Anyone mind looking over my schematic and seeing if I’ve set things up correctly?

[Apa102]

Anyone mind doing a quick look over my schematic

Basically showing a teensy 4.1 thats connected to a computer through a micro usb, thats feeding SPI (data and clock signals) to a level shifter (3.3v to 5v) which sends those translated signals to my RGBLED’s. The led’s need 5 volts, and the teensy is only capable of 3.3 volts so an external power supply is powering the led’s.

I mostly just need to know if the grounds are in the right place, particularly the ones connected to the microcontroller.

 

[JarkkoL]

Hmh, why are you upping the control voltage to 5V? Isn't it only the VCC of the LEDs that needs to be 5V while the control signals should be 3.3V?

 

[Apa102]

Hmh, why are you upping the control voltage to 5V? Isn't it only the VCC of the LEDs that needs to be 5V while the control signals should be 3.3V?

What I understand is this:

For a "high" signal on the data or clock line, you need at least 70% of the supply voltage (page 3, VIH).
If the supply voltage is say 5.2V, dropped to e.g. 4.9V due to cable resistance and high current draw of the LEDs, this would be 3.43V; The 3.3V of the Teensy would be too low in this case.
To be on the safe side, you would need to lower the supply voltage to 4.7V or lower.
Having said this, I think many APA102 do work without a level shifter, because apparently the 70% seems to be lower in practice.

Apa102 data sheet: https://cdn-shop.adafruit.com/product-files/2477/APA102C-iPixelLED.pdf

 

[JarkkoL]

Yeah, here's HW hookup in Sparkfun: https://learn.sparkfun.com/tutorials/apa102-addressable-led-hookup-guide/all#hardware-hookup

 

[KenHahn]

Your wiring looks OK. Depending on how many LEDs you are driving, stay mindful of the 5V power draw especially if you are using a solderless breadboard.