PIC Microcontroller http://pic-microcontroller.com Microchip PIC Microcontroller Free Projects Tutorials Compilers Programmers Sample Code and Books on PIC Microcontroller Sun, 22 Apr 2018 05:38:23 +0000 en-US hourly 1 https://wordpress.org/?v=4.9.5 Biosensors with ECG function for heart rate monitoring in wearables http://pic-microcontroller.com/biosensors-ecg-function-heart-rate-monitoring-wearables/ http://pic-microcontroller.com/biosensors-ecg-function-heart-rate-monitoring-wearables/#respond Sun, 22 Apr 2018 05:38:23 +0000 http://pic-microcontroller.com/?p=14284 Silicon Labs has introduced a family of optical biometric sensors providing advanced heart rate monitoring (HRM) by transcutaneous optical measurements, along with electrocardiogram (ECG) capabilities, for a range of wearable fitness and wellness products. Si117x sensor modules combine ultra-low power, high sensitivity and integration, for smart watches and wrist-based, patch-type and other wearables requiring long […]

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Silicon Labs has introduced a family of optical biometric sensors providing advanced heart rate monitoring (HRM) by transcutaneous optical measurements, along with electrocardiogram (ECG) capabilities, for a range of wearable fitness and wellness products.
Biosensors with ECG function for heart rate monitoring in wearables

Si117x sensor modules combine ultra-low power, high sensitivity and integration, for smart watches and wrist-based, patch-type and other wearables requiring long battery life and enhanced HRM accuracy. To simplify development and speed time to market, Silicon Labs offers a complete, end-to-end sensing solution featuring the Si117x sensor module, HRM algorithm, Wireless Gecko SoCs for Bluetooth connectivity, and a wrist-based development kit with sample code and example projects.

All-day HRM, Silabs asserts, is a key requirement for health and fitness wearables; the Si117x sensors consume less than 50 µA (sensor and LED combined) while performing continuous HRM. A built-in buffer and accelerometer synchronization capabilities save even more system-level power. The sensors’ power efficiency enables developers to use smaller batteries in wearable designs without significantly impacting the device’s battery life during continuous monitoring.

The Si117x sensors provide enhanced HRM accuracy with fast sampling speeds, a high signal-to-noise ratio (SNR >100 dB), and the ability to cancel out ambient noise and erroneous data, resulting in high-quality signals that make it easier to track heart rates despite challenging physiologies, varying skin tones and the presence of tattoos. A more accurate view of the HR waveform enables biometrics beyond traditional HRM, including heart rate variability (HRV), stress analysis and pulse volume.

By combining ECG measurements with optical HR measurements, Silabs says, the Si117x sensors allow developers to unlock new potential biometrics for wearables. The ECG waveform is the gold standard for cardiac measurements, and the Si117x sensors bring this capability to wrist-based wearables in a cost-effective, power-efficient manner. By making measurements in the same device and at the same time, the Si117x sensors allow developers to combine biometrics with optical photoplethysmogram (PPG) measurements to derive physiological parameters.

Each module supports up to four discrete LEDs (all of which can be driven simultaneously), and its four LED drivers are independently programmable (from 1.7 to 310 mA). Additional built-in features include a photodetector.

Read More: Biosensors with ECG function for heart rate monitoring in wearables

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CONTACTLESS AUTOMATIC WARDROBE LED LIGHT WITH FADE EFFECT http://pic-microcontroller.com/contactless-automatic-wardrobe-led-light-fade-effect/ http://pic-microcontroller.com/contactless-automatic-wardrobe-led-light-fade-effect/#respond Sat, 21 Apr 2018 05:28:49 +0000 http://pic-microcontroller.com/?p=14281 Contact-less controlled automatic wardrobe light turns on the LED when you open the wardrobe door. Τhe project is based on Hall effect IC including LED driver and tiny magnet. Board doesn’t require any mechanical switch. When magnet is close to the board, LED is off, when you open the wardrobe door magnet goes far from […]

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Contact-less controlled automatic wardrobe light turns on the LED when you open the wardrobe door. Τhe project is based on Hall effect IC including LED driver and tiny magnet. Board doesn’t require any mechanical switch. When magnet is close to the board, LED is off, when you open the wardrobe door magnet goes far from hall IC and its turn on the LED, the IC also has special features like soft start and soft off. This board can be used in other applications like Automotive Gloves boxes and Storage, task lighting, automotive vanity mirrors.  The APS13568 is the heart of the project. The IC can drive LED current up to 150mA. I have set the current 100mA approx. with help of R3. C2 is provided to set the FADE-IN/FADE-OUT time. The value of C2 can be changed as per application requirement.

