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6 Jul 2015

This project is an automatic pet feeding system using NXP Semiconductors’ PCA8565. The PCA8565 is a CMOS1 real time clock and calendar optimized for low power consumption. A programmable clock output, interrupt output and voltage-low detector are also provided. All address and data are transferred serially via a two-line bidirectional I2C-bus with a maximum bus speed of 400kbps. The built-in word address register is incremented automatically after each written or read data byte. It provides a year, month, day, weekday, hours, minutes and seconds based on a 32.768kHz quartz crystal. It features alarm and timer functions, low current, and extended operating temperature range of -40 degrees Celsius to +125 degrees Celsius. It further contains an 8-bit year register that can hold values from 00 to 99 in BCD format. It also compensates for leap years, thus leap year correction is automatic.

The electronic part of the device is just an alarm clock based on NXP PCA8565. The alarm initiates an interrupt that awakes the microcontroller. The later one sends a signal to the motor to control its forward and reverse mechanism. The dc motor must make a full turn and stop in the initial position to be ready for the next loading. This is achieved by an opto-interrupter OBP625, which provides a feedback to the microcontroller to stop powering the motor. The motor itself is controlled by PWM based on the timer IC in order to slow it down to a practical speed. The current time and the alarm time are displayed by a 4-digit LED display combined from two HDSP-521E 2-digit displays. Time to display is selected by a 3-state slider connected to pins RA0 and RA1 of PIC16F684. In the middle position of this switch both inputs are pulled up (internally). Two buttons at inputs RA4 and RA5 accomplish time setting and alarm setting. The LED display is controlled by SAA1064. The controller and PIC communicate via the I2C interface. The display is turned OFF after 10 seconds upon release of any button. This is achieved by simply turning OFF the controller and display power by a MOSFET IRLML6402 when the voltage on pin RC2 of PIC becomes 5V.

Food and water are two essential elements for keeping pets happy and healthy. But what happens if you have to work all day, can you imagine that starving look when you come home? As a pet owner, you have to find a way that your pet is fed on time. Keep your pet well fed when you’re away using the automatic pet feeder. You never have to worry about rushing home or working late. It ensures that your pets never miss a meal and maintain their regular eating schedule.

Automatic Pet Feeder – [Link]

22 Jun 2015


2 Diodes, 3 resistors and a transistor here’s Silicon Labs’ low cost solution on voltage level translation. [via]

This applications note discusses a low-cost circuit for I2C level translation. This circuit was developed for the Si701x, Si702x, and Si703x humidity sensors but will work in many applications. This circuit provides I2C level translation from a higher voltage supply, such as 5 V, to a lower voltage, supply such as 1.8 or 3.3 V. In addition, the optional emitter follower circuit provides a low-voltage power supply rail from the higher 5 V supply. Note that some devices allow for higher voltage tolerance on I2C inputs. For example, the Si7034 has a 3.3 V tolerant I2C interface, so the level translation is only required for 5 V I2C designs.

App note: Low cost I2C level translator – [Link]

12 Jun 2015


The SmartScope designed by the young Belgian company LabNation is — to our knowledge — the only oscilloscope that works with all popular operating systems: Windows 7/8, Linux, OS X, iOS (jailbroken) and Android 4.0+. So the software can run on a standard PC or laptop, but also on a tablet or smartphone. The control interface is specifically designed to operate with touch-screen or mouse and is equipped with various software decoders (such as I2C and SPI) for decoding digital signals.

The Smart Scope hardware consists of a small metal housing (for good protection) with the front two full BNC connectors for analog inputs, and at the rear a 16-pin header which has 8 digital inputs for the logic analyzer. Four digital outputs and an output for the built-in arbitrary waveform generator (AWG) are available. The sampling frequency of the analog and digital inputs is 100 Msamples/s, the maximum data rate of the AWG is 50 Msamples/s.

LabNation SmartScope: unique multi-platform USB oscilloscope – [Link]

9 Jun 2015



TI’s new bq25890, bq25892, and bq25895 5A chargers with TI’s MaxCharge™ technology charge your mobile device faster while keeping your device cooler. The switch-mode chargers can charge a 1-S Li-Ion cell to 80% capacity in 30 minutes, while traditional devices only reach 30%. The I2C-controlled chargers’ high efficiency and thermal management result in the fastest, safest and coolest charging capability.

Key features and benefits

  • Fast charging to high capacity battery with up to 5A high charging current
  • Optimized for high voltage input: >91% charging efficiency at 3A with 9V input
  • Innovative Input Current Optimizer (ICO) to maximize input power without overloading adapter
  • Resistance compensation from charger output to cell terminal to enhance power delivery to battery
  • Integrated ADC for charging system monitoring

Single-cell 5-A Li-Ion battery charger with MaxCharge™ technology – [Link]

9 Jun 2015

The MMA955xL platform as a sensor hub is an intelligent sensing hub with built-in accelerometer, signal conditioning, and data conversion with 32-bit programmable microcontroller and temperature sensor. In addition, it has a second I2C bus and one external analog input, which can be monitored using the on-chip Analog-to-Digital (ADC). This unique blend transforms Freescale’s MMA955xL into an intelligent, high precision, motion-sensing platform able to manage multiple sensor inputs.

