Experiments with PIC16F628A

I recently made a second version of my old 18-pin PIC development board with much more peripheral chips.This board is best suitable for doing experiments with enhanced mid-range PIC microcontrollers, such as PIC16F1827 and PIC16F1847. The board has I/O port expander, external EEPROM, temperature sensor, Quad OpAmp, digital potentiometer chips, and many more features.

MikroC has two sets of built-in library functions for UART communications: Software UART and Hardware UART . Since PIC16F628A has a built-in hardware USART module, we are going to use the Hardware UART library. Some PICs don't have hardware USART, such as PIC16F84A. In such cases, any digital I/O pins of PIC can be used for Asynchronous Serial Data Transfer using mikroC Software UART libraries. Experimental Setup The UART Rx and Tx pins in PIC16F628A are multiplexed with RB1 and RB2 pins. In this experiment, we are just sending some character data from PIC to a PC as demonstration of the technique. On PC, the HyperTerminal program should be running to receive data from the PIC16F628A. Since our PIC board does not have a TTL to RS232 voltage level shifter, we are going to construct it on a breadboard. Here is my Level Shifter Circuit:

This is an extension of Experiment No. 8 ( Click Here ). The PWM output is here connected to power a DC motor through a NPN driving transistor. The motor driving circuit is built in a breadboard, as shown below. The circuit is pretty straight forward, the PWM output from PIC pin drives the BC547 transistor ON and OFF, and the current to drive the motor is provided by the collector current in the transistor. The diode is for back EMF protection. I am using a small 6V DC motor from an old cassette player. For motors that require more current to drive, a darlington transistor pair or high power transistor is recommended.  

Background Many microcontroller applications like generating periodic signals, measuring time interval, keeping date and time, use time as their variable. Therefore, microcontrollers need to have some internal resources to accurately measure time. The PIC16F628A has 3 timer modules which are known as Timer0 , Timer1 , and Timer2 . The basic unit of a timer is a free-run 8-bit or 16-bit incrementing synchronous counter which can be programmed to count internal or external pulses. The count number stored by each counter can be read or modified by accessing the special function register associated with that timer. Some of the bits in these registers are also the indicators of timer overflow, which, therefore, can generate interrupt request to the microcontroller. The use of timer modules to keep record of time elapsed allows the microcontroller to carry on with its other operations like controlling outputs, reading inputs, etc. Timers can also have another asynchronour counter, known...

An EEPROM (Electrically-Erasable Programmable ROM) data memory is one of the important features of flash-based PIC microcontrollers. It is called non-volatile to indicate that it retains the data even when the power is down. Practically speaking, if you want to design a digital lock system, then the password to unlock the system can be saved into the EEPROM, so that when the power is down, the password will still be saved. And other good thing is that the data can be easily modified or overwritten with software control. In this experiment, I am going to show you how to read and write in to the internal EEPROM memory of PIC16F628A using mikroC EEPROM library functions. Here is what we are going to do: We will write 0s to 10 EEPROM locations. We will read them first, then write 0-9 to these locations, and turn the power off. We will turn the power on, and read the data in those locations and see. I have created a simple menu on LCD with Read, Write and Delete functions. Experimental...

In this experiment, we are going to build a digital temperature meter using DS1820 connected to our PIC16F628A development board. The temperature value will be displayed on the LCD display. I have modified the sample program that comes with the compiler according to our PIC board requirements. Also I have elaborated comments in the program so that every step will be more clear to the readers. Experimental Setup: The experimental setup is very straight-forward. Place DS1820 device on the three-pin female header that we recently added to our board. And also connect the data pin of DS1820 to RB.0 pin of PIC16F628A using a jumper wire.  

The 1-Wire is a registered trademark of Dallas Semiconductor Corp (now Maxim) for a serial communication protocol using a single data line and a ground reference. A 1-Wire Master (a microcontroller) initiates and controls the communication with one or more 1-Wire Slave devices (usually sensors). Each 1-Wire slave device has a unique, factory-programmed , 64-bit identifier, which serves as device address on the 1-Wire bus. This globally unique address is composed of eight bytes divided into three main sections. Starting with the LSB, the first byte stores the 8-bit family codes that identify the device type. The next six bytes store a customizable 48-bit individual address. The last byte, the most significant byte (MSB), contains a cyclic redundancy check (CRC) with a value based on the data contained in the first seven bytes. This allows the master to determine if an address was read without error. With a 248 serial number pool, conflicting or duplicate node addresses on the net are ne...

mikroC PRO for PIC 2009 is a C compiler for PIC microcontrollers. We are going to use the demo version of this for our PIC board. Download Here mikroC PRO for PIC 2009 Manual Install the Compiler and read the manual before doing experiments.

The development board we are going to make for our experimental microcontroller PIC16F628A will look like this. Here are the features it is going to have: Access to all I/O pins through female header pins 4 Push Buttons for Input 4 LEDs for Output An LCD Interface Port A 4-digit Seven-Segment Display Interface LCD Backlight Switch and Contrast Adjustment ICSP Programming (Very Important)