CONTACTLESS AUTOMATIC WARDROBE LED LIGHT WITH FADE EFFECT

The IC is an integrated circuit that combines an ultrasensitive, Omni polar, micro power Hall-effect switch with a linear programmable current regulator providing up to 150 mA to drive high brightness LEDs. The Omni polar Hall Effect switch provides contactless control of the regulated LED current, which is set by a single reference resistor R3. This highly integrated solution offers high reliability and ease of design compared to a discrete solution. The Hall-effect switch operates with either a north or a south magnetic pole. The switch output polarity can be set with an external pull down on the POL input pin. This allows the user to select whether the APS13568 switch output goes low when a magnet is present or when the magnetic field is removed. Chopper stabilization provides low switch point drift over temperature. The LED is turned on when the EN input goes low. This active low input can be connected directly to the Hall switch output, SO, to turn the LED on when the switch output goes low. This flexible solution allows the user to connect additional slave switches, LED drivers, PWM, or microprocessor inputs to control when the LED is on. Optionally, an external capacitor can be used to adjust the fade-in/fade-out feature. On-board protection for shorts to ground and thermal overload prevents damage to the APS13568 and LED string by limiting the regulated current until the short is removed and/or the chip temperature has reduced below the thermal threshold. The integrated Hall-effect switch in the APS13568 is an Omni polar switch. The output switches when a magnetic field perpendicular to the Hall sensor exceeds the operate point threshold, BOPx (B > BOPS or B < BOPN). When magnetic field is reduced below the release point, BRPx (B < BRPS or B > BRPN), the device output goes to the other state. The output transistor is capable of sinking current up to the short-circuit current limit, IOM, which ranges from 30 to 60 mA. The difference in the magnetic operates and release points are the hysteresis, BHYS, of the device. This built-in hysteresis allows clean switching of the output even in the presence of external mechanical vibration and electrical noise. Removal of the magnetic field results in an output state consistent with B < BRPx. Since the output state polarity relative to the magnetic thresholds is user-selectable via the POL pin, reference Table 1 to determine the expected output state.

Note: The board has omnidirectional Hall sensor. Default it set to switch on the LED in absence of magnetic field or magnet is not around, it will switch off the LED when magnet is close to the hall sensor IC or in presence of magnetic field. Remove POL Resistor R4 for reverse operation.

Read More: CONTACTLESS AUTOMATIC WARDROBE LED LIGHT WITH FADE EFFECT

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Time-Controlled Switch Using PIC16F72 http://pic-microcontroller.com/time-controlled-switch-using-pic16f72/ http://pic-microcontroller.com/time-controlled-switch-using-pic16f72/#respond Fri, 20 Apr 2018 10:28:42 +0000 http://pic-microcontroller.com/?p=14755 A time controlled switch is an automatic timer switch that turns an appliance ‘on’ for the desired time duration. After the preset time duration, the timer automatically switches off, disconnecting the appliance from the power supply. The time duration for which the appliance should be ‘on’ can be set from 1 to 99 minutes. This […]

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A time controlled switch is an automatic timer switch that turns an appliance ‘on’ for the desired time duration. After the preset time duration, the timer automatically switches off, disconnecting the appliance from the power supply. The time duration for which the appliance should be ‘on’ can be set from 1 to 99 minutes.

This switch obviates the need to continuously monitor the appliance—an advantage over the manual switch. It can be used to switch on or switch off any electrical home appliance at a predetermined time. Switching an appliance on or off in a timely manner increases the life of the appliance and also saves power consumption.

The switch also finds industrial applications, where the machines which control the processes can be run for the desired time.

Time controlled switch circuit

Fig. 1 shows the circuit of the time controlled switch using PIC16F72 microcontroller. It comprises microcontroller PIC16F72 (IC1), regulator 7805 (IC2), two 7-segment displays//electronicsforu.com/resources/7-segment-display-pinout-understanding(LTS542) and a few discrete components.

