Combination Lock (PIC16F84):
This is a security system comprise on a combination lock. The code is feed to the system is through the use of keypad. So a 16 switches keypad is interfaced with PIC16f84. 24v lock coil is used as lock. the lock coil is energized through scr MAC224, LM2575-5 is sued in power supply section. optocoupler and ldr are also used in the circuit.
Connecting LED to PIC Micro I/O Pins:
MPLAB uses the listand include directives to incorporate support for specific microcontrollers. TRISB is the port control register for Port B. A sleep instruction puts a PICmicro to sleep until it is reset. The example circuit on the next page shows an active-high LED circuit, just like the one connected to each I/O pin on Port B of the PIC16F84 PICmicro.Resistors R1 and R2, along with switch S1, make up the reset circuit for the microcontroller. Capacitors C1, C2, crystal Y1, and resistor R3 form the clock oscillator circuit that runs the PICmicro.The cathode side of an LED isusually marked with a flat spot on the flange that rings the body of thediode. The cathode wire is also usually shorter that the anode wire of an LED. Figure 3, below, comparesan LED with its schematic symbol.
Connecting PIC12C508 to 93A46 Serial Eprom: The 93c46 is serial EEPROM used to sotre the online variable for backup if the power supply is failed. This is just like 24c01-24c512, 93c46-86, 25c080-640, 7002, 77007/5, sde2506, X2400/44/30 in function. The PIC 12c508 or PIC 12c509 is used in this project.
Controller Provides Multiple Alarm Driver Formats: In the sensitive area where high security is required, a security device is required which can have multuple alaram driver formates and must be using microcontrollers for better functionality.
Digital signal controls sine generator:
The circuit produces an accurate, variable-frequency sine wave for use as a general-purpose reference signal. It includes an eighth-order elliptic, switched-capacitor lowpass filter, IC3, which uses a 100-kHz square-wave clock signal that microcontroller IC2 generates. (Any other convenient square-wave source is also acceptable.) The microcontroller receives its clock signal from a 10-MHz oscillator module. A voltage supervisor, IC1, ensures correct operation in the event of a power failure. IC3 sets the filter's cutoff frequency at one-hundredth the clock frequency.
The eighth-order elliptic filter's sharp roll-off sharply reduces the harmonic amplitudes in a 1-kHz square-wave input, thereby producing a nearly perfect 1-kHz sine wave at its output. Using divider-chain logic or a processor, you can then create a digitally adjustable sine-wave source by adjusting the clock and input frequencies and maintain a ratio of 100-to-1 between them. To prevent clipping at the positive and negative peaks, attenuate the input signal and superimpose it on a dc level of VCC/2. The result for a 5V input is a 2.25V peak-to-peak output. shows the assembly code for the microcontroller this application uses.
; PROGRAM NAME : Switched Capacitor Sinewave generator; FILE NAME : Sw_cap.asm
DEVELOPMENT TIME 5 Grolsch; PROCESSOR : AT90S2323; CLOCK SPEED : 10MHz external XTAL ; DESCRIPTION; This code gives 2 clock outputs, CLK1 and CLK2. CLK1 clocks a switched capacitor filter.; CLK2 = CLK1/100, which is the 3dB point of the filter, thus turning CLK2 into a sinewave; With this, we can develop a digitally programmable sinewave oscillator.
*************** TIMER/COUNTER OVERFLOW INTERRUPT ROUTINE ****************Int_T0: ; arrive here on Interrupt
ldi junk, 0xD6 ; reset clock out TCNT0, junk ; to give overflow after 5us
ldi junk1, 0b00000010 in junk, PORTB ; read in Port B eor junk, junk1 out PORTB, junk ; flip bit 1 (CLK1 output)
inc count reti
DS1820 Arbiter V2.00 Schematic:
the 2.4576 MHz frequency is required for accurate baud rate timing. The frequency is 2 (power 7) x 19200 Hz. A Max232 would be better if you are planning to drive a long RS232 cable. Up to 8 DS1820 devices can be connected to each Port B pin. There are 8 Port B I/O pins, giving the total of 64. Dallas DS18B20, PIC16F84A-20/P ,RTS and CTS are connected together. RXD is used to steal a negative supply.
DS1820 Temperature Sensor Readout Unit:
one wire temperature sensor DS-1820 is used to monitor the temperature from a remote location of maximium destance of 50m. eight ds1820 can be connected to a single signal line. so the number of fires are shorted. 8815346
EZ80 Single Board Computer Schematic (Z80):
Z80 is the first 8 bit microprocessor and it is used here to develope a single board computer. The circuit diagram of single board computer using z80 processor is available on the link above. The components used in this board are Z80 CPU, 2764 EPROM 8k, 6116 RAM 2k, RTC MM58167AN real time clock, AY-3-8912 sound generator, 74ls13, 73ls273, 74ls74, seven segment led display , keypad of 12 buttons.
