Using the NANO 33 with DFPlayer Mini

Using Arduino Project Guidance
1

I've been prototyping a project utilizing a DFPlayer Mini MP3 breakout board with an Arduino UNO R3. This required a voltage divider on the RX pin into the DFPlayer to bring 5V signals down to 3.3V. This works great.

For my final build, however, I'm looking to replace the UNO with an Arduino NANO 33 BLE SENSE. Specs on this board say that the operating voltage for the board is 3.3V. I'll be powering both the MC and the breakout from an external 5V source, and I want to confirm that the TX pin on the MC will still only deliver 3.3V and thus no voltage divider should be necessary for the RX on the DFPlayer. Is that correct? Or would a divider still be a good idea "just in case"?

TIA!

2

If the controller voltages are 3.3 why do You intend to power them using 5 volt and not 3.3? Power them using 3.3 volt.

3

Railroader:
If the controller voltages are 3.3 why do You intend to power them using 5 volt and not 3.3? Power them using 3.3 volt.

Several reasons:

  1. the VIN on the NANO 33 is 5-21V (even though the "operating voltage" is 3V3).
  2. the VCC on the DFPlayer is 5V tolerant, just the data pins are not (community says it actually works better when powered by 5V rather than 3.3V).
  3. I'm using other 5V components (neopixel strips, and servos), so having one 5V rail is very convenient and since both the MC and the DFPlayer are 5V tolerant on the power it just makes sense to stick with the 5V.
4

cstein:
Several reasons:

  1. the VIN on the NANO 33 is 5-21V (even though the "operating voltage" is 3V3).
  2. the VCC on the DFPlayer is 5V tolerant, just the data pins are not (community says it actually works better when powered by 5V rather than 3.3V).
  3. I'm using other 5V components (neopixel strips, and servos), so having one 5V rail is very convenient and since both the MC and the DFPlayer are 5V tolerant on the power it just makes sense to stick with the 5V.

Thanks for the update! Just be careful about the current used from the 3.3 volt pin when "mains" is 5.0 volt.

5

Railroader:
Thanks for the update! Just be careful about the current used from the 3.3 volt pin when "mains" is 5.0 volt.

I guess that's the crux of my question, even though perhaps I didn't explain it well.

I'm feeding each board 5V. Each board states that the data pins/operating voltage are 3.3V. What are the chances of the data pins errantly putting out 5V? Should I leave the voltage divider in place as a precaution? Or how else can I "be careful about the current"?

6

If the boards are rated to run from 5 volt, fed at the proper pin, You don't need to fear any danger.
Voltage dividing as a precausion will not work. Don't do it. Watch the voltage of the I/O pins and design according to that.

I try to explain. You feed the board with 5 volt. On the board there is a converter producing 3.3 volt. That means that 1.7 volt is "lost" on the way. If the converter is a cheap analog converter there will be some heat built up. The loss of power converted to heating is 1.7 times the current (In Amps ). Depending on the cooling of the converter the capability of handling Watts of heating varies.
Check the specifications carefully, what current that 3.3 volt pin can deliver regarding surrounding temperature, cooling etc.