Tag Archives: pic18

Thermometer with PIC Microcontroller

In the last tutorial we learn about the multiplexing technique used with seven segment displays. We learnt how it saves i/o line by using persistence of vision. Only one digit is lit at a time, but to a human eye it is too fast to catch, so we see all four digit lit the same time. In this tutorial we will make a practical use of multiplexed seven segment displays. We will use them to show current room temperature using a LM35 temperature sensor. Before reading further make sure you know the following concepts Multiplexing Seven Segment Display with PIC Micro. Using ADC of PIC Micro. Interfacing LM35 temperature sensor with PIC Micro. Schematic for PIC Thermometer Please note that this schematic is slightly different from our previous schematic on multiplexed seven segment display. The display select i/o pins were RA0,RA1,RA2,RA3 on that schematic. But in this schematic the display lines are RA1,RA2,RA3,RA4 this is because RA0 is used as analog input channel for LM35′s output. PIC Thermometer using LM35   Multiplexed Seven Segment wiring We use our PIC Development Board for making the above demo project. The PIC Development Board has all the core circuitry to sustain the MCU while the project specific part is developed on the expansion board. Multiplexed Seven Segment Display Setup   Multiplexed Seven Segment […]

Introduction to PIC Interrupts and their Handling in C

Interrupts are common features in almost all processor family, be it old 8051, AVR, PIC, ARM or the x86 used in desktops. So their in depth and clear knowledge is required for successful system software engineers. This guide will explain the interrupt system in general and their application using PIC18 architecture. We will also learn about handling of interrupts in HI-TECH C for PIC18. What are Interrupts? Interrupts, as the name suggests interrupts the normal execution and Requests and urgent attention of CPU. Interrupts are situations that the CPU can’t predict when they will happen, they can happen any time, so the CPU does not wait for them. So the CPU keeps on doing its normal job unless and interrupt occurs. For example when the USART (Serial Communication Hardware) will receive data is unknown, it can receive data any time. So the CPU keeps on doing its normal job, which may be for example read temperature using LM35 sensor and display on LCD. The CPU keeps on doing the "normal" job, but as soon as the USART receive data it informs the CPU using an interrupt. The CPU save its current state (so that it can resume), and jumps to the ISR (interrupt service routine) immediately. Where we can process the command or put it in a FIFO queue (to […]

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Using Analog to Digital Converter (ADC) – PIC Microcontroller Tutorial

Many electrical signals around us are Analog in nature. That means a quantity varies directly with some other quantity. The first quantity is mostly voltage while that second quantity can be anything like temperature, pressure, light, force or acceleration. For example in LM35 temperature sensor the output voltage varies according to the temperature, so if we could measure voltage, we can measure temperature. But most of our computer (or Microcontrollers) are digital in nature. They can only differentiate between HIGH or LOW level on input pins. For example if input is more than 2.5v it will be read as 1 and if it is below 2.5 then it will be read as 0 (in case of 5v systems). So we cannot measure voltage directly from MCUs. To solve this problem most modern MCUs have an ADC unit. ADC stands for analog to digital converter. It will convert a voltage to a number so that it can be processed by a digital systems like MCU. This enables us to easily interface all sort of analog devices with MCUs. Some really helpful example of analog devices are Light Sensors. Temperature Sensors. Accelerometers. Touch Screens. Microphone for Audio Recording. And possibly many more. In this tutorials we will learn to use the internal ADC of PIC18 devices (Example is for PIC18F4520 which is […]

Making “The LCD Expansion Board” for PIC18F4520

In this tutorial I you show you how to make a very useful expansion board for our PIC development board. It will be a Do It Your self (DIY) LCD Expansion board. The expansion board can be plugged into the PIC development board to add 16×2 Alphanumeric LCD Support to it. Since LCDs are required in many projects and experiments it will be a very helpful board. I recommend you to read the LCD Interfacing Tutorial before you proceed. It will give you an Idea how LCD is connected to PIC Microcontrollers. So lets start! Schematic for LCD Expansion Board. Fig.: LCD Module Interface with PIC Microcontroller. The board is very easy to make as the MCU core unit is already done for you. So you need to just care about the LCD part. It consists of the 16×2 LCD Module and A variable resistor (10K) only! Optionally you can add a 47ohm series resistor with the LED backlight of the LCD Module, to enable the backlight. The variable resistor is used to adjust the contrast of the module. If NO text is displayed adjust this pot. All I/O ports and power supply is available at the top of expansion board. Fig.: A blank expansion. As you can see the top row in the board lists all I/O port of […]

