Hello,
I've been going in circles trying to figure this out and it's just gotten more confusing. I'm trying to figure out how to power the Nano 33 IoT and an LED strip via a buck converter from a LiPo battery.
Here's the setup:
- 10s LiPo battery (42V max, 30V min voltage)
- Pololu D36V28F5 5V, 3.2A Step-Down Voltage Regulator - accepts 50V max, outputs steady 5V (3.2A max)
- Nano 33 Iot
- Individually addressable APA102 LED strip, only 7 pixels (less than 1A), takes 5V input
- Both the Nano and the LED strip take power and ground directly from the pololu converter's output (that was the main intended advantage of this setup). LED strip gets SPI clock and data from the Nano hardware clock and data pins (11, 13).
Here's the behavior I'm seeing:
Test 1: When powering both the Nano 33 IoT (via the main micro usb port) and the LED strip (power from the Nano's VIN, ground from Nano's ground) from a laptop's usb port, everything works as expected. Running an example script (moving rainbow) works perfect.
Test 2: When powering both the Nano 33 IoT (via the main micro usb port) and the LED strip (power from the Nano's 5V out, ground from Nano's ground) from a laptop's usb port, no LEDs on the strip light up at all. Nano's onboard lights work fine.
Test 3: When powering the Nano 33 IoT (via the main micro usb port) from a laptop's usb port, and the LED strip from the power regulator, no LEDs on the strip light up at all. Nano's onboard lights work fine.
Test 4: When powering both the Nano 33 IoT (via the VIN pin) and the LED strip from the power converter, I get a jumpy, frozen rainbow. Touching almost any wire can affect the lighting behavior. I assumed it was a grounding issue, but.. everything is grounded to everything else. The Nano and the LED strip share a ground - that's usually the problem.
Test 5: When powering both the Nano 33 IoT (input into the 5V out pin) and the LED strip from the power converter, no lights at all.
Test 6:When powering both the Nano 33 IoT (via the micro usb port) and the LED strip from the power converter, I get a frozen LED strip rainbow, no updates/movement. Nano's onboard lights work fine.
Test 7: When powering the Nano 33 IoT (input into the 3V3 out pin) and the LED strip from the power converter, everything works perfectly! But this seems like a terrible idea. I'm surprised it hasn't damaged something already.
Using a multimeter, the output at the power converter leads (that plug into the breadboard with the Nano) is a steady 5.1V.
Its possible this is entirely an issue with the SPI clock and data signals to the LED strip, but I don't know why that is, or why the power source affects it.
Any help would be much appreciated!
Thanks