RobotDyn Mega 2560 PRO MINI 3.3V or 5V?

Hi,

I am a total newbie on Arduino, but I know I need the RobotDyn Mega 2560 PRO MINI as I need 3 hardware UARTs. The problem is that I don't understand which version I need.
They are available in a 3.3V version and a 5V version.

I will use this on an Ebike, and it will be powered by a 5V output on the bike.
At first I thought that I should get the 5V version of the board.

But looking at the specs it says:
Power In:
For 3.3V = 5~9V (peak 18V)
For 5V = 7~9V (peak 18V)

Does this mean I should get the 3.3V version as the power in is between 5-9V?

Or have I misunderstood anything?

I will either get this version:

Or this version:

Both are available in 3.3V and 5V versions.

The listed supply voltage goes to the on-board voltage regulator and must be higher than the operating voltage Vcc. The only board difference is the regulator output voltage (3.3/5V) and the resonator frequency (8/16MHz). You either connect the board directly to your battery, or use a step down converter to reduce the voltage to something acceptable by the board. If you already have a good 5V regulator, with clean and uninterrupted output voltage, you can connect it directly to the 5V pin of a 5V Arduino.

The controller voltage should match the the operating voltage of the devices connected to the UARTs.
Are you sure that you want to have a USB port?

joq3:
I will either get this version:
Mega 2560 PRO MINI, ATmega2560-16AU - RobotDyn
Or this version:
Mega 2560 PRO (Embed) CH340G/ATmega2560-16AU - RobotDyn

Both are available in 3.3V and 5V versions.

I think you should go with the second one as it has the USB on it so you can easily power it up or connect it with your PC. Their sizes are almost same so you won’t have much problem in mounting it on your bike. Power it up with 5V and it will work fine, no need of using 3.3V.

Btw these are quite amazing boards, I haven’t seen such a combination of Arduino Mega 2560 and Arduino Pro Mini before, I think it’s cool and will be handy.

joq3:
I will either get this version:
https://robotdyn.com/mega-2560-pro-mini-atmega2560-16au.html
Or this version:
https://robotdyn.com/mega-2560-pro-embed-ch340g-atmega2560-16au.html

Both are available in 3.3V and 5V versions.

I think you should go with the second one as it has the USB on it so you can easily power it up or connect it with your PC. Their sizes are almost same so you won't have much problem in mounting it on your bike. Power it up with 5V and it will work fine, no need of using 3.3V.

Btw these are quite amazing boards, I haven't seen such a combination of Arduino Mega 2560 and Arduino Pro Mini before, I think it's cool and will be handy.