The combination of low power consumption and powerful features means that the MMA955xL platform can effectively operate as a power controller for handheld units such as industrial scanners, Personal Digital Assistant (PDA), and games. The host platform can put itself to sleep with confidence that the MMA955xL device will issue a wake request should any external event require its attention. The MMA955xL device is programmed and configured with the codewarrior development studio for micro-controllers software. This standard integrated design environment enables customers to quickly implement custom algorithms and features to exactly match their application needs. Using the master I2C port, the MMA955xL device can manage secondary sensors, such as pressure sensors, magnetometers, or gyroscopes. This allows sensor initialization, calibration, data compensation, and computation functions to be off-loaded from the system application processor. The MMA955xL device also acts as an intelligent sensing hub and a highly configurable decision engine. Total system power consumption is significantly reduced because the application processor stays powered down until absolutely needed.

This device is optimized for use in portable and mobile consumer products that can make system-level decisions required for practical applications such as gesture recognition, pedometer functionality, tilt compensation and calibration, and activity monitoring. This may be applicable to tablets, digital cameras, smartbooks, laptops, gaming and security system as well as used in medical applications.

Intelligent Motion-Sensing Platform – [Link]

26 May 2015


by MIKE BARELA @ adafruit.com:

Trinket lends itself very well to building clock projects, its small and easy to hide behind a larger display. And clocks don’t need a lot of logic, this example only has maybe 20 lines of code. Adding a digital display via I2C is possible using seven segment or character-based displays (with the library code posted for other projects).

This project interfaces Trinket to the the Adafruit DS1307 real-time clock (RTC) breakout board to form a clock. But in a twist, the display is done using two analog meters. One for hours, one for minutes.

The Trinket can output to a meter without digital to analog converters. Trinket has pulse width modulation (PWM) on three of its pins. The meter uses a moving coil inductance movement, acting to average the indication of current flowing through it. If you have narrow pulses, the average voltage it sees is lower, thus the current is lower for the fixed resistance attached to it. For wide pulses, the meter sees nearly the supply voltage and will stay around the full scale. This circuit varies the pulse width sent to the meters proportional to the hour of the day and the minutes after the hour.

Meter Clock using a DS1307 RTC and Trinket Microcontroller – [Link]

18 May 2015


LAPIS Semiconductor has recently announced the development of a low power microcontroller that has an integrated 8-bit low power MCU core, speech synthesis circuit, highly efficient Class-D speaker amp, non-volatile memory and oscillator circuit on a single chip, making audio playback possible by simply wiring up a speaker.

The ML610Q304 has a typical audio power output of 450 mW operating at 3 V or 1 W at 5 V. The controller includes four 8-bit counters which can be combined to make two 16-bit timers, a three channel 10-bit A/D converter, a two channel SSIO, UART and I2C peripheral interfaces. The memory capacity of the ML610Q304 includes a 96 KB program flash, 2 KB data flash and 1 KB RAM. The dedicated hardware-based audio playback helps reduce CPU loading. Two suggested audio playback formats are 16 kHz 16-bit PCM and 16kHz HQ-ADPCM. The Class-D amp reduces current consumption during audio playback by approx. 40% compared to conventional solutions, making it a good choice for incorporation into mobile battery-powered devices. In recent years a growing number of electronic products are adding voice playback functionality, particularly battery-driven devices that require increased miniaturization and lower power consumption for longer operating life.

8-bit MCU with built-in 1 W Audio Amp – [Link]

1 May 2015

Micro Crystal RV8803C7

by Susan Nordyk @ edn.com:

Furnished in a ceramic surface-mount package that is just 3.2×1.5×0.8 mm, the RV-8803-C7 real-time clock module from Swiss manufacturer Micro Crystal consumes 240 nA and operates from a supply voltage as low as 1.5 V to increase the life of backup supplies. The device gives designers the option to replace expensive batteries and supercapacitors with low-cost multilayer ceramic capacitors for battery backup.

The temperature-compensated real-time clock is accurate to within ±3.0 ppm (±0.26 seconds/day) over a temperature range of -40°C to +85°C. In addition to low current consumption and high accuracy, the RV-8803-C7 has one of the smallest ceramic packages in the industry with an integrated 32.768-Hz quartz crystal. It operates from a supply voltage ranging from 1.5 V to 5.5 V and employs an I2C interface.

Tiny real-time clock consumes only 240 nA – [Link]

2 Apr 2015


by elektor.com:

The 17 mm square MM7150 Motion Module from Microchip Technology is a complete, small form-factor board containing a 3-axis accelerometer, 6-axis digital compass and gyroscope sensors pre-programmed with integrated calibration and sensor fusion algorithms. Connections to the board include I2C, power and ground. The board operates at 3.3 V and consumes about 7.68 mA in active mode and around 70 µA in deep sleep.

Read position & motion data over I2C
Small size 17×17
Pre-programmed and calibrated
Single sided – can be soldered down
SSC7150 motion coprocessor with integrated sensor fusion
9-axis Sensors (accelerometer, magnetometer, gyroscope)

Tiny Card Deals with your Motions – [Link]

18 Mar 2015


Martin’s DIY Internet connected smart humidifier project:

The project uses a DHT22 temperature sensor mounted to the side of the enclosure for better ventilation and reliable reading:
I threw in a ultra-cheap I2C OLED status display to get a visual reading. Milling the box so that the OLED shows was pretty nasty, hated it. I cut a piece of paper and placed it on top of the cover, below the transparent lid to cover up for the lousy milling job
The humidistat switches on and off the humidifier as needed, the humidifier itself is plugged in to a plug in the relay. The  auto detects when water is out and stops, so I didn’t have to care about that.

Internet connected smart humidifier – [Link]





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