Microcontroller PIC16F72 is the heart of this time controlled switch. It is an 8-bit, low-cost, high-performance, flash microcontroller. Its key features are 2 kB of flash program memory, 128 bytes of RAM, eight interrupts, three input/output (I/O) ports, three timers and a five-channel 8-bit analogue-to-digital converter (ADC). There are 22 I/O pins, which are user-configurable for input/output on pin-to-pin basis. Architecture is RISC, and there are only 35 powerful instructions.

System clock plays a significant role in operation of the microcontroller. A 4MHz quartz crystal connected between pins 9 and 10 provides the basic clock to the microcontroller (IC1).

Two 7-segment displays (DIS1 and DIS2) are used to display the time in minutes. Port pins RB2, RB3, RA0, RA1, RA2, RB1 and RB0 are connected to segment pins ‘a’ through ‘g’ of display DIS1, respectively. Ports pin RC6, RC7, RC1, RC2, RC3, RC5 and RC4 are connected to segment pins ‘a’ through ‘g’ of display DIS2, respectively.

Switches S2 (start/stop), S3 (select), S4 (decrement) and S5 (increment) are connected to port pins RB4 through RB7 of the microcontroller, respectively. Port pin RC0 of the microcontroller is used to control relay RL1 with the help of transistor T1. When port pin RC0 is high, transistor T1 drives into saturation and 12V-relay RL1 energises to connect the load to power supply. Diode D5 acts as a free-wheeling diode.

Circuit Operation

To derive the power supply for the circuit, the 230V, 50Hz AC mains is stepped down by transformer X1 to deliver a secondary output of 12V, 500mA. The transformer output is rectified by a full-wave rectifier comprising diodes D1 through D4, filtered by capacitor C4 and regulated by IC 7805 (IC2). Capacitor C5 is used to bypass the ripples present in the regulated supply. LED2 gives power-‘on’ indication. Resistor R19 limits the current through LED2. Switch S1 is used for manual reset.

Set the time using switch S4 for decrement and switch S5 for increment. The time is indicated on 7-segment displays DIS1 and DIS2. To start timing count-down, press start/stop switch S2. Relay RL1 energises to switch on the appliance and LED1 glows. If you press start/stop switch S2 again, the count-down process will stop and relay RL1 de-energise to switch the appliance off.

Construction and working

A single-side PCB for the microcontroller-based time controlled switch is shown in Fig. 2 and its component layout in Fig. 3.

Fig. 2: An actual-size, single-side PCB for the time-controlled switch using PIC16F72
Fig. 2: A single-side PCB for the time controlled switch using PIC16F72
Fig. 3: Component layout for the PCB
Fig. 3: Component layout for the PCB

Download PCB and component layout PDFs: click here

Assemble the circuit on a PCB to minimise time and assembly errors. Carefully assemble the components and double-check for any overlooked error. Use an IC base for microcontroller. Before inserting the IC, check the supply voltage.

The time controlled switch works in two modes: setting mode (to set the time from 1 to 99 minutes) and working mode (to drive the load for the desired time as per the setting). The modes can be changed using switch S3. When LED1 glows, it indicates that the system is in working mode. If LED1 is off, the system is in setting mode.

Setting mode

By default, when the microcontroller is powered up, it is in setting mode. In this mode, one of the two 7-segment displays should blink with a random digit, say, 6. You can change the blinking digit to any digit from 0 through 9 using decrement switch S4 or increment switch S5. You can also shift the blinking digit from DIS1 to DIS2 or vice-versa using switch S3. Thus the desired time can be set using switches S3, S4 and S5.

After setting the desired time, press start/stop switch S2 to switch from setting mode to working mode. The appliance will turn on for the preset time unless you press switch S2 again to stop the operation in between.

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To Build the World’s Smallest Atomic Clock, Trap a Nitrogen Atom in a Carbon Cage http://pic-microcontroller.com/build-worlds-smallest-atomic-clock-trap-nitrogen-atom-carbon-cage/ http://pic-microcontroller.com/build-worlds-smallest-atomic-clock-trap-nitrogen-atom-carbon-cage/#respond Fri, 20 Apr 2018 05:01:05 +0000 http://pic-microcontroller.com/?p=14273 The Norwegian explorer had set a new record for the closest approach to the North Pole, and now he was moving quickly over unbroken sea ice toward Cape Fligely and home. But then came a sickening realization: In his eagerness to break camp, he had forgotten to wind the chronometers. He had lost track of […]

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The Norwegian explorer had set a new record for the closest approach to the North Pole, and now he was moving quickly over unbroken sea ice toward Cape Fligely and home. But then came a sickening realization: In his eagerness to break camp, he had forgotten to wind the chronometers. He had lost track of precise time, and thus the ability to track his longitude.

