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Topic: how to power arduino uno (Read 1 time) previous topic - next topic

dbutler0526

Can i power and code the arduino uno by a 5v usb cord?

mmcp42

yup - assuming the USB is connected to your PC
it's how I do it all the time! :)
there are only 10 types of people
them that understands binary
and them that doesn't

cjdelphi

The uno consumes very very little power, usb supplies 500ma i've not done the calculations but you should be able to run at least a couple hundred of them (and a few hundred more if you remove everything except the atmega chip) ..

The linear regulator is a huge power waste, bypass that and supply 5v direct it would use even less power :)

http://forum.arduino.cc/index.php?topic=83612.0

claims

Quote

From the spec sheet:

• Power Consumption at 1MHz, 1.8V, 25°C
- Active Mode: 0.2mA
- Power-down Mode: 0.1?A
- Power-save Mode: 0.75?A (Including 32kHz RTC)




500/0.0002 amps

So that's uh..

250,000,0

A lot of chips you could run from a 5v USB supply, but with the regulator, the chip for USB communication add it all up, its still a lot of uno's.... off a 5v usb supply.

dbutler0526

I hav a drone that has a usb video record slot.....i was gonna put blinking police lights on drone, powering the arduino via usb ....will that work

dbutler0526

How many volts will the digital pins then supply.... on the spec sheet its says the input voltage 7 to 12v.....usb supplies 5v how can it run with 5?

mmcp42

if you power through the power connector it can handle 7 to 12 volts, drops it down to 5
if you power through USB - it's already 5 so nothing else required :)
there are only 10 types of people
them that understands binary
and them that doesn't

dbutler0526

Thanks how many volts will come out of the digital pins with usb powered

CrossRoads

USB supplies 5V+/-some %, say its 5%
Thus the USB range is 4.75V-5.25V. Call that Vcc.
Output pins will then supply up to 20mA at no less than Vcc-0.8V per the data sheet.
5V -> 4.2V,  so 4.75 -> 3.95V. You will find the output will be closer to Vcc when the current draw is less.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

CrossRoads

Also, regarding Reply #2, the Uno runs at 16 MHz.  Per Table 29-9 of the 328P datasheet, the device draws 5.2 to 9mA at 8 MHz, 5V. 16 MHz would be higher (not spec'ed). Current draw triples from 4 MHz to 8 MHz, so doubling from 8MHz to 16 MHz a similar jump from 5.2/9mA up to 15.6/27mA might be expected.

The ATmega328P draws current, the ATmega16U2 draws current, the power LED draws current, the 3.3V regulator draws current, the Vin/USB comparator draws current - did I miss anything? All those add up, so at a steady state condition with no IO loads, you will probably measure 15-20mA being used.
500mA/(20mA/Uno) = ~25 Uno could be powered from 1 USB port.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

CrossRoads

You can also run the Uno from a USB wallwart:
Here are some examples
http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=usb%20wallwart#/ref=nb_sb_ss_i_0_11?url=search-alias%3Daps&field-keywords=usb+wall+adapter&sprefix=usb+wall+ad%2Caps%2C290&rh=i%3Aaps%2Ck%3Ausb+wall+adapter
Similar can be found for car use
http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=usb%20wallwart#/ref=nb_sb_ss_i_0_11?url=search-alias%3Daps&field-keywords=usb+car+adapter&sprefix=usb+wall+ad%2Caps%2C290&rh=i%3Aaps%2Ck%3Ausb+car+adapter
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

dbutler0526

Srry but u confused me alot lol.....will i be able to run the arduino and hav 2 red and 2 blue leds blink using my drone usb port?

dbutler0526

Will i be able to run the arduino and  2 red leds and 2 blue leds blinking off of my drone usb video recording 5v port?

CrossRoads

The drone puts out 5V on USB cable? 100mA or so?
Yes, you can run the arduino from that.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

dbutler0526

It puts out 5v and probly over 100ma because i already put 8 leds on it before each at 20mA

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