ATtiny13を使用したプログラマブル・ディバイダ

C言語コード

/*
 * DeviderCounter.c
 *
 * Created: 2016/02/11 1:00:41
 *  Author: 市川ゆり子
 */ 

/*
Programmable Divider by tiny13 + DIP SW

--Fuses--
HIGH: 0xFD LOW:0x7A
SPIEN *
BODLEVEL 1V8
SUT_CKSEL INTRCOSC_9MHZ6_14CK_64MS

--PIN Connection--
1 RESET: N/C
2 PB3:   DIP SW bit 4
3 PB4:   DIP SW bit 2
4 GND:   GND
5 OC0A:  Divider signal out
6 PB1:   DIP SW bit 1
7 T0:    Divider signal in
8 Vcc:   +5V
*/

#include <avr/io.h>

char readDIPsw();

int main(void)
{
	//Peripheral initialize.
	DDRB  = 0b00100001;	//DDRB0,5 is out. other is in.
	PORTB = 0b00011010; //PORTB1,3.4 pull up.
	
	OCR0A = (unsigned int) 0;	//init Counter Compare Register
	TCCR0A = (1 << COM0A0) + (1 << WGM01);	//OC0A pin Toggle, CTC counter mode.
	TCCR0B = (1 << CS01) + (1 << CS02);		//Counter clock source T0 pin (external).

    while(1)
    {
		OCR0A = 5 * readDIPsw();	//Read DIP SW and set it to Compare Register.
    }
}

//Read DIP SW state and return it.
char readDIPsw() {
	char bit0 = ~(PINB >> PINB1) & 0x01; //Read PINB1 state.
	char bit1 = ~(PINB >> PINB3) & 0x01; //Read PINB3
	char bit2 = ~(PINB >> PINB4) & 0x01; //Read PINB4
	
	return (bit2 << 2) | (bit1 << 1) | bit0;	//Joining bits.
}