Hello
For certain boards without an USB port and needs to be powered via a regulated voltage, what is the best way to power such board? In another word, how do I get a regulated 5V or 3V voltage to a pin? Is it possible to cut open the USB wire that is plugged into a power source (say, laptop) and isolate the V+ and GND cable and use then solder a male pin to it so that it can be plugged into a breadboard?
For a typical 5V Arduino, apply regulated 5V to the pin labeled "5V".
Similarly for a 3.3V Arduino (this won't work with a 5V Arduino that has a 3.3V output pin, like the Uno R3).
There are all kinds of power supplies and yes, you can use a USB "charger" and cut the cable if you don't want to plug it in with a regular USB cable.
I've got an Arduino Uno in a car project and the 12V car power goes into the barrel jack.
Isn't USB regulated voltage?
I thought in the Arduino, the USB port assumes regulated voltage and therefore power from the USB does not go through the voltage regulator.
I guess I just want to know if it's safe to assume USB power is regulated at 5V, and therefore can be used for applications that calls for regulated 5V, such as the 5V pin on the Arduino Uno. In other word, if I connect the power cable from a USB cable directly to the 5V pin on the Arduino, without using the USB port on the Arduino, is that safe to do?
Thanks
slightly more detail than you asked for:
barrel connector >> 5V regulator >> tie point to USB and V IN. the 5 V regulator is limited in current capacity, and if you power everything from the 5V pins you treat your Arduino as a fuse.
get a male header strip, saw it to the length of the female header strip, and power the microcontroller by a regulated external power supply. add a Keyestudio I2C Shield V1 to proliferate 5VDC, ground, and I2C:
do the same with modules. make a permanent wiring harness. have the ability to replace anything in seconds. a benefit of connecting this way is, you wire it once get it working, and you never knock a pin out of a socket. when it's 100 percent, hot glue all wires soldered to pins and no worries about shorts or yanked wires
Sort of.
For version 1 of USB the spec says 5V +/- 5%, 4.75V to 5.25V.
For USB 2.0 the spec says the voltage supplied by high-powered hub ports is 4.75 V to 5.50 V.
power from the USB does not go through the voltage regulator.
Correct. In some Arduino designs USB 5V goes through other components, and the voltage on the MCU (and the "5V" pin) can be as low as 4.5V.
The typical USB cable has red insulation on the +5V wire and black insulation on the Ground wire, but it's best to check with a meter. The data wires are usually green and white.
thanks. I noticed there are power supplies that can produce 5V DC output and they are pretty cheap. I did have more trouble finding 3V DC power supplies from reputable sources.
What is the easiest way to go from 5V to 3V DC? Linear voltage regulators? Any other methods that are popularly used to step down a DC voltage?
Thanks
You do not state what your actual power source is. For example from the wall outlet at 110 or 240v you can just use a Standard phone charger (depending on your arduino, and phone). If battery powered you can use buck converters, boost bucks, boosts, dc-dc, linear regulators, voltage dividers etc etc and the most appropriate will probably depend on your power source and requirements
I like AMS1117 for it
For what...
Current matters.
Big-board Arduinos like the Uno and Mega have a dedicated 3volt/150mA regulator onboard.
Leo..
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