## How to calculate controller qty for spi signal strips

As the stability  improvement of spi signal led strip,
the spi signal strips are widespread use in the holiday decoration lighting and poplar among people.
Such as the APA102 super led strips,and ws2801 digital rgb,and also ws2812b once was popular among people,for the color programmable controlled the color dimming,and lower cost than DMX led strips.

### First step to calculate the LED pixels

The ICs for spi signal leds normally have 3 channels,such as apa102,apa102,ws2812b,sk6812,ws2801,ws2811,lpd6803 and so on,they are 3 channels IC.
It means one of these IC can control three color chips,such one R(red),one G(green),one B(blue) total three color dimming,
these three chips combine as tens of thousands of different colors,so in this case one three-channel IC is one pixel,
so the pixel quantity is equal to the IC quantity.
But sometime you may ask when one IC control 3 RGB leds,how to many pixels in this case?
For these 3 leds are controlled by the same IC,the 3 leds is a group, the R(red) channel of the three RGB LEDs in the group are series connection using the same R(red) channel of the IC.
The G(green) and B(blue) is work in the same way,so these 3leds is just one pixels.
Also the one three channels IC control 6leds work the same way as above ,so it is also one IC is one pixel.
But also have some different ICs is not 3channels,such as LPD8806 with 6 channel,and UCS2912/9812 has 12 channels.
but also the control in the same way.when controlling RGB led is three channels combine a pixel,so one LPD8806 IC has two RGB pixels,one UCS2912 IC or UCS9812 IC can control 4 RGB pixels.
But the UCS2912 or UCS9812 addressable rgbw is special circumstances,
for one RGBW SMD LEDs has one R(red),one G(green),one B(blue),one W (white) four color chips,in this is case is 4 channels combine a pxiels,
So one UCS2912 or UCS9812 IC control 3 RGBW pixels,

### Second step is choose controller depend the pixel qty.

For T-1000 controller can control 2048 RGB pixel,so it is 2048 three-channel ICs.
But for T-4000,and T-8000,and other ST4K and so on,these controllers have many ports (4 or 8 ports,even other quantity of ports),
And each port control some pixels,such as 1024,or 512 pixels each port.
So in this step you need to have the initial installation plan about the strips,and calculate each port`s controlling pixel qty,then transform into the how many meters each port control.
especial for the led matrix panel display,for the display can not be cut,sometime you just can not depend on the pixel,but you should know the entirety pcs.

### Supplementary Condition:

One,for the spi signal led strips,there is limited in the distance from the controller to the first IC of the strips,also the distance between the distance of the before and after the two ICs,
Normally it is better not the cables from controller to the first IC of the strips is not longer than 10m,and the cables from before and after the two ICs is also not further 10 meters too.
If it is further than 10m,we should add the signal enhancers (one type of amplifiers to magnify the distance of signal,
There is one is signal input,and the other is signal output  work together as a pairs.
the signal input on the side of single input, signal output is on the side of  signal come out.
Two,most the full color strips are low voltage direct current such as DC5V,DC12V,DC24V,
So it is better to add extra power to the strips every 5m so as to reduce the voltage drop.
and when the strip with waterproof connectors normally will also demand the the DC connctors so as for the connect to extra power cable.