LED indicator in a smartphone for what. LED seven indicators. Schemes with additional keys

It was the other day in the electronics store. Sometimes it appears various used radio components at a low price. This time I saw a chip, because I was worth a penny bought without thinking. I decided to make a simple mono indicator. Why mono, not stereo? Because the microcircuit is only one. The second channel is completed then ...

Printing with laser printer On glossy paper, the scheme, proceed to the transfer of toner (paint) on the fee. We do that in the following way: We put paper on a well-shined sandpaper fee and heated iron for 10 minutes drive. We wait until the board cool down and remove the paper under hot water. The following should happen:

Then determine the fee in the chlorine gland. In about an hour, I spent completely fee. With the help of a solvent, getting rid of paint and the sandpaper give the board a more rectangular view.

Ludim fee. After proceeding with the soldering of parts. First hit the chip. After the LEDs, and then the remaining details. Full photo of the finished board:

Work scheme

Briefly tell about the appointments of the details. Using R2, configure the input level. Through the C1 condenser, the signal enters the VT1 transistor database that serves as an amplifier. Resistor R3 sets offset to the transistor base. Further stressed signal Through the C2 capacitor "comes" to diodes VD1 and VD2.

The negative signal is on minus, positive on the 5th leg of the chip. C3 and R4 serve as a filter. The higher the voltage on the 5 leg, the more LEDs light up. By the way, if you close 9 legs on plus, the LEDs will light up linearly. You can see the video as this thing works.

Video work LED indicator

Light Manager.. At that moment, when you comes a letter or message, your phone will try to attract your attention using the built-in indicator. But at the flickering of the LED, you never define what an event happened, and you still have to take it in hand. As long as you do not install Light Manager.

Light Manager is a program for Android, which will help you customize the work of the LED indicator of your gadget. With this application, you teach it to respond with different colors to certain events, such as the arrival of a new message in WhatsApp or an event from your calendar.

By default, the program already contains a number of settings for the most popular events. But you can remove the signals irrelevant for you at any time and add the necessary one. To do this, simply touch the desired item, and you will fall in the notification setup menu. Here you can set the frequency of the blink, choose the color of the LED and immediately check in the action of the settings you put.

If the program, notifications you want to receive, is missing in the list, then you can add it yourself. To do this, switch to alternative mode of operation Light Manager, and then select "Add Appendix". You will have a list of all programs installed on your smartphone. Choose need app And add a LED notification for it.

Please note that Light Manager can report not only about software, but also about various system events. For example, an application may notify you of a low battery charge, the absence of a network signal or switching on the quiet mode. It will not be superfluous to look into the advanced program settings, where you can set the frequency of the signal, turn on the sleep mode (time of day when Light Manager will not disturb you) and change the time automatic shutdown LED activity.

Setting LED indicator For notifications about different events:

Download Light Manager app on Android You can link below.

Developer: MC Koo
Platform: Android ( Depends on the device)
Interface language: Russian (RUS)
Condition: Full (full version)
Root: do not need

In the lesson, we learn about the schemes for connecting seven-segment LED indicators to microcontrollers, about indicator management methods.

LED sevegment indicators Stay among the most popular items to display digital information.

This contributes to the following their qualities.

• Low price. In the means of display, there is nothing more than LED digital indicators.
• Variety of sizes. The smallest and largest indicators are LED. I know the LED indicators with a number of numbers from 2.5 mm, up to 32 cm.
• Glow in the dark. In some applications, this property is almost decisive.
• Have different colors of the glow. There are even two-color.
• Sufficient small control currents. Modern LED indicators can be connected to the conclusions of microcontrollers without additional keys.
• Allow rigid operating conditions (temperature range, high humidity, vibration, aggressive media, etc.). For this quality, LED indicators have no equal among other types of display elements.
• Unlimited service life.

Types of LED indicators.

The seven-segment LED indicator displays a symbol using seven LEDs - Figure Segments. The eighth LED illuminates a decimal point. So in the seventh indicator of 8 segments.

Segments are marked with Latin letters from "A" to "H".

Anodes or cathodes of each LED are combined in the indicator and form a shared wire. Therefore, there are indicators with a common anode and a common cathode.

LED indicator with a common anode.

LED indicator with shared cathode.

Static control of the LED indicator.

