Could this be caused by exceeding Qwiic bus max power capacity?

Sensors
1

Hello.

I have a Qwiic bus powered by an Thing Plus - ESP32 WROOM (WRL-20168).

Attached to this bus are:

  1. Four (yes, four) Alphanumeric Displays (COM-16916)
  2. Indoor Air Quality Combo Sensor (SEN-25200)
  3. Ambient Light Sensor (SEN-15436)
  4. Environmental Combo Breakout (SEN-22858)

All sensors connected via short, 50mm connectors.

Everything works fine until I display text in all four displays. Seconds later, all displays turn off, and I can see the leds on all of the sensors dimm a little bit, and the SEN-25200 starts returning NAN values. After that, displays become unresponsive (they won’t turn on any segments). If I reset the ESP32 board, everything goes back to normal. I can even show text in one, two or three displays, but as soon as I turn on the fourth, all goes dark again.

Is it possible that I might be draining too much power from the bus? And if so, what would be the solution to this?

Thank you!

2

I think yes. Sounds like your power supply is not sufficient for all components.

3

Yep - that board can provide ~600mA of power to peripheral devices, that setup likely exceeds that amount (you can confirm by testing with fewer items hooked up at once)

You can either implement sleep modes for certain devices with interrupts to keep the power overhead at any given time constrained to say maybe 1 or 2 at a time, or get a few more MCUs and split them up that way, or snip the power and ground wires on the i2c/qwiic bus and supply power from another 3.3v source to each

4

Thank you Russell. Much appreciated.

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