Tag Archives: pic16f628a

Yet another LC meter using PIC16F628A

PIC based LC meter

DIY LC meter projects are very popular among hobbyists and students. Here is another LC meter project which is based on PIC16F628A microcontroller. It uses a tank oscillator circuit combining a few external components and PIC’s internal comparator module. The L and C values are computed from the resonant frequency of the LC tank circuit. The project also incorporated auto-calibration by shorting the test leads. The meter uses a standard 2×16 character LCD for display.

PIC based LC meter

PIC based LC meter


Lab 21: Servo motor control

Circuit diagram for servo motor control demonstration

A servo motor is a special geared DC motor equipped with an electronic circuit for controlling the direction of rotation, as well as the position, of the motor shaft. Because servo motors allows precise angular positioning of their output shaft, they are used extensively in robotics and radio-controlled cars, airplanes, and boats to control the motion of their various parts. In this lab session, we will first explore what a servo motor consists of and how it works and then illustrate how to interface it with a PIC microcontroller.

Servo motor control using PIC microcontroller

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Making a digital capacitance meter using microcontroller

RC circuit and comparator inputs

Capacitors are one of the most common passive electrical components that are extensively used in all kinds of electronic circuits. In this project, we will discuss a technique of building a digital capacitance meter using a PIC microcontroller. This project can measure capacitance values from 1 nF to 99 ?F, with a resolution of 1 nF. The technique is based on measuring the time elapsed when a capacitor is charged to a known voltage through a series resistor. The microcontroller used in this project is PIC16F628A.

Capacitance meter

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Measurement of temperature and relative humidity using DHT11 sensor and PIC microcontroller

Circuit connections for PIC16F628A and DHT11 sensor

Measurement and control of temperature and relative humidity finds applications in numerous areas. These days devices are available which have both temperature and humidity sensors with signal conditioning, ADC, calibration and communication interface all built inside them. The use of such smart sensors greatly simplify the design and reduces the overall cost. We discussed in past about Humidity and temperature measurements with Sensirion’s SHT1x/SHT7x sensors. These sensors are capable of measuring both temperature and relative humidity and provide fully calibrated digital outputs. While  SHT1x/SHT7x are very accurate sensors, they are still expensive for hobbyists use. This articles discusses the DHT11 sensor which also provides calibrated digital outputs for temperature and humidity but is relatively lot cheaper than the Sensirion sensors. The DHT11 sensor uses a proprietary 1-wire protocol which we will be exploring here and implementing with the PIC16F628A microcontroller that will receive the temperature and humidity values from the sensor and display them on a 16×2 character LCD.

Interfacing DHT11 sensor with PIC16F628A

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00 to 99 minute timer using PIC16F628A microcontroller

Displaying the left over time on LCD

Last week I was browsing my old backup hard drive and I found a source code for a very simple PIC based digital timer that I made a couple of years ago. The actual hardware of the project isn’t with me anymore. I might have lost it when I moved from my old apartment into my new home. However, I thought this might be a good practice project for beginners and so I am sharing it here. I am not going to build it from scratch again; I will rather demonstrate it using my DIY PIC16F628A breadboard module and I/O board. The complete circuit diagram along with the firmware developed using mikroC Pro for PIC compiler is provided in the article.

0-99 minute timer

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