linux-kernel - Re: [PATCH v3 0/3] leds: add driver for SPI driven WorldSemi WS2812B RGB LEDs

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Message-ID: <Y5g/9ETxQEVOqB5d@duo.ucw.cz>
Date:   Tue, 13 Dec 2022 10:03:48 +0100
From:   Pavel Machek <pavel@....cz>
To:     Chuanhong Guo <gch981213@...il.com>
Cc:     linux-leds@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Stanislav Jakubek <stano.jakubek@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Johan Hovold <johan+linaro@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        Sven Schwermer <sven.schwermer@...ruptive-technologies.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 0/3] leds: add driver for SPI driven WorldSemi WS2812B
 RGB LEDs

Hi!

> This patch adds support for driving a chain of WS2812B LED chips
> using SPI bus.
> 
> WorldSemi WS2812B is a individually addressable LED chip that
> can be chained together and controlled individually using a
> single wire. The chip recognize a long pulse as a bit of 1 and
> a short pulse as a bit of 0. Host sends a continuous stream
> of 24-bits color values, each LED chip takes the first 3 byte
> it receives as its color value and passes the leftover bytes to
> the next LED on the chain.
> 
> This driver simulates this protocol using SPI bus by sending
> a long pulse as 3'b110 and a short pulse as 3'b100. The SPI
> frequency needs to be 2.105MHz~2.85MHz for the timing to be
> correct and the controller needs to transfer all the bytes
> continuously.

Is this the same thing as NeoPixel? If so, that may be better-known
name.

Best regards,
								Pavel

-- 
People of Russia, stop Putin before his war on Ukraine escalates.

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