40 KHz square wave generation for driving ultrasonic sensor

[mohsen_bmv]

I want to generate 40khz square wave by ATtiny 2313v microcontroller in order to drive my ultrasonic sensor, how could i do this?

 

[sky_123]

It is possible to generate 40kHz to a very high level of accuracy using a simple 555, which is easier and cheaper. Otherwise, with ATtiny2313, you could use the PWM
functionality.

 

[alexan_e]

Use a timer set to compare match that toggles the output

// Timer/Counter 1 initialization
// Clock source: System Clock
// Clock value: 16000,000 kHz
// Mode: CTC top=OCR1A
// OC1A output: Toggle
// OC1B output: Discon.
// Noise Canceler: Off
// Input Capture on Falling Edge
// Timer 1 Overflow Interrupt: Off
// Input Capture Interrupt: Off
// Compare A Match Interrupt: Off
// Compare B Match Interrupt: Off
TCCR1A=0x40;
TCCR1B=0x09;
TCNT1H=0x00;
TCNT1L=0x00;
ICR1H=0x00;
ICR1L=0x00;
OCR1AH=0x00;
OCR1AL=0xC8; // decimal 200
OCR1BH=0x00;
OCR1BL=0x00;