Experiments with PIC16F628A

Sensirion's SHT series of humidity sensors integrate sensor elements with all the required signal processing circuits on chip, and provide fully calibrated digital outputs for relative humidity and temperature measurements. This tutorial explains how you can interface a SHT1x/7x sensor to a PIC microcontroller to measure ambient temperature and relative humidity. The tutorial described in full detail about the sensors, their specifications and interface, and the implementation of communication protocol using mikroC compiler.

LED dot matrices are very popular means of displaying information as it allows both static and animated text and images. This tutorial describes the basic architecture of a LED dot matrix display and its interfacing with a microcontroller (PIC18F2550) to display static characters and special symbols.

While prototyping your new project, you might want to know how much power your designed circuit will draw from the source voltage. One way to find it is to connect an ammeter in series with the circuit and determine the current drawn from the source. Then, knowing the source voltage you can easily determine the power. But doing this may not be always convenient. This project describes a special power supply unit that has built-in features for measuring the source voltage and current. Therefore, you can monitor both the parameters continuously while experimenting your circuit.

A 4x3 matrix keypad requires 7 I/O pins of microcontroller for interfacing. But you could reduce the required number of connections to two by using a 555 timer IC. If you want to know how, visit Embedded Lab's new post " 2-Wire Keypad Interfacing using 555 Timer ".

Resting heart rate is an very important health parameter that is directly related to the soundness of human cardiovascular system. This project describes a digital method of measuring heart rate through fingertip. The blood volume inside the finger artery fluctuates with heartbeats. This fluctuation can be measured by transmitting an IR light through the finger. A portion of this light is reflected back. The amount of light reflected back depends upon the blood volume. This small change in the reflected light is amplified through proper signal conditioning circuit and converted into a pulse. Later, a PIC16F628A microcontroller is used to count the pulses at the output of the signal conditioner and display the heart rate on seven segment LEDs. The signal conditioning circuit uses two operational amplifiers to build a two-stage active low-pass filter with a gain of about 10000, and a cut-off frequency close to 2.5 Hz.

H-Bridge is a very popular application circuit for dc motor control. It uses BJTs or MOSFETs to switch on the dc motor in clockwise or counterclockwise direction. This tutorial describes the classical H-bridge circuit and how to interface it with a PIC microcontroller to operate a DC motor.