another thing is that I will just need 1 MHz pulse instead of 4 MHz... 

I think that would be easier. is there any way to directly output 1 MHz pulse from digital pin? I mean something like a function or library that could help me do it?...

So what i just need would be 1 MHz clock where I will use a counter to create 40 kHz

thank you

thank you very much for the information ..
I appreciate it...
another follow up question....


what is the max frequency at which the gpio ports could read digital data?...

I just need to know because as I said, I need 1 MHz pulses for my 12-bit ADC which will return 12-bits digital output to be stored by the arduino?...

thanks..

My problem is this:


my ultrasonic transmitter is connected to the arduino I/o pin which outputs a pulse of 40 kHZ high and low by simple:

      digitalWrite (transmitterPin, HIGH); //sets the transmitter to 5 V
      delayMicroseconds (9); //first half cycle of 40kHz
      digitalWrite (transmitterPin, LOW); //sets the transmitter to 0 V
      delayMicroseconds (9); //second half cycle of 40kHz


my adc for the receiver needs a clock pulse of 4 MHz which I want to get from arduino also..


the problem is they have to run simultaneously... meaning while the transmitter is pulsing high and low of 40 kHz, the arduino should also ouptut 4 MhZ clock pulse to drive my ADC IC. WHat should i do?


Thank you

gud day.
I am working with a serial lcd (4x20) SKD204-634 series..
Has anyone worked with this before?

the problem is that, when all the characters (4x20) are already used, I cannot clear the screen and I need to turn the lcd's power off and on in order to see the next characters to display..

does anyone have a code for clear() for this?

thank you very much

I'm sorry. i mean one that does not need 20 V supply? tnx

ok thank you. but is there another way that does not need a 12 V supply?

Hi guys! I just want to know the simplest way to amplify a 40kHz square wave?

the peak is 5 Volts coming from the digital pin of arduino?

I need about 20V. I will use it to drive an ultrasonic transmitter. Thank you.

@markT: yes, that's why I i'm going to use direct contact (no air gap), i am going to use a coupling material.

@grumpyMike : I tried the PWM but I cannot change the frequency. I am new to arduino and the PWM (default peroid is short)

then what could be the best way to do? and amplifier for the square wave? thanks

oh yes. that would make it 12.5
thank you very much!!!

int outPin = 8;                 // digital pin 8

void setup()
{
  pinMode(outPin, OUTPUT);      // sets the digital pin as output
}

void loop()
{
  digitalWrite(outPin, HIGH);   // sets the pin on
  delayMicroseconds(25);        // pauses for 25 microseconds     
  digitalWrite(outPin, LOW);    // sets the pin off
  delayMicroseconds(25);        // pauses for 25 microseconds     
}



>>will this program be ok to drive my ultrasonic transmitter?

@grumpy mike, I've tried the square wave but How can I get 40kHz? I tried the PWM but the frequency is quite low.

ok thank you very much!!!

i will try the square wave and the 555 as well.
sorry i'm just afraid to try the square wave because i'm afraid to break my sensor.

but then i guess I'll do it. thanks..

can 555 create nice 40 kHz sine wave? do you have any schematic? thanks

ULTRASOUND PENETRATES WOOD.

why are you saying that i'm avoiding your question? i mean what question anyway?
what i am doing may be too simple for you so I just need to know how to generate sine wave using arduino? that's all. thank you