Tag Archives: I2C

8T49N004 Programmable Femtoclock® NG with 4-outputs

This design features a fourth generation programmable femtoclock that provides reference frequencies to replace crystals and SAW oscillators in high-performance applications. It is programmable through I2C interface. It has four selectable LVPECL or LVDS via I2C while its FemtoClock NG VCO ranges between 1.9GHz to 2.55GHz. It also meets the standard interface requirements of PCI Express (2.5Gb/s), Gen 2 (5Gb/s), and Gen 3 (8Gb/s) jitter that are low in both clock synthesizers and phase-locked oscillators.

The design is comprised of few components that can be divided into three main areas. First, the I2C interface area that uses optoisolator to ensure the compatibility of the external I2C device to the main clock frequency synthesizer. Second, the main part where the IDT8T49N004I clock generator generates the clock with selectable LVDS or LVPECL outputs. Lastly, the power supply of the device uses a low noise Low DropOut (LDO) regulator that is optimized for fast transient response. It also makes use of reference diodes and capacitor filters that secure the system from possible noise produced from the supply.

The design is applicable to several applications that requires reference clock especially network processors and Application-Specific Integrated Circuits (ASICs). It can improve the overall performance of the device since it makes the device more immune to noise and other undesired system behavior.

8T49N004 Programmable Femtoclock® NG with 4-outputs – [Link]

ESP8266 MQTT battery monitor project


Steve’s latest project, a wireless MQTT battery monitor:

This board uses an ESP8266 (ESP12), a Texas Instruments INA226 I2C voltage and current monitor, and a Texas Instruments LMR12010X buck converter. This board is designed to wirelessly monitor 12 volt batteries and power supplies using an external current shunt resistor. The voltage across the shunt resistor is measured differentially. The shunt resistor value and current rating is programmable in the firmware.

ESP8266 MQTT battery monitor project – [Link]

Buck battery charger handles multiple chemistries


by Susan Nordyk @ edn.com:

The LTC4015 synchronous step-down battery charger controller from Linear Technology offers charge current of up to 20 A, multiple-chemistry operation, and onboard digital telemetry. The controller transfers power from a variety of input sources, such as wall adapters and solar panels, to a Li-Ion polymer, LiFePO4, or lead-acid battery stack with system load up to 35 V.

Operating over an input voltage range of 4.5 V to 35 V, the LTC4015 provides ±5% charge-current regulation up to 20 A and ±0.5% charge-voltage regulation. While a host microcontroller is required to access the most advanced features of the LTC4015, the use of an I2C port is optional.

Buck battery charger handles multiple chemistries – [Link]

IO expander board


I/O Expander Board offers a convenient way to interface upto 16 I/O pins in your project using SPI/I2C bus.  This kit uses the famous MCP23S17 IO chip from Microhip.


  • Supply sourced through the interfacing Box Header connector
  • The kit has 2 separate Box Header type connector for the 16 pins of I/O port and 1 Box Header for interfacing of the PCB with the host controlling circuit
  • Jumper selectable address option is also available for this kit
  • Four mounting holes 3.2 mm each
  • PCB dimensions 58 mm x 54 mm

IO expander board – [Link]



EEPROM Add-On Board offers an easy way to interface a standard 24Cxx type I2C EEPROM to your project.


  • 5 VDC supply sourced through the interfacing Box Header connector
  • Jumper selectable address option available
  • Four mounting holes 3.2 mm each
  • PCB dimensions 36 mm x 32 mm

EEPROM Module – [Link]

16-Bit I2C-Bus LED Dimmer

This project is devised for LED dimming using NXP Semiconductors’ PCA9532 16-Bit I2C-Bus LED dimmer. A lot of solid-state lighting applications require control over the emitted intensity of light for both functional and aesthetic requirements. Some of these applications also require a full dimming capability from fully ON to fully OFF. LED dimming potentially improves light source efficacy and lifetime.

The PCA9532 is an IC that is designed for controlling 16 LEDs over and I2C bus. It also includes the logic to act as an I2C slave device as well as the drive capability for directly driving LEDs. As well as being able to switch each of the LEDs ON and OFF independently, the PCA9532 also has two fully programmable PWM controllers that can be used to control up to 16 LEDs. Each PWM channel has a programmable period ranging from 0.6Hz to 152Hz, and a programmable duty cycle from 0-100%. This means the LEDs can be set to blink steadily and visibly, or dimmed. In this circuit, 13 LEDs are connected on pins LED0-LED12. The 1kΩ pull resistors required are fitted to the 5V supply. Once programmed, the internal oscillator allows the I2C bus to be disconnected from the PCA9532 with the LED continuing to be dimmed, something not possible with normal GPIOs. This enables electronics manufacturers to have supplementary LED dimmers in their systems, while freeing up the microcontroller and the I2C bus for more efficient operation of the system.

The I2C are targeting applications ranging from mobile phones to servers in computing, communication, and networking applications. Having a frequency range of 160Hz to once every 1.6 seconds, with a duty cycle range of completely off to 99.4% on allowing both dimming and blinking of LEDs. These new 2-, 4-, 8-, and 16-bit devices allow designers an easy way to build systems with more dimming LEDs than previously possible using just basic General Purpose I/Os (GPIO) or microcontrollers (MCUs). Manufacturers of applications such as cellphones and servers are increasingly requiring multiple blinking and dimming LEDs for eye-catching keypad lighting applications, as well as practical purposes such as status indication. The new PCA953x LED Dimmers allows more system flexibility by off-loading the LED power consumption and by eliminating the programming of the MCU.

16-Bit I2C-Bus LED Dimmer – [Link]

Automatic Pet Feeder

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]

App note: Low cost I2C level translator


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]

LabNation SmartScope: unique multi-platform USB oscilloscope


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]

Single-cell 5-A Li-Ion battery charger with MaxCharge™ technology



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]