Galvanic Decoupling of I2C Bus: This webpage for the I2C (Inter-Integrated Circuit) Bus Technical Overview and Frequently Asked Questions. In the early 1980's, NXP Semiconductors developed a simple bi-directional 2-wire bus for efficient inter-IC control. This bus is called the Inter-IC or I2C-bus. At present, NXP's IC range includes more than 150 CMOS and bipolar I2C-bus compatible types for performing communication functions between intelligent control devices (e.g. microcontrollers), general-purpose circuits (e.g. LCD drivers, remote I/O ports, memories) and application-oriented circuits (e.g. digital tuning and signal processing circuits for radio and video systems).General Introduction and protocol includes these History of the I2C Bus,I2C Bus Protocol,
I2C Bus Hardware,Bus Arbitration,Clock Synchronization,Using the Clock Synchronizing Mechanism as a Handshake, Special Addresses and Exceptions, Enhanced I2C (FAST Mode),
High-Speed I2C (HS-Mode),Extended Addressing (10-bit),I2C Bus Events,Start and Stop Conditions,Transmitting a Byte to a Slave Device,Receiving a Byte From a Slave Device,Getting Acknowledge from a Slave Device,Giving Acknowledge to a Slave Device,No Acknowledge Condition,Overview of the Different Versions of the I2C Specification,I2C Driver in Psudocode
Giant Money Counter (PIC16F876):
Complete Design for Giant 8-foot LCD Counter
This is the complete design for a giant 8 foot money counter for student debt. It is still working beautifully to this day, counting up student debt in the main library at Canterbury University of New Zealand.
Download the complete design, including sample PIC code in C (for PIC16F876 or pIC16F877), Visual Basic code, Protel 99 .pcb files, plans and photos. Download (1080KB).
GPS LCD Display Project:
a 4 Bit configuration for the LCD to PIC wiring.the GPS data is comming in on PORT A PIN 1. The LCD data goes out on PORT B PINS 0-3. The LCD's Register Select (Rs) is on PORT A PIN 2 and the LCD's Enable (E) is on PORT A PIN 3. In the original design, I had included a MAX232 level converter to do the TTL to Serial conversion before it came into the PIC. I found a serial routine that did software inversion and allowed me to eliminate the MAX232, so one less part. This is really nice because basically the entire circuit could be layed out on a board the same size as the 4x20 LCD.the NMEA data and formatting it to a point.cleaning up the parsing and display functions.
Graphic LCD Interface:
max235 is used instead of rs232, 24lc128 eeprom, PIC 16f876, power supply is between 4 to 12 volt of data loger, dcmg, lm349.
IC16F876 Datalogger: This data logger uses microcontroller PIC 16f876 , serial I2c EEPROM 24ls128 for storing the values of parameters, and lcd screen 2 line 16 characters. serial communication is completed with rs235 chip. This serial rs232 signal convter donot used any capacitors with it(max235). folllowing is the circuit diagram for data logger using pic microcontroller.
Interfacing DRAM to AT90S8515:
Monster Memory , bunch of Hitatchi M5M44800 DRAM's , a 512k*8 DRAM.It uses a 1024 cycle refresh (each 16 mS), and allows CAS-before-RAS refresh.Atmel 8515, the RAS/CAS sequencing , a prescaler value of fClk/1024 (8 MHz CPU), this gives an interrupt every 16 mS. On each interrupt, a loop is executed 1024 times, each iteration doing a CAS-before-RAS access. The loop takes total about 1.6 mS, to execute.
Interfacing Piezo Elements to a Microcontroller:
RFID-Based Liquid Control (Part 1): Working with Off-the-Shelf Components◊ FPGA Embedded Microcontroller Environment◊ Floating Point for DSP◊ Advanced Encryption Standard: Understanding AES Without Math, ABOVE THE GROUND PLANE Totally Featureless Clock (Part 1): WWVB Simulator◊ FROM THE BENCH Sun Tracker (Part 1): Create a Directional Light Sensor◊ SILICON UPDATE A Winning Hand: Betting on the ARM Cortex M3 Interfacing thePIC16C508:
'508A microcontroller can deliver a maximum of 25mA. LEDs (Light Emitting Diodes) require up to about 25mA for full illumination. 2. Piezo diaphragms require very little current and can be driven directly from an output line. 3. Low-current relays can be driven directly provided they operate at 25mA and 5v. If more than 25mA is required, a driver transistor (also called a buffer transistor or buffer stage) will be needed.The resistor is called the LOAD RESISTOR or simply the LOAD. A piezo diaphragm is essentially very similar to a capacitor (approx22n) as far as the micro is concerned. It requires very little current to operate the device.A piezo diaphragm is a passive device. It does not contain any active components to create the tone.Piezo buzzers, piezo sounders and piezo sirens have active components inside the housing (transistors, choke, etc) to create a very loud sound. These devices operate from a DC supply (6v to 12v).