All,
I have read through what I can find on this topic.
I am only getting 3.3V from the 5V pin when powered by external 12V power source using the VIN pin. If I plug in to the computer, the 5V pin supplies 5V. Rough wiring diagram below. All voltages are what they should be except for the 5V out.
What made me find this is that my program will not run without being plugged into the computer.
Which one of the hundred types of Arduino are you using?
Are the Hall sensors the only things connected to the mystery Arduino 5V?
Please post a complete schematic. Hand drawn, photographed and posted is fine. Include all pin names/numbers, components, their part numbers and/or values and power supplies.
A 24V to 12V buck converter may cause the Arduino voltage regulator to overheat and shut down, partially or completely.
Instead, use either a 7 to 9V buck converter connected to Vin, or a 5V buck converter connected to the 5V pin.
I am use the Arduino Mega Rev 3. It is a brand new board bought for this project.
Okay, please supplement that information with the information requested in reply #3, and answer also the question that was asked there.
Here is the diagram, sorry for poor drawing.
Only the two Hall sensors are connect to the 5V pins on the board. I am driving the motor straight from the 24V supply.
The hall sensors are two ky-003 sensors rated for 5v supply.
Power supply is a IDEC ps5r-sd24.
Buck is a EA120-12V
Why would this be the case? I have measured to output to 12.18V, which is within the allowable range.
...for a board that is not supplying power to anything else, yes.
The on board 5V regulator is not heat sinked so will supply limited current before it overheats and shuts down. The amount of current depends on the voltage input to Vin or the power jack. The higher the voltage the less current can by supplied. To output 5V from a 12V input the regulator must drop 7V. The maximum power dissipation for the (not heat sinked) regulator is about 1W. So that means that the maximum current is about 142mA [1W / (12V-5V)]. The Mega takes around 50mA that leaves 90mA (at best) for the rest. That is why it is not recommended to use 12V input to Vin. It is much better to drop the higher voltage to 5V and apply that 5V to the 5V pin of the Arduino, bypassing the weak 5V regulator.
To close this, I ordered a 24v to 5v buck and swapped it with the 24v to 12v. I plugged the lead into the 5V pin and everything is working as it should now.
Thank you everyone for your assistance!
What lead?
The positive 5V lead from the buck converter.
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