Voltage Level Shifting for APA102/SK9822 ! I use an RPI for most of my large LED Installations, and have always used a NULL pixel very close to the RPI as the voltage level shifter. However this has its limitations. I could never get anything higher than 10-12Mhz with a 2 meter cable. Last night I tried using a LS74HC08 (https://www.nxp.com/documents/data_sheet/74HC_HCT08.pdf a simple cheap Quad AND gate). I tied 2 inputs of 2 gates together. One gate drove the CLK and the other drove the DATA lines. I have the IC connected to the “+5V” & “GND” of the Rpi. Was able to drive a 300 pixel panel that I made with a 1.5m cable(CAT5 with data and clock wrapped in GND) at 15-20mhz !!! This could be used to drive WS2812(although its overkill) on any 3.3v micro controller as well!
Cool, thanks for sharing! I need to find a THT level shifter smaller than the SN74HCT245N I’m currently using.
Nice to have options, and glad to hear you got good speed.
I agree @Jason_Coon .
Thanks for the information, has anyone done a comparison between TTL and CMOS versions of the various level shifters?
Level shifter tests
http://happyinmotion.com/?p=1247
Newark Electronics Tips & Tricks
http://www.newark.com/pdfs/techarticles/microchip/3_3vto5vAnalogTipsnTricksBrchr.pdf
@Justin_Onimus Thanks Justin your blog post is great, I have studied it in depth previously, but its only useful for Neopixels. The document you posted is excellent thank you!