Although Nansen couldn’t have lost his position by more than a few minutes, it forced him to take a circuitously conservative route to avoid being swept into the North Atlantic. His expedition thus had to endure a hungry winter, camped on an unknown shore. Not until June the following year did he encounter other explorers and learn his true position—on Cape Felder, in Franz Josef Land.

To Build the World’s Smallest Atomic Clock, Trap a Nitrogen Atom in a Carbon Cage

Today, anyone with a smartphone can determine their time and position with ease. Satellites of the Global Positioning System (GPS) broadcast clock signals across the globe with uncertainties below 100 nanoseconds, or one ten-millionth of a second. These time signals carry the information needed for precise navigation: Because radio waves travel at exactly 0.299,792,458 meters per nanosecond (apart from minuscule variations due to refraction in the atmosphere), comparing signals from different satellites makes it possible to determine a position within a few meters. That’s why GPS has transformed seismic monitorsdrone delivery, and many other applications.

But GPS can’t solve all timing problems. Central to the system are atomic clocks carried on each satellite. Although these clocks are extremely stable (and regularly calibrated by comparing them with ground-based atomic clocks at national standards laboratories), there are many ways to go wrong when transferring timing information to the user—jamming, spoofing, unintentional interference, solar storms, even reflections from buildings. But what if we could put this precision directly in the hands of the user by shrinking the atomic clock itself so it could work inside the GPS receiver? Would we, like Nansen, then want to carry our very best clocks with us?

In research now published at Physical Review Letters, we show that such a mobile clock is possible. We hope to make one soon.

The core of an atomic clock is a vacuum chamber containing a thin cloud of vaporized metal, usually cesium. Atoms in the vapor resonate at a precise frequency, meaning that their electrons will accept energy only from photons having just the right amount of it. If those photons have a little too much or too little energy—that is, if their frequency is a little too high or too low—the absorption falls off markedly. This is the key feature of an atomic clock.

Here’s how it works. An electrical oscillator creates a microwave frequency very close to the energy level of the atom we are using for our clock. If the oscillator deviates slightly from the correct frequency, the absorption changes, the change is detected by a laser, and the laser’s signal is used to tune the oscillator. This feedback loop corrects the oscillator’s imperfections.

Unlike the pendulum of a clock or the mechanical mechanism of a watch, atoms do not suffer from manufacturing error or wear; with proper isolation from the environment, their resonant frequency is set by the laws of physics. Achieving the necessary level of isolation in practice means that the best atomic clocks take up entire rooms. Commercial atomic clocks are usually the size of suitcases.

In 2004, in a tour de force of microfabrication, scientists at the National Institute of Standards and Technology managed to shrink this entire setup into a stack of components a few millimeters high. Such “chip-scale” atomic clocks are now available commercially and are used in niche applications, such as military communications and underwater navigation. But this miniaturization comes at a price—

Back to the atomic clock: We start with an oscillator that generates a radio signal close to the frequency that the nitrogen will absorb. We transmit the signal via an antenna to a cell containing a sample of the molecules, either as a powder or in solution. If the oscillator is correctly tuned, power is absorbed. If we see a reduction in the absorbed power, we’ll know that the oscillator has drifted away from the target frequency. Using a feedback mechanism, the oscillator can then be tuned back to the point of maximum absorption. Because this frequency is precisely known, an accurate time reference follows by simply counting cycles of the stabilized oscillator. We manage the feedback by modulating the oscillator frequency and having the detector look at that modulation. If the oscillator is set correctly, the modulation of the output is zero; if the oscillator’s central frequency has deviated, the sign of the output modulation tells us which side of the resonance it has moved to.