Introduction to PIC18′s Timers – PIC Microcontroller Tutorial

Timers are common features of most microcontroller. In simplified terms a timer is just a register whose value keeps increasing (or decreasing) by a constant rate without the help of the CPU. The CPU can read or write this register any time. It reads it find out how much time has elapsed. The Timer register can have the following bit length 8 bit timers – These can count between between 0-255 16 bit timers – These can count between 0-65536 32 bit timers – These can count between 0-4294967296 A timer has a clock source, for example of the clock source of 10KHz is input to a timer then one increment will take 100uS (micro second). This clock source can be obtained from the CPU clock. The CPU clock of popular MCU ranges from 1 MHz to 20Mhz, this can be sometimes too fast. To help us out their is a thing called prescaler in the MCU. The job of prescaler is to divide the CPU clock to obtain a smaller frequency. The PIC Micro that we will use in this example has the following prescaler division factors available. 256 128 64 32 16 8 4 2 1 (Prescaler by-passed) Timers are also called Counters this is because they can be used to count external events. The following example illustrate […]

RS232 Communication using PIC18F4520′s USART – PIC Microcontroller Tutorial

Hello Friends! In this tutorial I will discuss how to practically do a simple communication over RS232 interface. For those who are completely new to this I clarify that the motive is to send and receive data between two device using a standard called RS232. RS232 is serial interface that means that data is transferred BIT by BIT at a time. Since data is transferred BIT by BIT so we need only a single wire two send data and an another one to receive data. One more common wire (called GND) is required between two separate circuit to enable current flow. So a total of three wire are required for communication. RS232 can be used to communicate between a variety of devices. Like your MCU and a GSM module or a PC. In this tutorial we will demonstrate a link between a PIC18F4520 MCU and a standard PC. On PC we will run a terminal program like RealTerm or Hyperterminal. A terminal program is used to send and receive text data. So any text send by the MCU will be visible on Terminal Screen and Any keypress you make on the PC keyboard will be send over RS232 to your MCU. This configuration is the simplest setup to test and understand RS232 communication. When you have enough knowledge you can […]

PIC Development Board – Expansion of Board

The PIC Development board from eXtreme Electronics has the feature of connecting add-on boards, like user interface board or a motor controller board. You can also make your own expansion board. Actually the board has the ability to connect a prototyping area where you can create your project specific circuit while the "basic" environment for PIC resides on the Development board. Fig.: Replaceable Prototyping Area   In this way many project can be created and kept for future use. Each project resides in its own board when you need that simply pair it with development board and the project is up and running! No messy wiring! Preparing a Veroboard for connection Take a general purpose PCB (veroboard) and solder a 40 PIN right angled burg strip connector in one end. Fig.: Replaceable Prototyping Area Now the it is ready to plug into the Development Board. Fig.: Replaceable Prototyping Area   After you connect your prototyping area to the Dev Board all PORTs of PIC MCU and Power Supply becomes available in the veroboard. Here you can connect all sort of components required by your project. It is very easy to remove the prototyping are and replace it with a fresh new one for another project. Thus a single development board can be used for many different projects. The 40 PIN […]

