I’m selecting a level shifter for the APA-102 leds. I know that most people successfully (including me) connected it directly to a 3.3V data pin without shifter. However since I’m designing a PCB it might be smart to keep the official specs in account (Adafruit mentions this also with their Dotstar LEDs).
I know the octal shift registers that work like the SN74HCT245 that is used on the FadeCandy board. However I only need one channel (no more ports available at the RFDuino and APA is fast).
Does anyone have experience with this single channel buffer chip from TI: SN74AHCT1G125 ?
(I know it’s an Adafruit doc, but the level shifter I buy is from Sparkfun: https://www.sparkfun.com/products/12009 - they have the full Eagle files - so you could easily pick out the single channel you need).
That said, I believe the “HCT” is the part of the identifier to look for in order to get “fast enough” so what you’re looking at should be good, @Kasper_Kamperman - that said, again, remember you need 2 for the APA102.
@Mike_Thornbury Doesn’t work for the purpose of shifting the Teensy’s 3.3V output to 5V as input for WS2812B LEDs. If you search on the Sparkfun part number here you should find my longer explanation of what went wrong.
As with running without a level shifter at all, there are plenty of situations where that may work, but may be some situations where they don’t. The 74HCT’s that multiple of us here are recommending are the only solution that hasn’t had any “doesn’t work” situations.
We are using a 74HCT2G17GW-Q100 to shift from 3.0V to 5.0V for APA102. Our software runs on a dsPIC device. There might be a bug in the software but it seems more like a hardware issue with the selected 74HCT. We will probably test the suggested sn74hct125d. If it works I’ll come back and report.
And by the way: we used the sparkfun level shifter too in another project and it didn’t work either. Worked with another 74HCT though.