Endohedral fullerenes such as N@C60 are outstanding reference materials because, as we showed in 2006, the transitions between their quantum-mechanical spin states have some of the most precisely delineated frequencies of any molecule. If you draw a graph of the materials’ response to stimulating radiation, it will show a very narrow peak at the resonant frequency. Also, the fullerene cage prevents the walls of the container from affecting the frequency. One external influence does, however, penetrate the fullerene cage and can alter the relevant frequencies: a magnetic field. Because the world is full of uncontrolled magnetic fields—for example, from electric motors, steel vehicles, and Earth itself—protection from them is crucial for a stable clock. What Briggs and Ardavan realized is that for the N@C60 molecule, applying a small, static magnetic field can tune the energy levels in such a way that all magnetic influences on the resonance frequency cancel each other out.

The point, of course, is to one day incorporate a complete atomic clock into one chip. In this design, the entire operation is based on radio-frequency electronics, avoiding the need for optical elements, as used in conventional atomic clocks. And unlike a vapor-based clock, there would be no need to maintain a vacuum chamber and no power-hungry heater to drain a battery. An endofullerene-based atomic clock could thus be small, light, and energy efficient. Potentially, it could replace many of the quartz oscillators used in nearly every present-day electronic device to keep time.

Read More: To Build the World’s Smallest Atomic Clock, Trap a Nitrogen Atom in a Carbon Cage

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Exploring the Open Source Ethernet Broadcaster http://pic-microcontroller.com/exploring-open-source-ethernet-broadcaster/ http://pic-microcontroller.com/exploring-open-source-ethernet-broadcaster/#respond Thu, 19 Apr 2018 10:51:15 +0000 http://pic-microcontroller.com/?p=14268 In this second and final post we will go deep inside the Ethernet audio streaming transceiver firmware. Recently, we have presented an Ethernet audio streaming unit. In particular, we have shown how to configure the boards to work with other similar devices or with VLC Media Player, setting up a point-to-point or a broadcast streaming in all […]

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In this second and final post we will go deep inside the Ethernet audio streaming transceiver firmware.

Recently, we have presented an Ethernet audio streaming unit. In particular, we have shown how to configure the boards to work with other similar devices or with VLC Media Player, setting up a point-to-point or a broadcast streaming in all possible configurations. Also in the first episode, we analyzed the electrical circuit and the components choice. Now it is time to describe the board software advanced options and how to update firmware via Internet or manually.

Exploring the Open Source Ethernet Broadcaster

AUTHENTICATION AND LOCAL NETWORK

In the Authentication page, you can change your credentials to access all the restricted areas. The software allows two roles, each accessible with username and password. The software recognizes as Admin the role with the highest level of administrator privileges, only it can change all available settings; instead the role with less rights is simply “User”. When you login as administrator in the Authentication page, you get a form (first figure), where you can change your credentials; similarly, when you login as user (as in second figure) you can change the user role settings only.

In this second and final post we will go deep inside the Ethernet audio streaming transceiver firmware.

Recently, we have presented an Ethernet audio streaming unit. In particular, we have shown how to configure the boards to work with other similar devices or with VLC Media Player, setting up a point-to-point or a broadcast streaming in all possible configurations. Also in the first episode, we analyzed the electrical circuit and the components choice. Now it is time to describe the board software advanced options and how to update firmware via Internet or manually.

 

AUTHENTICATION AND LOCAL NETWORK

In the Authentication page, you can change your credentials to access all the restricted areas. The software allows two roles, each accessible with username and password.

Read More: Exploring the Open Source Ethernet Broadcaster

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AMSAT MPPT http://pic-microcontroller.com/amsat-mppt/ http://pic-microcontroller.com/amsat-mppt/#respond Wed, 18 Apr 2018 10:46:08 +0000 http://pic-microcontroller.com/?p=14265 Maximum Power Point Tracking Let’s cover the basics first. A Maximum Power Point Tracker is an intermediate circuit placed between a solar panel and the load being powered. Solar panels produce the maximum amount of power at a specific voltage which varies with light irradiance as well as board temperature. The MPPT interfaces the solar panel with […]

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Maximum Power Point Tracking

Let’s cover the basics first. A Maximum Power Point Tracker is an intermediate circuit placed between a solar panel and the load being powered. Solar panels produce the maximum amount of power at a specific voltage which varies with light irradiance as well as board temperature. The MPPT interfaces the solar panel with the load in such a way that the conditions for maximum power are always met when needed. In the case of RadFxSat the MPPT is temperature based since most of the change occurs with solar panel temperature and much smaller effects are created by irradiance from the Sun. Read the Fox-1 MPPT Technical Document if you are interested in the details of how the Fox-1 MPPT works.

