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Sorry if this is a dumb question, I'm new to Arduinos. I'm planning to use a MOVI voice shield with SparkFun's RedBoard Turbo (3.3v). The RedBoard Turbo requires a power supply under 6VDC, but the MOVI website recommends a power supply of 9VDC to the Arduino, because the MOVI can't have its own power supply. Will this destroy my RedBoard? Or is this safe and just something you have to do when using shields? Thank you.

The product website says: "A 7V to 16V 500mA external power supply that powers MOVI™ through the Arduino board. The power consumption of both boards is just above what the USB port can provide. If you don't have already one, this 9V adapter from Adafruit will work perfectly."

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Although I have not used either SparkFun's RedBoard Turbo or the MOVI voice shield, reading the specifications, which you can find on their respective web sites, it would appear that they have incompatible power requirements. The SparkFun's RedBoard Turbo board web page says

The barrel jack connection on the RedBoard Turbo has a lower input voltage than most Arduino development boards. Make sure that you are using a power supply below 6V. Please be aware that the RedBoard Turbo is also a 3.3V device and not a 5V one like the original RedBoard.

Whilst the MOVI voice shield PDF manual (page 7) says

What you don’t see in Figure 1 is a power supply jack. MOVI is powered through the Arduino board that needs to be powered using an external power supply. The external power supply should provide between 7V and 16V and at least 500mA current. During tests we usually used either 9V or 12V. Battery packs with this specification work as well.

So the one needs less than 6V whilst the other more than 7V. I don't know if you can break the power connection between the two boards and feed the MOVI from a separate supply (9V is very common in the Arduino world) or you may have to swap your SparkFun for an Arduino that runs on 5V and uses a 9V supply.

The gotcha is that Arduino boards, their clones and code compatible boards such as the ESP32 etc fall into 2 different groups, those that run on 3.3V and those that use 5V, and you must be very careful you don't over voltage the latter.

I haven't delved into the specifications further, but you will almost certainly find that the logic levels used by the two boards are also incompatible. One will be using 0 & 5V whilst the other 0 & 3.3V. Connecting a 5V logic output to a 3.3V logic input is not conducive to long life and happiness for the latter.

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  • you understand it wrong. the answer is wrong. the shield takes 5 V from the 5 V pin of the board and the regulator on the board can provide it. the Uno has a different regulator and needs a different input voltage but provides same 5 V on 5 V pin. problem is if the external power supply can provide the necessary current and that doesn't depend on voltage – Juraj May 19 '19 at 6:08
  • @Jraj If you compare the schematic of the original RedBoard cdn.sparkfun.com/datasheets/Dev/Arduino/Boards/RedBoard-V22.pdf with that of the Turbo cdn.sparkfun.com/assets/6/5/4/5/0/RedBoard_Turbo.pdf There is no 5V regulator on the Turbo board, all it does is pass the 5V from the USB straight across to the 5V socket on the edge connector. There doesn't appear to be any connection between that and the rest of the board. This query is about powering via the barrel connector. The original board does have a 5V regulator and it is connected to the edge socket. – Peter Jennings May 19 '19 at 12:50
  • @Juraj Sorry, typo – Peter Jennings May 19 '19 at 13:40
  • @Juraj The MOVI manual clearly states that it takes its power from the Arduino and that it should be between 7V and 16V not 5V and Please note: MOVI cannot be powered through a USB power supply or the USB cable of​ ​the​ ​Arduino​ ​board​ ​as​ ​the​ ​voltage​ ​provided​ ​is​ ​less​ ​than​ ​6V. So if the input supply to the RedBoard Turbo (<=6V) was passed to the MOVI it would not work. – Peter Jennings May 19 '19 at 14:05
  • does the shield have a power regulator and takes the power from Vin? I don't believe it. – Juraj May 19 '19 at 14:30

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