Thursday, September 30, 2010

Digital Temperature Meter using PIC16F688

A digital temperature meter based on PIC16F688 microchip and DS1820 temperature sensor that displays temperature on Celsius and Fahrenheit scales.

Very cool project, firmware written in mikroC compiler.


40x7 Running Message Display using PIC Microcontroller

LED matrix message displays are really cool. Here is one based on PIC microcontroller that displays time, calendar, temperatures, and, text messages. It can store for up to 10 messages, each 250 characters long, and supports both static and running messages. Message selection can be done through an IR remote control. The brain of this device is a PIC18F252 microcontroller and uses 16-bit serial-in-parallel-out shift registers to drive the LED columns. It operates with 12-24 V DC power supply.


Monday, September 27, 2010

Serial LCD Driver using 74HC595 Shift Register

HD44780 based character LCD displays are very popular among hobbyists. They are easy to interface with microcontrollers and most of the present day high-level compilers have in-built routines for them. However, the bad part is at least 6 I/O pins of microcontroller are required to use them in your project. Therefore, they are not applicable for 8-pin devices like PIC12F series microchips. The aim of this project is to allow LCD interfacing to such devices using 3-wires. I am going to demonstrate this with PIC12F683 microcontroller. The character data or command from the microcontroller will be transferred serially to an 8-bit serial-in parallel-out shift register (74HC595), and the parallel output will be fed to the LCD driver pins.

Saturday, September 25, 2010

Frequency Counter Using PIC12F683

The Timer1 module inside PIC12F683 is a 16-bit timer/counter. If used as an asynchronous counter, this module can be used for counting the frequency of an external clock source applied to its GP5/T1CKI port. The following example is a 0-65535 Hz frequency counter using Timer1 module of PIC12F683. The Timer1 module is reset first and then turned ON for 1 sec to count the clock pulses arrived at its T1CKI port during that period. The number of pulses arrived in  second is frequency itself. The measured frequency value is sent to PC through serial port and displayed on a hyperterminal receiver window. If the external clock frequency is over 65535 Hz, Timer1 overflows and an interrupt is generated. In case of the overflow, "Frequency out of range " message is displayed on the window. A 555 Timer IC running as an astable multivibrator is used as the external clock source.

Monday, September 20, 2010

Gas Sensor Using PIC16F84A

Here's a gas sensor circuit based on PIC16F84A and GH-312 sensor. GH-312 is able to sense gases like smoke, liquefied gas, butane and propane, Methane, alcohol, hydrogen, etc. Once it senses any of these gases, it triggers the microcontroller, which in turn switches on a buzzer and flash a LED.

Monday, September 13, 2010

PIC16F628A Mains Frequency Counter

This project reads the AC line frequency and displays on a LCD. The 120V AC is first converted to 12V AC using a step-down transformer. With the help of a BJT, the output Sine wave is further converted to 5V square pulses which is fed to TOCKI pin of PIC16F628A. The Timer0 module is used as an 8-bit counter. The counter counts the number of pulses arrived at TOCKI port in 1 sec, which, in fact, is frequency of manis AC, and displays it on a LCD.

Read rest of the project.

Monday, September 6, 2010

Capacitance Meter: PIC16F88 + mikroC

If you don't have a capacitance measurement on your multimeter, here's one that you can make by yourself. This capacitance meter is based on capacitor charging time. PIC16F88 is used to measure the voltage rise across the capacitor and finds the time required to get the known voltage across it. Then it does some math and finds the capacitance value.

The firmware is written in mikroC. Read rest of the project.

Friday, September 3, 2010

Serial ISP Programmer for ATMEL AT89SXX

What is the first thing that you need when you first step in to the world of microcontrollers? Yes, it is a programmer. ATMEL's AT89S series microcontrollers are popular among hobbyists and designers. This projects describes about a simple serial programmer for AT89SXX microcontrollers.


 The programming software that is available for free provides the following features:

  # Device Supported - AT89S51, AT89S52, AT89S8252, AT89S8253.
  # Read and write  Intel Hex files.
  # Chip Erase.
  # Verify.
  # Lock.
  # Read Device Signature.
  # Advanced Device Specific Functions.

Wednesday, September 1, 2010

PIC Microchip Data Logger

This projects uses a single chip, PIC12F683 microcontroller, for temperature logging. A DS1820 sensor sends temperature value in digital format to PIC12F683 and it stores the value in to its internal EEPROM. The sampling interval for log can be selected from 1 sec, 1min, and 10 min using three tact switches.

The recorded temperature measurements can be downloaded to a PC through a serial interface. Read rest of the project.