next topic »

[on:]

Hi all!
I'm new bie. Hope everyone help!
I'm using Arduino Nano v3.0 Board (ATM328P).
+ I use one potentiometer. It uses the reference source AREF
+ Frequency_Board uses +5V source on board.
I'm afraid that USB power is not enough to provide in my application
I hope everyone to explaine my problem.
Thank all!

[Reply #1 on:]

You should be OK.

[Reply #2 on:]

I don't understand the connection between the Inverter output and the 5V line.
( I guess it's a drawing problem only, and should go to Vcc pin of your 74HC14 )

If I understand http://arduino.cc/en/Reference/AnalogReference properly, there's an internal resistor, if you use AREF as a voltage source, which would affect your potentiometer reading.
Rather connect Vcc (ATMEGA Pin7)  to the high end of your pot, if you need the full 0..5V range.  (?)

I'm afraid that USB power is not enough to provide in my application

USB Power (max 500mA) is by far sufficient, IMHO.

[Reply #3 on:]

I hope everyone to explaine my problem.

No not at all. You said:-

I'm afraid that USB power is not enough to provide in my application

But you did not say what you thought that, what problems, if any, you were having.
Apart from using the Vref which you should not. And probably blowing up your 74HC14 buffer by connecting it to the power line, you seem to be making no other mistakes.

[Reply #4 on:]

Thanks your reply!
My purpose: I have a 3D program, my program will read value of sensors from Arduino board throught USB cable.  
+ Hardware:
According to the comments, I have to fix:

Is that right?
  * Frequency_board: Measuring frequency form encoder, sent to PC (my froject is written in VC++2008)
  * Potentiometer: Mesuring analog input (A0 pin), sent to PC (my project ís written in VC++2008)
+ Software:
  *Communication between PC and Arduino board:
      -I am writing an application in VC++2008. I use SerialPort Class (MSDN) (http://msdn.microsoft.com/en-us/library/system.io.ports.serialport.aspx) to read each byte that Arduino board posted
      -On the board,I use "Serial" to read requests from the computer (Serial.read, Serial.ReadBytes) and send the value of the sensor to the computer (Serial.write, Serial.print)
  *Progamming for chip:
      -Analog input: i use function "analogRead(A0)"
      -Frequency from encoder: I used library "FreqMeasure" of Paul Stoffregen (best for 0.1 Hz to 1 kHz)
---->>>>It is my understanding. I'm not sure about my methods. Hope you guide, please!
Thank in advance!

[Reply #5 on:]

Is that right?

Much better, still to remove the connection from c1 to pin2 of your 74HC14.
c1 is just between 5V and GND and intended to be parallel (and close to) to the power pins of the 74HC14 

"Software" is fine so far, IMU ( description is not as detailed as your circuit picture ) 

[Reply #6 on:]

Frequency_board

No need to have that buffer there.

[Reply #7 on:]

Hi all!
I'm new bie. Hope everyone help!
I'm using Arduino Nano v3.0 Board (ATM328P).
+ I use one potentiometer. It uses the reference source AREF
+ Frequency_Board uses +5V source on board.
I'm afraid that USB power is not enough to provide in my application
I hope everyone to explaine my problem.
Thank all!

You are fine. That circuit looks like it only uses a 10 to 20 milliamps. USB will give you 500 mA.

[Reply #8 on:]

Frequency_board

No need to have that buffer there.

I'll bet he's using that HC14 to sharpen up the detector output.

[Reply #9 on:]

That circuit still has the buffer output connected to 5V

[Reply #10 on:]

That circuit still has the buffer output connected to 5V

I know... but I figured that it's just a mistake in the drawing. Hopefully it's not ACTUALLY wired that way.

[Reply #11 on:]

@ *dhenry* a Schmidt trigger input inverting buffer is good engineering practice to 'clean up' the output of a photo-transistor.
The connection from the buffer output to Vcc isn't though.

Bob

{Edit}Data Sheet attached

[Reply #12 on:]

he's using that HC14 to sharpen up the detector output.

Which isn't needed at all: look at the pin's internal diagram.

[Reply #13 on:]

@ *dhenry* you are expecting my feeble brain to anticipate you... Which Pin? I see an NPN transistor, a photo transistor with a 104 resistor from collector + 'HC14 input to Vcc.
I don't see any "Pin" that would counter indicate the use of a schmitted buffer, replace it or in any other way mitigate the requirement... Let the rest of us in on your little secret because
I still don't see where my original observation has changed in any way...

@ *dhenry* a Schmidt trigger input inverting buffer is good engineering practice to 'clean up' the output of a photo-transistor.
The connection from the buffer output to Vcc isn't though.

Bob

[Reply #14 on:]

That circuit still has the buffer output connected to 5V

I know... but I figured that it's just a mistake in the drawing. Hopefully it's not ACTUALLY wired that way.

You're right. I draw the wrong. It must be like this:


Thank all comments!