Archives for May, 2013
LCDs are alphanumeric (or graphical) displays, which are frequently used in microcontroller based applications which require some information to be displayed to the user. There are many devices in the market which come in different shapes and sizes. Some LCDs have 40 or more character lengths with the capability to display several lines. Some other LCD displays can be programmed to display graphic images. Some modules offer color displays, while some others incorporate back lighting so that they can be viewed in dimly lit conditions. In this tutorial we will learn how to connect an LCD to any PORT of a microcontroller, display characters and send commands to LCD using lcd library with MPLAB Code Configurator and PIC18F Peripheral Libraries.
Analog to Digital converters allow analog continuous voltages to be converted into a discreet digital numbers inside the PIC as the PIC can only process digital numbers. This can enable a PIC to be connected to analog sensors such as temperature sensors, pressure sensors, humidity sensors, optical sensors, and power sensors. Any sensor which can generate a voltage between 0V and a maximum 5V can be used. If the output voltage is higher than 5V, a method to step it down should be used such as a voltage divider with resistors.
Temperature sensors are very important in many projects especially in temperature logging devices and alarms. In this article we are going to design a digital thermometer using MPLAB XC8 compiler. This digital thermometer is built around the LM35 which is a precision integrated-circuit temperature sensor whose output voltage is linearly proportional to the Celsius (Centigrade) temperature. Its output changes by 10 mV per °C so there is no need for calibration. It can measure a wide range of temperature from −55 to +150°C
RS232 serial communication is one of the oldest communication where data is sent or received one bit at a time. This protocol can easily be used to communicate between a PC and various devices supporting this type of protocol like PIC microcontrollers, GPS, GSM modem etc. While other interfaces like Ethernet, FireWire, and USB all send data as a serial stream, the term "serial port" usually identifies hardware more or less compliant to the RS-232 standard, intended to interface with a modem or with a similar communication device. The Universal Asynchronous Receiver/Transmitter (UART) controller is the key component of the serial communications between a device and a PC or between devices. UART is also a common integrated feature in most microcontrollers today which is useful for communicating serial data (text, numbers, etc.) to your PC. In this article we're going to learn how to use the RS232 communication with MPLAB XC8 Compiler using the PIC18F Peripheral Library and MPLAB Code Configurator.
The I²C or Inter-Integrated Circuit is a serial communication and allows multiple devices to communicate with a micocontroller(s) over only two wires. The devices don't have to be identical as long as they support I²C protocol. In our illustration, the first device with address 1 is a digital temperature sensor, the second one is a real time clock and the third one is a serial LCD display and the bus could carry on even more devices. Communication takes place from the master (PIC) to the individual selected slave only as shown in this illustration. Configuration with PIC18F Peripheral Libraries and MPLAB Code Configurator are discussed in this article