PIC Development Board – Hello World Project

Hello friends, welcome to this exciting tutorial were we will begin our journey with latest PIC18F micros from Microchip Technologies. This tutorial will give you information on what software/hardware you will require and basic steps on how to get, install, configure and use them. After going through this tutorial you will have a complete setup and knowledge to experiment with these powerful chips !           What you will learn ? MPLab as a powerful IDE. HI-TECH C for PIC18 MCUs as a powerful C Compiler. Creating a new HI-TECH C project in MPLab. Write a C Code to blink LED and compile it to get a HEX code. Configure the MCU for proper oscillator selection. Basic Use for PIC development board from eXtreme Electronics Burn the HEX code to MCU using eXtreme Burner PIC from eXtreme Electronics. Use the programmed MCU to actually blink the LED ! So lets get started !!! First get these stuffs Microchip’s MPLab IDE or Integrated development Environment. This is the central tool from where you can access most of other tools, like the C Compiler. This also lets you create and edit program files and projects. Download this from Microchips Web site and Install it in your computer. Download MPLAB IDE Free. HI-TECH C Pro for PIC18 MCUs – This […]

PIC Development Board – Programming

The PIC Development Board can be easily programmed INCircuit by using our eXtreme Burner – PIC, a PIC Programmer with USB Connectivity. The firmware of a Microcontroller is normally stored in HEX files. This HEX file is generated by an assembler or a Compiler. In this section we will show you how you can transfer a HEX file from your PC to the Microcontroller. NOTE: It is assumed that eXtreme Burner – PIC (hardware) is installed as described in its documentation. It is assumed that eXtreme Burner – PIC (software) is installed as described in its documentation. Connect the PIC development board with the programmer using a six pin female to female cable as shown below. Power on both development board and the burner. Fig. Six pin female to female cable for ICSP.   Fig. 6 PIN ICSP of Development Board.   Fig. 6 PIN ICSP of eXtreme Burner – PIC. Launch eXtreme Burner – PIC from Windows Desktop or Start Menu. Fig.: eXtreme Burner – PIC, Main Screen.   The software is easy to use. First you need to load the HEX file which you want to burn to the MCU. So select Open from File Menu or From the Toolbar. Then select the hex file. Now the HEX file will be loaded and the contents (FLASH,EEPROM,Chip Settings) will […]

Hello World Project With PIC Microcontroller – Part II

Hello Friends, Welcome back. In the last tutorial we started working with MPLab and HI-TECH C Compiler and written our first C program to blink LED. After compiling the program we got the HEX file. Now, in this tutorial we will see how to transfer(burn) the hex file to our Microcontroller chip and then power it up to actually blink the LED. We will use eXtreme Burner – PIC , which is a easy to use GUI programmer for PIC18 MCUs. The burner supports USB connectivity with PC so it is very easy to install and use. Launch eXtreme Burner – PIC from Windows Desktop or Start Menu.   Fig.: eXtreme Burner – PIC, Main Screen.   The software is easy to use. First you need to load the HEX file which was generated by MPLAB+HI-TECH C in previous tutorial. So select Open from File Menu or From the Toolbar. Then select the hex file. Now the HEX file will be loaded and the contents (FLASH,EEPROM,Chip Settings) will be available. Now connect the programmer with your PC by using standard USB Cable the programmer will be automatically detected by software (provided drivers are installed previously) . Apply power to programmer using a 12v DC adaptor. Place a PIC18F4550 chip in the ZIF socket and lock it.   Fig.: eXtreme Burner […]

Hello World Project With PIC Microcontroller – Part I

Hello friends, welcome to this exciting tutorial were we will begin our journey with latest PIC18F micros from Microchip Technologies. This tutorial will give you information on what software/hardware you will require and basic steps on how to get, install, configure and use them. After going through this tutorial you will have a complete setup and knowledge to experiment with these powerful chips !         What you will learn ? MPLab as a powerful IDE. HI-TECH C for PIC18 MCUs as a powerful C Compiler. Creating a new HI-TECH C project in MPLab. Write a C Code to blink LED and compile it to get a HEX code. Configure the MCU for proper oscillator selection. Burn the HEX code to MCU using eXtreme Burner PIC from eXtreme Electronics. Use the programmed MCU to actually blink the LED ! So lets get started !!! First get these stuffs Microchip’s MPLab IDE or Integrated development Environment. This is the central tool from where you can access most of other tools, like the C Compiler. This also lets you create and edit program files and projects. Download this from Microchips Web site and Install it in your computer. Download MPLAB IDE Free. HI-TECH C Pro for PIC18 MCUs – This is will compile the high level human readable programs (in […]