But while I have you @Jason_Coon I noticed that you added some 500 Ohms resistors on your shield. Last I checked, those resistors are now folklore that was started by adafruit in their uberguide back in days when they were maybe needed on the very first neopixels.
I just bought 3 of your shields and m plan is to just bridge those contacts with solder. Any reason not to?
And did you find that the capacitors help (as in you added them after seeing issues), or you’re putting them just in case?
Thanks
@Marc_MERLIN I just put together a quick Christmas installation with an ESP8266, some SK9822s and some 12v WS2811s. I used a level shifter but forgot to add the resistors on the output. The SK9822s we’re fine but the WS2811s had terrible flickering till I added a resistor in the data line, this fixed it I did use 100ohm though
Thanks @Jeremy_Spencer , first time I see this (strips that need the resistor). Electrically, does anyone know what the resistor actually does? Doesn’t it lower the signal voltage back down somewhat, when usually the issue is that it’s not high enough to start with (unless you use a level shifter to bring it from 3.3V back up to 5V?)
The small capacitors on my shields are decoupling capacitors recommended by the 74HCT245 datasheet to reduce high frequency noise that can adversely affect the high speed level shifters.
The resistors, in addition to supposedly protecting the LED data pins from current onrush (according to Adafruit), can also be used to match the data wire impedance. I usually use around 330 Ohm resistors. You can definitely try just bridging the connection.
The OctoWS2811 adaptor uses 100 Ohm resistors to match the impedance of Cat5/6 ethernet cable.
@Jason_Coon ah, impedance, I keep forgetting about that, one of those pesky electronic reality things I assume it doesn’t matter for short wire runs (<1m) but it probably does for longer ones. Thanks for explaining (and duly noted on the capacitors, been using my level shifters without them and I guess got lucky so far)
@Lawrence_Clark yeah, you can definitely get by without a level shifter, it’ll often work just fine, until it doesn’t. Differences in power supply voltage, data wire length, etc, can make them necessary.
@Jason_Coon I read the spec sheet of the level shifter and basically they recommend a 0.1uF capacitor between Gnd and Vcc to “clean up power”. Is that correct?