AMSAT MPPT

It All Started at RIT

During the Dayton Ohio Hamfest in May 2012 Anthony Montiero, AA2TX, agreed to sponsor a senior design project for us during the next academic year at the Rochester Institute of Technology. Tony was the Vice President of AMSAT engineering at the time. He wanted us to design a new Maximum Power Point Tracker that could be used by AMSAT on future missions which were flying higher power radios and larger scientific payloads. The original intent was to fly this MPPT on a 3U cubesat named Fox-2.

The senior design team consisted of just four students: Ian Mackenzie (KB3OCF), Dan Corriero, Brenton Salmi (KB1LQD), and myself (KB1LQC). We had chosen to work together as we were all members of K2GXT, the RIT Amateur Radio Club, and had recently built and launched RITchie-1 (a high altitude balloon) together. We were guided by two Rochester, NY area engineers, Vincent Burolla and Leo Farnand, who had agreed to help us out and were obviously skeptical of the pure amount of work we had signed-up for. However, our team was motivated and ready for the challenge.

P13271: AMSAT Maximum Power Point Tracker

At the time RIT was still on the quarter system which meant that the two quarter Senior Design course only gave us 20 weeks to design, build, and test a working MPPT. Every one of us still had normal coursework and were active members of K2GXT. Great lessons of descoping projects, good communication, and teamwork were tested during this time. I vividly remember being one of the only teams who would put feelings aside in effort to make quick progress. For example, we never perfected our documentation before sending it to our guides. Instead our team wanted their feedback as soon as possible if were unsure about something. We knew we could do it but we also knew that we were learning and acknowledging that let us focus on the goal of getting an analog MPPT designed, built and tested in such a short time-frame.

Read More: AMSAT MPPT

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36V, 2-ch, 1.6A synchronous buck LED driver has I²C dimming http://pic-microcontroller.com/36v-2-ch-1-6a-synchronous-buck-led-driver-i%c2%b2c-dimming/ http://pic-microcontroller.com/36v-2-ch-1-6a-synchronous-buck-led-driver-i%c2%b2c-dimming/#respond Tue, 17 Apr 2018 10:34:56 +0000 http://pic-microcontroller.com/?p=14262 Under the “Power by Linear” branding it recently created for the product lines it acquired with its purchase of Linear Technology, Analog Devices has added the LT3964, a dual channel, 36V, high efficiency, synchronous, step-down LED driver with internal 40V, 1.6A power switches and an I2C interface that simplifies LED dimming control. The LT3964 operates […]

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Under the “Power by Linear” branding it recently created for the product lines it acquired with its purchase of Linear Technology, Analog Devices has added the LT3964, a dual channel, 36V, high efficiency, synchronous, step-down LED driver with internal 40V, 1.6A power switches and an I2C interface that simplifies LED dimming control.
36V, 2-ch, 1.6A synchronous buck LED driver has I²C dimming

The LT3964 operates with a 4V to 36V input range, and features two independently controlled LED drivers that switch at up to 2 MHz, resulting in a highly integrated, compact solution with small external components.

 

The LT3964 employs fixed frequency, current mode control and operates as a constant-current and constant-voltage source with accurate current regulation to provide optimal LED lighting in automotive, industrial and architectural lighting applications. Synchronous operation results in efficiencies above 94% with both channels at full current load.

 

Its 400 kHz I2C interface simplifies digital PWM dimming. A PWM signal from a microcontroller to the LED driver is not necessary; instead, internal registers are programmed with the desired dimming duty cycle, which is synchronized to the internal clock. This provides dimming ratios up to 8192:1 and eliminates beat frequencies caused when the PWM signal and the internal oscillator are not synchronized. Alternatively, with analogue dimming, an I2C settable 8-bit scale factor sets the control voltage-to-LED current ratio allowing more control of analogue dimming adjustments. 1000:1 external PWM dimming and 10:1 analog dimming are also provided.

