Electronics Guides And Projects: Site Info
This site is setup to share electronics based
project that I have done
in the pass and projects that I am currently working on. Besides being a
directory to the projects, I have included some guides to help people
that are interested in electronic for some simple projects. Hope all the
visitor to the sites will find it helpful. Any comments on the site are
much appreciated.
This site will no longer be updated. Check out the new site at www.bitguides.com for latest updates.
List of recent projects that I have done
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Electromyogram (EMG) Amplifier Electrical potentials are generated by muscle when there is movement. This Signal can be pick up by electrode to form EMG. For my Final Year Project, I did an amplifier and signal conditioning circuit for EMG. Attached below is the schematics for the Amplifier.Disposable surface electrode are used to pick up the signal. The amplitude of the signal pick up is low, so amplification is needed to measure the detected signal. A differential amplifier is needed because of the high CMRR. 2 electrodes are connected in between the region of interest and the ground electrode is connected to a reference point. A driven feedback is implemented in the design to improve the signal quality. 2nd order active low pass ...
Posted Feb 8, 2011, 6:44 PM by Danny Ng -
Solar Battery Charger Few years back, I had been working on a project for solar auto lighting. The light will turn on when the the solar panel voltage drop below a set point indicating that it is dark. The detection is done by using D2 in the schematic. The zener diode value will be adjusted so that the transition between the switch depends on the amount of light the panel receive. Relay K1 is used to switch the load and the battery. If the battery power fall below a set threshold, the relay will cut the supply to the load. Relay K2 is used to control the charging of the circuit. When a Set point is reach the charging will be cut off ...
Posted Feb 8, 2011, 6:39 PM by Danny Ng
Guides on developing on PIC18
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I2C using Master Synchronous Serial Port (MSSP) Module I2C are widely use for to communicate with external peripheral such as port expender, EEPROM, Real Time Clock etc. The Master Synchronous Serial Port (MSSP) module in PIC18 can be used to communicated with I2C peripheral. MSSP module can be configure to work as SPI and I2C. In this example the module will be configured as I2C to communicate with a port expender from Microchip MCP23017. The circuit below is built up on breadboard to test the MSSP function as an I2C module. The DIL switch on Port B is used to control the LED on Port A of the IO expender. INTB from the IC is connected to the INT2 pin of the PIC so that the PORTA output ...
Posted Apr 19, 2011, 10:53 PM by Danny Ng -
Using Timer and Interrupt in C18 There are 4 timers in PIC18 which are timer0 to timer3. Timers are used when precise timing event need to be generated. Timers are usually used in conjunction with interrupt to keep the timing accurate. This guide will show an example of using timer0 to count a timer for every second. The circuit used for this example is the same as the circuit used in the PWM guide.The back light of the LCD will blink on and off every second, while the counter on the LCD will increase until it reaches 199 then reset back to 0. The counting of second is implemented using an interrupt service routine. The guide will be divided in to 2 parts, 1st part ...
Posted Jun 23, 2011, 12:49 AM by Danny Ng -
PWM using C18 The use of pulse width modulation (PWM) is common for the use of controlling power to a particular electrical device. Motor speed control, LED contrast control, power supplies are some of the example usage of PWM. 18 series PIC always come with a CCP module which is capable of generating PWM. The picture below shows an example of using the capture/compare/pwm (CCP) module to control the LED brightness. PWM duty cycle is set accordingly using the value obtain from the potential meter through the ADC with 5v being the brightness and 0v dimmest for the LED.The test circuit below is constructed to test the PWM module of PIC18f2455. LED of the 2x16 LCD is controlled by a ...
Posted Feb 8, 2011, 6:43 PM by Danny Ng -
Analog to digital converter on PIC18 The analog to digital converter (ADC) is a commonly required in most of the projects. Analog voltage measurement can be done using the ADC hardware built in together in a PIC. The picture below show a simple setup for measuring the voltage through the adjustment of the potentiometer. PIC used in this example come with a 10 bit ADC. In the picture the hex value shown is the ADC value acquired from the hardware. After a simple conversion the voltage can be obtain from this value.A simple circuit is constructed to test the ADC. The potentiometer is use to vary the voltage level on the AN0 pin.The next step would be to configure the register on the PIC ...
Posted Feb 8, 2011, 6:41 PM by Danny Ng -
Auto Baud Rate Based on EUSART module Most of the newer PIC come with the EUSART module which have the function for auto baud rate detection. The features allow a person to set the baud rate at runtime by sending the character "U" or 0x55 to the PIC. With ABDEN (auto baud rate enable) bit set and using BRG clock as a reference, each rising edge occurring on the RX pin is taken as a reference to calculate the SPBRG and SPBRGH value. After the Baud rate is set, the RCIF flag will be set. The receive register must be discarded as it doesn't contain meaningful data. The Image (PIC18F2455 datasheet, page 252) below shows the timing diagram for auto baud rate setup.A circuit based ...
Posted Feb 8, 2011, 6:42 PM by Danny Ng
Software
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Timer 0 Calculator and Code generation A simple gadget is developed for the calculation of PIC18 timer 0 setup and period reload register. The gadget below allow the generation of code to allow the usage of timer 1 to interrupt at the time needed. By keying in the needed time period and oscillator frequency the calculator will calculate the best reload value for timer0. The code generated can be used on the C18 compiler. Please report to me if you have discover any bug on this gadget.
Posted Feb 8, 2011, 6:33 PM by Danny Ng -
SPTerm (Serial Port Terminal) SPTerm is a terminal use for communication between PC and a serial device. Newer version of window doesn't come with hyper terminal that allow basic serial communication through com port of a PC. SPTerm is developed to help me in part of my work that would need to check the communication with UART devices on my certain projects. The screenshot below show the main window of SPTermSPTerm will scan the computer for available com port in the PC. Setting for Stop bit, baud rate, parity and Bits can be selected before opening the connection to the port. When the serial port is open any data that is received will be displayed in the ASCII box while the Hex ...
Posted Dec 28, 2011, 5:17 PM by Danny Ng
