Electronics-Lab.com Blog

Learn how to interface PCF8583 Real Time Clock with an AVR microcontroller. Source code is included.

avrprojects.net writes:

The PCF8583 is a clock/calendar circuit based on a 2048-bit static CMOS RAM organized as 256 words by 8 bits. Addresses and data are transferred serially via the two-line bidirectional I2C-bus. The built-in word address register is incremented automatically after each written or read data byte. Address pin A0 is used for programming the hardware address, allowing the connection of two devices to the bus without additional hardware.The built-in 32.768 kHz oscillator circuit and the first 8 bytes of the RAM are used for the clock/calendar and counter functions. The next 8 bytes may be programmed as alarm registers or used as free RAM space. The remaining 240 bytes are free RAM locations.

Real Time Clock PCF8583 - [Link]

The idea of this project was to build DIY autopilot kit that anyone could build and use in their flying models like helicopters. Autopilot uses two dual axis ADXL202 accelerometers to read 3D acceleration, also it reads attitude, engine stats, position, payload stats. All these readings and control is operated by realtime system OS, which reads each sensor at some predefined rate. This is really quite complex system which seems to be stil under development – but it already gives positive results. [via]

Autopilot for autonomous aerial hobbyist vehicles - [Link]

There may be some situations when it is hard to use a tachometer only because it is impossible to read revolutions per minute mechanically. The only way is to read RPM without touching rotating shaft. This great design was constructed by Ibrahim Kamal who used an IR signal to transmit and receive it reflected from reflective stripe fixed to rotating shaft. Device is controlled by AT89S52 microcontroller which counts reflected pulses and displays value on LCD. RPM counting algorithm uses last three times between pulses and this way constantly gives instant RPM value. RPM meter consists of two parts: microcontroller board and IR proximity sensor connected to microcontroller board via simple 4 wire cable. Project files are available for download in a single zip.

Contact-less tachometer counts up to 99kRPM - [Link]

An iButtonTM is a chip housed in a stainless steel enclosure. The electrical interface is reduced to the absolute minimum, i.e., a single data line plus a ground reference. The energy needed for operation is “stolen” from the data line (“parasitic power”). The logical function of the DS1990A is a simple serial number. This globally unique registration number is common to all iButtons. For read operations all devices are satisfied with a 5kOhm pull-up resistor to supply energy and to terminate the 1-Wire bus.

iButton Adapter - [Link]

This simple device, designed by Wichit Sirichote, measures the quality of AC voltage. The device measures 3rd harmonic which is used to find the distortion value comparing to fundamental frequency. Device calculates DFT of signal which is captured via step down isolation transformer and 10-bit ADC. Testing showed that clean sine wave gives less than 0.5% of distortion, while square wave gives about 33%. Project description includes detailed measurement theory outline and practical examples as well. Project is built on test board which was developed for general purposes. Source code is available for download. [via]

PIC18F2550 based harmonic distortion meter - [Link]

RFM12 is a transmitter and receiver module in single board. It can be powered by using 2.2V to 5.4. It makes ideal module for embedded systems. Module communicates via SPI interface. Wigbert Picht and Dirk Milewski have made simple Atmega8 tesboard, where RFM12 module is soldered as SMD element and can be configured with jumpers. There can be any sensors connected to this board like temperature. [via]

Interfacing RFM12 transceiver module - [Link]

ibsimed1 have developed a single I/O-Pin 3×7-Segment Display board. It only needs one microcontroller I/O pin and power source. The board itself is very simple but idea is great – it uses three serial to paralel converters 74HC164 which activates LED segments. As it is said – display board uses only one I/O pin which also serves as CLK source for serial to paralel converters (from 500kHz to 8MHz). [via]

Control 3×7 segment LED display with one MCU pin - [Link]

DiSEqC-Switch is widely used in individual satellite systems to connect up to 16 satellites to one receiver using cascading method. This switch uses other cheap DiSEqC-Switches ver1.0 with four satelite heads each or simply connects directly to satelite heads and this way acts as simple switch. [via]

Connect up to 16 satellites to one receiver with AVR DiSEqC switch - [Link]

Maker Jimmie Rodgers posted this flashlight variation of the Joule Thief to the MAKE Flickr pool. Take a look. [via]

Joule Thief flashlight - [Link]

Chipwich writes -

We built a beeping flashing toothbrush timer like the one on the Philips SoniCare toothbrush for just a few dollars and plenty of experience and fun.

DIY Picaxe toothbrush timer - [Link]