at every 3.5 – 4 seconds. You can select several recording modes including: PIR activated, timer,… Continue reading

Radio spectrum FFT on Atmega8

This experimental project developed by ChaN. He managed to analyze Radiosignal spectrum and calculate its FFT which is displayed on graphical LCD. When analysing RF frequencies there are some problems with speed. Even when analysing 1MHz radio signal there is over 4000 samples needed for correct ADC.   To solve this problem he managed to shift carrier frequency to lover by using generic method: Frequency conversion, which operates with signals as complex, where operations with negative frequencies are available. So if signal is 100MHz with span ±1MHz, then frequency is shifted to 0MHz±1MHz. This way by Nyquist they there is enough to sample signal at 2MHz. In circuit diagram (PCB (top) and PCB (bottom) )there is seen how this conversion is performed with couple mixer circuits SA612A and reference frequency… Continue reading