Directory of RSS feeds

RSS feeds in the directory: 374

Added today: 0

Added yesterday: 0

Hi-Tech / Hardware

Make a "mood watch". Part one. Indicators 23.01.2020 at 08:15

There is a Supertrend radio lamp Alex services Michigan http: on a piece of sewer pipe bonded flexible matrix of addressable LEDs, top cover with Leroy Merlin and all of this is connected to ESP8266. The thing is simple, inexpensive, very entertaining ... and pretty useless from the point of view of everyday life.

Decided to find a more practical application for the address of the diodes, such as in electronic watches. We call the project — "mood watch".

the Idea is to make the clock on the WS2812 I have already raised here, and here. In addition, there is experience in the use of weather stations with a matrix display. Considering all the disadvantages of operation it is possible to estimate requirements for the indicator is:

Ergonomics. That is, should be on segments rather than individual points, the numbers should be tilted 10 degrees, as in all the seven-segment displays. Everything should be aimed at maximum readability at the expense of universality. The simplicity of the scheme and the minimum budget indicator. Easy to connect to various microcontrollers. High scalability. Indicators can be of almost any size.

To diversity has made his project led SK6812

LEDs SK6812

I've done reviews of WS2812B addressable LEDs from WorldSemi. Not so long ago on the market there is an alternative — SK6812 from Opsco Optoelectronics.

SK6812 different from WS2812B smaller chip size, a large variety of housings, as well as a few other timings that do not prevent them to be fully compatible and functional copies. Also SL6812 has a switching frequency of 1.1 KHz vs 409Gts WS2812.

Line of LEDs SK6812 also consists of WRGB LEDs, which have a white chip.

the Diodes for the indicators I ordered on Taobao in the housing of the 3528. The seller, who calls himself the Shenzhen Guangyihong Electronics, says proudly on its own. At Opsco Optoelectronics such a case is called SK6812MINI-E. On Aliexpress such case I have seen, but it is possible to replace them from the more popular SK6812-MINI and WS2816B-MINI size 3535

200 pieces SK6812 cost me $9.02 with free shipping by China and the parcel weight is almost not added. It turned out almost twofold cheaper than buying on Aliexpress

the Comparison in the case WS2812 5050 and 3528 SK6812

Datasheet on SK6812 is on the site of the Chip and Dipa

Charge indicator

the Board was developed so as to fit into minimum order JLCPCB for $2

Indicators are turned with a height of 70 mm or about 2.8". One plate got two numbers and one separator. Each segment consists of 3 address of the diodes and two capacitors. The comma and the colon two diodes.

This order JLCPCB costs about 500 rubles per 5 plates (including shipping)

it is a Pity that I saved on the solder stencil. Had to stock up on a toothpick and patience to solder paste

and the capacitors are 0.1, soldered only one per segment. By the way, performance is not affected.

Connection to Arduino showed the efficiency of all indicators


Case designed to print on a 3D printer. After a series of trial and error we have the following parts:

the Body of the indicator and separator Inner insert that holds the Board and will share the segments And the diffuser of white plastic with a thickness of 0.6 mm

Tried to first do the insert of transparent plastic material, but the dispersion was very bad

the Final version of the corps indicators

Well, the final activated


Programmatically include all three colors at maximum brightness — get limit the current consumption indicator — 320mA or 15.2 mA for a single diode

The current limit for each color is the same — 112mA (5,33 one diode)

the removal of the current-voltage characteristics showed the following result:

the color of the indicator ceased to change from about 4V. After 4.9 was included In the constant current mode. That is, for maximum power/brightness of the indicator need to feed it a voltage of 4.9-5.5 (the max according to Datasheet). If the allowable decrease in brightness by 30% -can be supplied in a more economical mode of 4V

though on the Datasheet salena lower limit of 3.5 In power, 4 below.In making voltage supply is not recommended, as due to incomplete opening of the blue and green LEDs will be distorted colors.

the Heating indicator 4B — 35S

When 5V is already 46S

At 5.5 V the temperature is almost 48S

It perfectly fits to the maximum 85 degrees C according to the Datasheet. The more constantly to drive the indicator on the maximum brightness of each color is not planned.

to Summarize

overall I am completely satisfied with the result. About what effects you can program these indicators, as well as about the final product "watch in the mood" I will write in the following articles

For those who are interested in the sources of the PCBs I created an open source project on GITHUB

the Drawing of the case on TINKERCAD

The post Do "mood watch". Part one. Indicators appeared first on