 

The LT3964’s switching frequency is programmable from 200 kHz to 2 MHz or it can be synchronized to an external clock signal. LED driver protection features include open LED and short-circuit LED fault detection, and LED overcurrent and overvoltage detection, all of which can be reported via the I2C interface. Thermal shutdown provides an added layer of protection.

 

The LT3964EUHE is available in a thermally enhanced 36-lead 5 x 6 mm QFN package. Three temperature grades are available, with operation from –40°C to 125°C (junction) for the extended and industrial grades, and a high temperature grade of –40°C to 150°C. Pricing is from $4.50 (1000).

Read More: 36V, 2-ch, 1.6A synchronous buck LED driver has I²C dimming

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ROBOBEE – A FLYING MICROBOT THAT CAN PERFORM SEARCH AND RESCUE MISSIONS http://pic-microcontroller.com/robobee-flying-microbot-can-perform-search-rescue-missions/ http://pic-microcontroller.com/robobee-flying-microbot-can-perform-search-rescue-missions/#respond Mon, 16 Apr 2018 10:19:15 +0000 http://pic-microcontroller.com/?p=14259 Inspired by the biology of a bee, researchers at the Wyss Institute developed RoboBees, man-made microbots that could perform endless roles in agriculture or disaster relief. A RoboBee is about half the size of a paper clip, weighs less than one-tenth of a gram, and flies using materials that contract when an electric pulse is applied. Now, they progressed […]

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Inspired by the biology of a bee, researchers at the Wyss Institute developed RoboBees, man-made microbots that could perform endless roles in agriculture or disaster relief. A RoboBee is about half the size of a paper clip, weighs less than one-tenth of a gram, and flies using materials that contract when an electric pulse is applied. Now, they progressed even further and designed a hybrid RoboBee that can fly, dive into water, swim, propel itself back out of the water, and safely land.

ROBOBEE – A FLYING MICROBOT THAT CAN PERFORM SEARCH AND RESCUE MISSIONS

 

New floating devices allow this multipurpose air-water microrobot to stabilize on the water’s surface before an internal combustion system ignites to propel it back into the air. This latest-generation RoboBee is 1000 times lighter than any previous aerial-to-aquatic robot. This can be used for numerous applications, from search-and-rescue operations to environmental monitoring and biological studies. Yufeng Chen, Ph.D. and a Postdoctoral Fellow at the Wyss Institute, said:

This is the first microrobot capable of repeatedly moving in and through complex environments

The researchers have faced numerous challenges to design a millimeter-sized robot that moves in and out of the water. The robot’s wing flapping speed will vary widely between the two mediums as water is 1000 times denser than air. If the flapping frequency is too low, the RoboBee can’t fly. If it’s too high, the wing will snap off in the water. So, it requires a precise balancing as well as a smart multimodal locomotive strategy to overcome this problem.

RoboBee has four buoyant outriggers and a central gas collection chamber. Once the RoboBee swims to the surface, an electrolytic plate in the chamber converts water into oxyhydrogen, a highly combustible gas fuel. The gas increases the robot’s buoyancy and pushes the wings out of the water. The outriggers stabilize the RoboBee on the water’s surface. Elizabeth Farrell Helbling, a graduate student in the Microrobotics Lab, said:

Because the RoboBee has a limited payload capacity, it cannot carry its own fuel, so we had to come up with a creative solution to exploit resources from the environment.

Read More: ROBOBEE – A FLYING MICROBOT THAT CAN PERFORM SEARCH AND RESCUE MISSIONS

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LED HEART KEYCHAIN http://pic-microcontroller.com/led-heart-keychain/ http://pic-microcontroller.com/led-heart-keychain/#respond Sun, 15 Apr 2018 10:12:32 +0000 http://pic-microcontroller.com/?p=14256 This one is a very simple but cool project, something that I would recommend to anyone who is interested into DIY electronics, gadgets and learning new stuff in general. It is definitely one of those projects that don’t require too much time but you can learn a lot by making it and also earn a […]

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This one is a very simple but cool project, something that I would recommend to anyone who is interested into DIY electronics, gadgets and learning new stuff in general. It is definitely one of those projects that don’t require too much time but you can learn a lot by making it and also earn a lot of credit by sharing it with your friends and family.