Connect the LED indicators to the microcontroller are necessary through resistors that limit the current.

The calculation of the resistors is the same as for individual LEDs.

R \u003d (U power - U segment) / I segment

For this scheme: I segment \u003d (5 - 1.5) / 1000 \u003d 3.5 mA

Modern LED indicators are bright enough already at a current of 1 mA. For a circuit with a common anode, segments will appear on the control outputs of which the microcontroller will form a low level.

In the circuit of connecting the indicator with a shared cathode, the polarity of the power and control signals changes.

A segment will light up, on the control output of which will be formed high level (5 V).

Multiplexed LED control mode (LED) indicators.

To connect each seven indicator to the microcontroller requires eight conclusions. If indicators (discharges) 3 - 4, then the task becomes practically not performed. Just not enough conclusions of the microcontroller. In this case, the indicators can be connected in a multiplexed mode, in the dynamic display mode.

The conclusions of the segments of each indicator are combined. The LED matrix is \u200b\u200bobtained connected between the conclusions of the segments and the shared outputs of the indicators. Here is a multiplexed control circuit of a three bit indicator with a common anode.

To connect three indicators, 11 conclusions were required, and not 24, as with static control mode.

With dynamic indication, only one digit is lit at each time. The total output of one of the discharges is given a high-level signal (5 V), and signals come to the conclusions of the segments low level For those segments, which should shine in this discharge. Through a certain time The next discharge is ignited. Its general conclusion is given a high level, and on the conclusions of the segments of the status signals for this discharge. And so for all discharges in an infinite cycle. The cycle time is called indicator regeneration times. If the regeneration time is quite small, then the human eye will not notice the switching of discharges. It will seem that all discharges are glowing constantly. To eliminate the flicker of indicators, it is believed that the frequency of the regeneration cycle should be at least 70 Hz. I try to use at least 100 Hz.

The diagram of the dynamic indication for LEDs with a common cathode looks like this.

The polarity of all signals changes. Now the total active discharge wire is given a low level, and the segments that should be glowed - a high level.

Calculation of the elements of the dynamic indication of LED (LED) indicators.

The calculation is somewhat more complicated than for static regime. During the calculation, it is necessary to determine:

• middle segments;
• pulsed segment current;
• resistance of segment resistors;
• pulsed current general conclusions discharges.

Because The indicator discharges are shined in turn, the brightness of the glow determines the average current. We must choose it based on the parameters of the indicator and the required brightness. The average current will determine the brightness of the indicator glow at the level corresponding to the static control with the same direct current.

Select the average current segment 1 mA.

Now we calculate the pulse segment current. To ensure the required average current, the pulse current must be in n times more. Where n is the number of indicator discharges.

I segme. imp. \u003d I segme. Average. * N.

For our scheme I segme. imp. \u003d 1 * 3 \u003d 3 mA.

We calculate the resistance of the resistors that limit the current.

R \u003d (U power - U segment) / I segme. imp.

R \u003d (5 - 1.5) / 0.003 \u003d 1166 ohms

Determine the impulse currents of the general conversion convements. At the same time, there are 8 segments, then it is necessary to multiply a pulsed current of one segment to 8.

I defrost imp. \u003d I segme. imp. * eight

For our scheme I discharge imp. \u003d 3 * 8 \u003d 24 mA.

• resistance to resistors Choose 1.1 kΩ;
• the conclusions of the microcontroller control of the segments should provide a current of at least 3 mA;
• the conclusions of the indicator discharge microcontroller must provide a current of at least 24 mA.

At such values \u200b\u200bof currents, the indicator can be connected directly to the outputs of the Arduino board, without using additional keys. For bright indicators, such currents are quite enough.

Schemes with additional keys.

If the indicators require a larger current, then it is necessary to use additional keys, especially for the signal selection signals. The total discharge current is 8 times more than the current one segment.

Connection diagram of the LED indicator with a common anode in multiplexed mode with transistor discharge selection keys.

To select a discharge in this scheme, you must form a low level signal. The appropriate key will open and apply the power to the discharge of the indicator.

Diagram of connecting the LED indicator with a shared cathode in multiplexed mode with transistor discharge selection keys.

To select a discharge in this scheme, you must form a high level signal. The appropriate key will open and closes the general conclusion of the discharge to land.

