how to check if arduino connected to pc?

Projects Programming
1

hi all,
i powered arduino form battry,
i want arduino check if it connect to pc via usb and is running

can anybody write the code for me :slight_smile:

thank you

2

Nope - go into the Learning section and browse the serial port tutorial, see if you can figure it out, then come back for help.

3

ok thank you i will check it ,
thank you

4

thank you sir,
that's helpful informations,

i have arduino duemilanove,

"connect to pc via usb and is running"

not system is runnig , i want to check if pc is powerd on,
(my project i have use arduino to turn off pc if i leave my car [car pc project] for one min, and start pc after engine start )

anyway thank you so much
regards

5

so from send datas from arduino to pc, like 'are you there ?"

If the pc is not responding, you can consider after few seconds or minutes that the pc is off.

Not diffuclt to code.

6

thank you,
but i am very new to this programing language so if you know any post please provide it or if anybody help me tell me where to start
thanks

7

i powered arduino form battry,
i want arduino check if it connect to pc via usb and is running

There may not be an easy way to do what you want to do. If the arduino is plugged into the usb port, it will probably power itself from the usb port unless the external power supply has significantly higher voltage than the usb 5v.

8

"significantly higher voltage than the usb 5v"

Well actually, Vin/2 must be higher then 3.3V from the FTDI chip or a 3.3v regulator.
Vin = PowerIn - diode drop.

Anyway to have the PC send out a slow serial stream when it is powered on?

9

Well actually, Vin/2 must be higher then 3.3V from the FTDI chip or a 3.3v regulator.
Vin = PowerIn - diode drop.

I'm talking about using the arduino external power barrel jack which apparently has a 7805 regulating chip and a power auctioneering chip which incurr some voltage dropping to accomidate supplying 5v on the arduino 5v bus. It appears one can always directly supply appropriate outside voltage to the desired arduino bus if desired.

10

We are talking the same thing- the barrel jack power is divided in half after the reverse protection diode and compared to 3.3V to control the switch.
Thus power jack in must be >(3.3*2 + 0.7) = ~7.3V or else USB power will be used if available.

11

I don't trust the external power control as when I connected 12v to the barrel connector, the arduino 5v pin measured over 8v.

12 
thank you,
but i am very new to this programing language so if you know any post please provide it or if anybody help me tell me where to start
thanks

Hey ejasoft, for some good arduino tutorial go to these links :

and follow on as there are 11 episodes.

13

thank you for this Replies and thank you vishalapr to this tutorial,
and i will search agian for this idea,

I want to ask you about if i porwerd arduino from car battry it will make my battry dead after few days or arduino not use alot of power?
I am very new to this electroinc world and try to make any project to learn form it

anyway thank you
regards

14

Your welcome, and about the car battery I really don't know as I'm new to the arduino as well but I have been doing it for about a month...So I'm sorry I cannot help you with that question.

15

Thank you so much vishalapr , i will also search for this and i will try it for two days and check for battry life, anyway thank you so much
regards

16

thank you KE7GKP, it's has no any thing added to arduino only the arduino and lm7805 to make sure that no more than 5volt, i will make simple project about car pc arduino just check for wether i have start engin or stop
thank you
regards

17

Car battery is measured in AmpHours of capacity, yes?

Arduino running for an our will use 0.04 to 0.05ampHours. Will run a long time.

@zoomkat, did you fry your regulator? Its output should not be at 8V.

18

did you fry your regulator? Its output should not be at 8V.

The first time I connected 12v to the barrel connector, the LEDs seemed a little brighter, so I checked the 5v pin and it was 8v+, so disconnected. Tried a 9v battery and the 5v pin was 7v+. Don't know what the problem is. Will have to use an external 7805 when not on the USB connector.

19

zoomkat:
The first time I connected 12v to the barrel connector, the LEDs seemed a little brighter, so I checked the 5v pin and it was 8v+, so disconnected. Tried a 9v battery and the 5v pin was 7v+. Don't know what the problem is. Will have to use an external 7805 when not on the USB connector.

for that i will use external 7805, cuz car altrenator output 13.5 ++ volt,

anthor question , can i use this AP07N70CP-A pdf, AP07N70CP-A Description, AP07N70CP-A Datasheet, AP07N70CP-A view ::: ALLDATASHEET :::
to fade 12 volt lamp? to connect it on pwm pin?

what is the rules on use any mosfet? can i use any one ?

thanks all for replys

20

Not a good choice - that one has 1.2ohm Rds - you really want something on the .00x ohm range, like 8-mOhm. Will run much cooler.
Also find a Logic Level part - that will turn full-in with arduino level outputs, vs only turning maybe 1/2 on with standard parts that typically need 10V to turn full on.

This one is okay, but you can find parts with lower Rds.