LED HEART KEYCHAIN

Below you can see a final product. It’s a heart shaped, touch sensitive, keychain for your loved ones. On the front side there is a smiley face drawing that has eyes and mouth. Eyes have two red LEDs that will start to pulse once you touch the keychain or place you finger on the smiley face (see it in action below)

On the back side there is a battery holder for coin cell battery, microcontroller (MCU) and four passives to support the MCU and front LEDs.

Components that you will need for this project

PIC12LF1822 Microcontroller, the brain behind our device
CR2016 for providing power to our device
4.7uF capacitor, two 200 Ohm resistors and 2 RED LEDs. All with footprint 0603 (imperial)

Detailed BoM is attached with rest of the source files.

Let’s see how this thing actually works

We want to detect when someone is interacting with our keychain and when that happens we will turn on the LEDs to signify something like “I love you”, “I miss you” or anything else that you want. Since this is a keychain first, it has to look and feel nice. Putting a tactile button would sure make our life easy but it would also make device bulky and ugly, and we don’t want that. So instead of using a tactile button, we are going to use touch sensor aka cap sense. Basically same thing that you have in phones touch screen, payment terminals and etc.

Read More: LED HEART KEYCHAIN

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HEARTYPATCH – OPEN SOURCE ECG PATCH WITH WIFI http://pic-microcontroller.com/heartypatch-open-source-ecg-patch-wifi/ http://pic-microcontroller.com/heartypatch-open-source-ecg-patch-wifi/#respond Sat, 14 Apr 2018 10:02:11 +0000 http://pic-microcontroller.com/?p=14253 HeartyPatch is a completely open source, single-lead, ECG-HR wearable patch with HRV (Heart Rate Variability) analysis. It is based on the popular ESP32 system-on-a-chip. By using low-cost, highly-integrated components, we are able to keep the BOM’s cost low, while the simplicity of the circuit design means future expansion will be easier. HeartyPatch can be used […]

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HeartyPatch is a completely open source, single-lead, ECG-HR wearable patch with HRV (Heart Rate Variability) analysis. It is based on the popular ESP32 system-on-a-chip. By using low-cost, highly-integrated components, we are able to keep the BOM’s cost low, while the simplicity of the circuit design means future expansion will be easier. HeartyPatch can be used both as a lifestyle device for managing fitness and stress as well as for diagnostics and medical research, with the potential for even more interesting applications.

HEARTYPATCH – OPEN SOURCE ECG PATCH WITH WIFI

Currently available low-cost, wearable heart monitors are usually based on less accurate optical measurements while the actual electrocardiography-based monitors are either too expensive or difficult to use. Similarly, heart-rate variability (HRV) data is used in fitness and training, but can also be used to detect some of the basic cardiac arrhythmias. Getting accurate R-R intervals for HRV studies is also tricky with most heart-rate monitors.

What is Heart-rate Variability?

Heart-rate variability, or HRV, is a measure of the variance of heart-rate in real-time. More specifically, it is the time difference between two R-R intervals (the signal peaks) in an electro-cardiogram (ECG or EKG) plot.

Studies of heart-rate variability have shown that HRV can be indicative of some common forms of arrhythmia, including atrial fibrillation (AF) and atrial tachycardia (AT), among others. HRV can be detected with a single lead ECG, like HeartyPatch, which, for cardiac patients being monitored for such forms of arrhythmia, is much easier to wear long term than a full Holter configuration (three or five leads).

In fitness applications, some high-performance athletes train using biofeedback for heart-rate control and also for knowing when to start and stop training (based on heart-rate).

HRV has also be known to reflect emotion, mood, anxiety, and stress. When such psychological events happen, there is a known pattern of variance in heart rate. This makes HRV useful tool for studying mood and managing stress in people who are prone to such psychological states.

Finally, since HeartyPatch can detect individual heart-beats in real-time, it can also be used in the areas of design and non-medical wearables to detect heart beats to activate lights or any other form of feedback. Cardio-biofeedback is an example of controlling heart-rate.

Who Needs HeartyPatch

  • Medical professionals, caregivers, and researchers (for continuous event monitoring)
  • High performance sports and fitness professionals (for precision cardio training)*
  • Hardware/software developers (as a reference design)
  • Curious poeple (because knowing your own heart-patterns is cool)

*Activities that cause sweating can prevent adhesive electrodes from adhering properly.

Read More: HEARTYPATCH – OPEN SOURCE ECG PATCH WITH WIFI

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