Experiments with PIC16F628A

This is a Christmas decoration project using LEDs and PIC microcontroller. The red color LEDs are used to construct a Christmas greeting and the letters in the message are individually controlled through the microcontroller's I/O pins.

This breadboard module is for PIC16F628A microcontroller and it provides access to the I/O ports and the power supply pins through male headers that can be easily inserted into a breadboard. This board will make protyping easier as the external oscillator, reset, and ICSP circuits are already implemented in the module. The layout of the module is shown below. You can construct this board on a general purpose prototyping circuit board.

If your digital multimeter does not have features for testing diodes and transistors, hold on, here's a project that describes how you can construct one by yourself. This project is based on a PIC16F688 microcontroller and uses the simple concept of unidirectional conduction of PN juction to find if the diode or transistor is good or bad. The test results are displayed on a character LCD. It also shows the type of the transistor (NPN or PNP) as well as which of the PN junctions are open or short in a faulty transistor.   Source: http://embedded-lab.com/blog/

Introduction Tachometer is a device that gives you the information about the rotational speed of any shaft or disc. It usually measures the speed in revolutions per minute (RPM). Today we are going to make a simple tachometer that could measure the rotation speed of a disk without making any physical contact (that's why it is contact less) with the rotating object. The range of this tachometer is 0 - 9999 RPM and displays the RPM on a multiplexed 4-digit seven-segment display. Of course, we are going to do this project on our usual PIC16F628A development board. Infrared sensor Contact-less measurement of RPM will be achieved through an IR sensor. An IR diode will send a beam of infrared towards the rotating disc, and any reflected pulse will be received by a photo diode. The resistance of a photo diode drops drastically when exposed to infrared. An infrared is reflected by a white surface and absorbed by the dark ones. The test disc for this project is shown below. You can see ...

Actually this is the another version of my older DVM project that was based on PIC12F683. The older version displays the measured voltage on a LCD that is driven serially by PIC12F683 using 3 I/O pins. The new one uses PIC16F688 microcontroller that doesn't require the serial driver as it has got enough pins to drive a LCD directly in 4-bit mode. The theory and math is just the same. You can read my PIC12F683 version of this project here . Circuit Diagram Circuit on breadboard

This project won the grand prize of 2008 Green Gadgets Design competition. It measures the power consumption of an electrical gadget with high accuracy. The project uses PIC16F877A microcontroller to compute the power and shows the output on a 4-digit multiplexed seven segment display. The power consumed by an electrical appliance is simply the product of voltage across the appliance and the current drawn by it. Voltage measurement is pretty straight forward. Using a resistor divider network, 120 V can be converted down to below 5 V, and can be read through ADC port. However, PIC cannot measure the current directly, it must be converted to voltage first. This is done by a low shunt resistance. This voltage drop across the shunt resistance is too small and requires a precision instrumentation amplifier to boost it to appropriate level.

This is a digital voltmeter project based on PIC12F683 microcontroller. It measures and displays input voltage from 0 to 20V with high accuracy. You cannot feed 20V directly to PIC port, so a simple resistor divider network is used for this purpose. A 5.1V zener diode is used to prevent any damage to PIC port in case the input voltage goes way above 20V. Since PIC12F683 does not have sufficient pins to drive a LCD, 3-wire serial discussed before is used to display the measured voltage.