SparkFun RedBoard Qwiic - Pre Sales Questions

Qwiic System
1

Hello,

I would like to verify a few things about the SparkFun RedBoard Qwiic :

  1. You cut the jumper to 5V and solder a blob to 3.3V and now the board runs at a 3.3V logic level?

  2. Once setup for 3.3V, I can still use a 12V wall wart to power the device?

  3. At 3.3V does the board still run at 16MHz or it is running slower (I see other 3.3V boards running at 8MHz)?

Thanks

2
  • - That is correct as mentioned in the [[hookup guide](https://learn.sparkfun.com/tutorials/redboard-qwiic-hookup-guide#hardware-overview) (click the **Jumpers** button), that jumper controls the voltage to the VCC pin of the ATmega328.
  • Just be aware if you are using a shield that uses the I/O Ref pin, that it is still tied to 5V. It was accidentally carried over from the previous design of the original RedBoard instead of being tied to that jumper selection.
  • - That is also correct, as shown in the [[schematic](https://cdn.sparkfun.com/assets/c/5/7/e/f/RedBoard-Qwiic.pdf) the 3.3V regulator (AP2112) takes 5V from the 5V regulator (LM117). As mentioned in the [[hookup guide](https://learn.sparkfun.com/tutorials/redboard-qwiic-hookup-guide#hardware-overview) (click the **Power/Reset** button), the LM117 can take 12 volts.
  • - I am pretty sure that crystals run at their resonant frequency once powered, so it should still run at 16MHz.
    • ](https://learn.sparkfun.com/tutorials/redboard-qwiic-hookup-guide#hardware-overview)](https://cdn.sparkfun.com/assets/c/5/7/e/f/RedBoard-Qwiic.pdf)](https://learn.sparkfun.com/tutorials/redboard-qwiic-hookup-guide#hardware-overview)
    3

    Thanks for the quick reply…that gives me the info I need.