ATMega32 SPI Interfaces To SN74HC164 And LED

ATMega32 contains an SPI communication module. This type of communication interface typically uses 3 wires plus chip select pins. However this controller uses only two pins - serial data and serial clock pin to interface with SN74HC164 parallel out shift register chip.

Simulating Program

SN74HC164 DIP-14

I use Hardware SPI with the clock rate Fosc/4. Microcontroller clock is internal RC running at 4MHz.

/*
 * SPI74164LED.c
 *
 * Created: 7/7/2023 9:16:53 AM
 * Author : Admin
 */ 
 
#include <avr/io.h>
 
#define F_CPU 4000000UL
#include <util/delay.h>
 
void masterInit(void){
	/*Set MOSI, SCK and SS Output*/
	DDRB|=(1<<4)|(1<<5)|(1<<7);
	/*Enable SPI Master Set Clock Rate Fclk/4*/
	SPCR|=(1<<SPE)|(1<<MSTR);
}
 
void masterTransmit(char spiData){
	/*Start The Transmission*/
	SPDR = spiData;
	/*Wait For Completion*/
	while(!(SPSR&(1<<SPIF)));
}
 
 
int main(void)
{
    masterInit();
 
    while (1) 
    {
		masterTransmit(0xF0);
		_delay_ms(1000);
		masterTransmit(0xAA);
		_delay_ms(1000);
		masterTransmit(0x0F);
		_delay_ms(1000);
    }
}
 
 

Click here to download its source file.