There may be schemes in which you need to use transistor keys and for segments, and for general discharge convements. Such schemes are easily synthesized from the two previous ones. All shown circuits are used when powering the indicator with a microcontroller power supply.

Keys for increased voltage indicators.

There are indicators of large sizes in which each segment consists of several LEDs connected in series. To power such indicators, a voltage source is required to be larger than 5 V. keys must ensure switching increased voltage with control from the signals of the microcontroller levels (usually 5 V).

The key diagram closing the indicator signals to the Earth remains unchanged. And the power keys should be built on another scheme, for example, such.

In this scheme, the active discharge is selected high levels control signal.

There should be all segments between switching discharges of the indicator discharges for a short time (1-5 μs). This time is necessary to complete key switching processes.

Constructively, discharge convements can be combined as in one case of a multi-digit indicator, and a multi-digit indicator from individual disposable can be collected. Moreover, you can assemble the indicator from individual LEDs combined into segments. So usually come when it is necessary to assemble the indicator of very large sizes. All the above schemes will be valid for such options.

In the next lesson, connect the seven LED indicator to the Arduino board, we will write a library to manage it.

For the second year, I reanimate the amplifier of Solntsev, collected 20 years ago. One of the amplifier nodes is the output power indicator. At the time of creation, the amplifier included an indicator collected on K155L3 - 8 buildings + body kit. He worked well, but now it is not modern. Reincarnation on a modern base under the cut.
In the resuscitation process, I decided to build a new indicator, on a modern elementary database. Popular B. this moment is the indicator circuit on LM3915.


Unfortunately, immediately in our territories did not find on sale a line of LED indicators in one case and assembled on separate LEDs.

In general, it turned out well, but blurring (even turbidity) light spots did not quite suit.
In search lED ribbon Racked on the line of LED indicators in one case on 12 segments, 8 of which are green and 4 red.


In my design, 10 LEDs are used to indicate the output power of the amplifier, and two LEDs to indicate the appearance of a negative or positive voltage at the output of the amplifier.
Waiting for the parcel, the symbolic fee for the delivery and remake of the indicator did not hold from the purchase.
The findings of each indicator were carefully protected by the seller and packed in an envelope with a poupe.

The front side of each panel is closed by a protective sticker.

On the inside, the indicators are filled with a transparent compound

In general, it was even very pleasantly surprised by the quality of the indicators - not a faceless product.
The sizes declared by the seller, exactly coincide with reality. At the length of the conclusions, the manufacturer did not save.
Since the seller does not indicate the current consumption of LEDs, nor the operating voltage, then found these data with generally accepted, approximately 2 - 3 volts, at a current of 20-30 mA.
However, it previously verified the indicator LED tester T4.

UF, V - voltage at which the LED begins to glow in volts,
C, PF - Transition Capacity in Picofarades
In the Table of LEDs 1 to 8 - green, 9-12 - red.
Some variation of parameters is present, but at work, it does not affect.
Until then, the indicators came, thought not to engage in the collection of new fees, and use the layout, but it turned out that the step between the conclusions is not 2.54 mm, but even 2. It is actually visible from the drawings on the seller page, but on such trifles when buying Attention did not pay.
By installing the metric grid in Sprint-Layout, spread the board. In the process, it was still faced with one if not difficulty, then not the standard of the panel - the findings of the LEDs are not located in the center of the case, but shifted to one edge - are located 1.6 mm from the center. It created a slight inconvenience - I needed two indicators nearby, without a gap between the housings. It was necessary to reduce the grid step to 0.25 mm and print a board on paper several times, trying on the indicators.
As a result, it turned out such a fee

Comparison of results:

Installation in the scheme and testing

The camera is a little soap the glow of the segments, but everything looks very good. Each LED creates its clearly defined glow, without creating a cotton spot.
Perhaps this is a subjective feeling, but the indicator came to life, the rate of indication increased and became more adequate compared to the initial option - some inhibition disappeared.
By buying, the resulting result, despite the non-standard pitch of the conclusions and their displacement relative to the center of the housing, is extremely pleased and I can recommend this product.
In addition, the seller has various indicators in a wide range and for different purposes.
Place in the sprint:

In the first tab - a board with chips + indicator board on separate LEDs. The second tab is a board for observed indicators.