Digital Segments

This uses the MAX7219 serial input/output common-cathode display driver for interfacing microprocessors to 7-segment numeric LED displays of up to 8 digits. We are using a pair of Vishay four digit clock displays with a common cathode.

• Pin1. SPI In
• Pin2. Supply Voltage
• Pin3. Ground
• Pin4. Clock Signal
• Pin5. Chip Select

Notice the digits are individually selectable. Also the driver handling the refreshing of the display takes a load of work off the processor. You can drive up to 64 individual leds with this controller.

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This simple front panel checker was built to make it easier to quickly check leds and switches without having to deal with trying to keep meter probes on the connections.

• Pin1: Switch ground
• Pin2: 3 volt positive to switch
• Pin3: 3 volt positive to LED
• Pin4: LED ground

Most of the time, a circuit like this is not even needed. However if your building up storage where there are multiply front leds, this is a quick way of sorting wires. A simple tool you shouldn't need until you do.

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The AT30TS75 is a standard I2C temperature sensor that is used in many commercial products to provide alarm warning for fan and system failure warnings.

• User-definable nonvolatile (NV) alarm settings
• Threshold alarms can be configured to trigger Hi/Lo on detection
• Supply range of 3.0 to 5.5v with no external components

Applications include thermostatic controls, industrial systems, consumer products, thermometers, or any thermally sensitive system

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This circuit is the simplest bargraph driver you will ever find in an IC package. There are 3 flavors of this chip: LM3914, LM3915, LM3916. Each chip has a pin for pin compatible package while providing both linear and log comparisons based on your chip of choice.

• Pin1. Supply voltage
• Pin2. Ground
• Pin3. Signal input

This 10 segment led bargraph driver chip is excellent for simple 1 volt peak readings in common applications such as audio meters.

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This project is based around a 18F4410 microcontroller, is a simple LED Flasher that has 10 different led sequences which can be controlled through a standard Sony 12b IR remote control.

• Uses common flash patterns for vehicles such as police and utility.
• Pattern speeds can be adjusted for flash rate timings.
• Each IR Cmd is "acknowledged" by flash of red, then green.

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This project was based on the project at vecoven.com. The source code provided on that site is excellent and there was no reason in the world to modify what had already been done.

• This decodes multiple formats such as NEC, RC5, RC6, and Sony
• Uses the standard LCD display libraries included in MPLab.
• Port B is open for interrupts and further programming
• Port A is open for Digital or Analog monitoring of sensors
• Most overkill way to decide if remote batteries might be dead.

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The countdown is up to 9,999 seconds or equivalent to roughly over 2 1/2 hours of delay time. The code could be modified to use the first two digits as the minutes, while the last two digits could function as the seconds value holder.

The circuit is powered by a 5.0 volt supply. The circuit board allows for additional headers to be connected to the multidirectional PORTA as digital or analog inputs.

• Pin1. Programming Voltage
• Pin2. Supply Voltage
• Pin3. Ground
• Pin4. Program Data Signal
• Pin3. Ground

The Program Data and Program Clock signal lines, are shared with both segment A and segment F of the multiplexed display. The two jumpers under the display must be removed to allow the PIC to be programmed while in the circuit.

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Sample I2C code for working with an AS3935 Lightning Detector to monitor and measure weather events up to a 40km radius of the detector. This modual is from Embedded Adventures and can be setup with either I2C or SPI interface. It comes pre calibrated so that you do not have to calculate the calibration of the unit each time.

• Selectable SPI or I2C interface to microcontroller.
• Detects up to a 40km radius.
• Can sense both cloud to ground and cloud to cloud flashes.
• Disturber rejection algorithm.
• Antenna Tuning algorithm for calibration setup.
• Supports wide supply voltage range of 2.4v to 5.5v.
• Applications include weather stations, sports, global positioning.

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The circuit can be compiled either in mode 0 or mode 1 configurations.

• Mode 0 is setup with separate entrance and exit locations. A single beam break at the entrance will count up, while a single beam break at the exit will count down.
• Mode 1 is setup with a single entrance and exit location. The first beam broke will set the direction of the counter up or down, while the second beam registers the count.

The counter will by default show the current occupancy count on the display device. If you wish to see the total count of people who have passed through the circuit, you can hold the blue button down. You can also reset the count to zero for both the current occupancy and the total number of people passed through the sensors at any time by pressing the black button. The device contains 510 save locations.

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This project uses the C18's built in I2C functions to simplify interfacing to the Maxim real time clock. The Maxim real time clock is a BCD clock and calendar with 56 bytes of NV SRAM. It also provides leap year functions and 12 or 24 hour formats.

The chip provides power sense for power failures and will automatically switch to the backup coin cell battery for time keeping functions.

• Pin1 - GROUND.
• Pin2 - SDA Resistor tied high.
• Pin3 - SCL Resistor tied high.
• Pin4 - SQW 1Hz, 4Khz, 8khz, 32Khz.
• Pin5 - VCC 5v+.

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This single transistor circuit can light an LED as in this example when liquid comes in contact between the two leads. This circuit can run for several days before the battery is dead. This is a great short term solution to monitoring temporary moisture problems.

• 1. Red and black wires to area wihere moisture might occur
• 2. Red led will light when moisture comes into contact with probes

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When interfacing the SD Cards to a PIC controller, you either have to use a 3.3v PIC which sometimes is not convenient, or you can build this 5v to 3.3v adaptor to interface with the SD Card.

This approach simply sets up up a voltage divider with the resistors so that the 5v is closer to 3.3v for the card.

The 3.3v out from the SD card is already high enough to trigger the voltage high on the PIC's input pins.

Also by using the 3.3v regulator on the card interface we can plug it into the breadboard and keep everything else at a 5v source. We could tap the 3.3v output pin to source voltage to other 3.3v interfaces if need be.

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The ShiftBrite controller is a pretty kewl RGB Led modual you can pickup from places like sparkfun. It is a serial interface that takes in 10 bit data values for each of the 3 colored leds. The total command per modual is 32 bit..

• Can be used to control single or series of led lights.
• Provides full RGB color control.
• Can be modified for use with RGB led lighting strips.

The only changes you need to make are in the shiftbrite.c file. You will need to define which pins you want to interface with. Once defined you can call the initialization and the pins will be properly configured for use.

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This circuit is a simple vu meter with optional peak hold detection for line level (1.0v Signal)audio measurements. A 18F4410 microchip pic was used to test the sample code with a 10 segment bargraph display. A LM386 amplifier chip is used to boost the line level signals closer to the 0 to 5 volt input expected by the ADC of the microcontroller.

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This is a simple voltage switching power supply based on the LM2576 chip that capable of delievering a more efficent and stable power source than traditional linear voltage regulator circuits used in many smaller devices.

• It is very stable under various loads and conditions.
• It can accept any adaptors even with reverse polarity on the input.
• Can easily deliver up to a 1 amp load with minimum heat generation.
• Available prepackaged as 3.3v, 5.0v, 12.0v, and Adjustable.

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In the microcontroller circuits you will be wiring up, the ICSP header connection will require a resistor between the MCLR and 5 volt reference pins. Rather than jumping a bulky standard resistor, you can simply solder a 10k surface mount between the pins of the program header.

• Cleaner prototyping on breadboard layout.
• Better strain relief on the programmers cable connections .
• Allows easier swapping of microcontroller packages.