Mains AC Frequency Monitor using PIC Microchip

This project reads the AC line frequency and displays on a LCD. The 120V AC is first converted to 12V AC using a step-down transformer. With the help of a BJT, the output Sine wave is further converted to 5V square pulses which is fed to TOCKI pin of PIC16F628A. The Timer0 module is used as an 8-bit counter. The counter counts the number of pulses arrived at TOCKI port in 1 sec, which, in fact, is frequency of manis AC, and displays it on a LCD.

PIC16F886 Temperature and Humidity Meter

SHT11 is a digital humidity and temperature sensor on one chip. This project describes the interface between PIC16F886 microchip and SHT11 sensor and displays the measurements on a LCD display.
In order to get temperature or humidity data, SHT11 needs

• Connection reset sequence (consists of at least 9 pulse while data is high).
• Transmission start sequence (consists of lowering data while clock is high follow by lowering and highering clock then release data to high).
• Command byte (consists of 000 and 5bit command code)
• wait untill measurement compleated.
• get 2 bytes data
• get CRC byte if need.

Source: http://www.pic_examples.byethost3.com/SHTP010.jpg