I am building a robot that runs only when a matching RFID tag is identified..for that I need a motor driver shield for running the motors and a RFID module. The problem is if I attach the motor driver shield directly to Arduino (MEGA) there won't be any 3.3v left which is necessary to power the RFID, so what I am thinking is connecting all the pins of Arduino and shield separately using jumper wires and leaving the 6 power sockets unconnected. If I connect a 9v battery to Arduino mega to power the RFID and micro-controller itself, what battery should be connected to the shield? Is it necessary to connect the GND of Arduino awa shield even if the power sources are separate? Is it necessary to attach 2 switches for each source?
Glorfindel
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You should check the schematics for your motor shield to see what pins are actually used. Just because a pin exists doesn't mean it is connected to anything. You may well find the 3.3V pin isn't actually used by the shield.Majenko– Majenko2020年11月05日 11:17:05 +00:00Commented Nov 5, 2020 at 11:17
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Why not just use a Buck converter on one of the 5V power lines and reduce the voltage to 3.3V.Jeff Wahaus– Jeff Wahaus2025年08月25日 16:04:42 +00:00Commented Aug 25 at 16:04