#include <avr/io.h>
#include <util/delay.h>
#include <modbus.h>
#include <avr/interrupt.h>

volatile uint16_t holdingRegisters[4];
void modbusGet(void);

int main(){
    DDRD |= (1 << 4); // LED
    DDRD |= (1 << 3); // FU PWM
    DDRD |= (1 << 2); // 485 DE

	PORTD|=(1<<0); // RX

    // FU PWM on PD3
    OCR2B = 12;
    TCCR2A |= (1 << COM2B1);
    TCCR2A |= (1 << WGM21) | (1 << WGM20);
    TCCR2B |= (1 << CS21);

	sei();
	modbusSetAddress(1);
    modbusInit();

    // Modbus Tick Timer
    TCCR0B|=(1<<CS01); //prescaler 8
	TIMSK0|=(1<<TOIE0);

    while(1){
        _delay_ms(10);
        OCR2B += 1;
	    modbusGet();
    }
}

ISR(TIMER0_OVF_vect) { //this ISR is called 9765.625 times per second
	modbusTickTimer();
}

void modbusGet(void) {
	if (modbusGetBusState() & (1<<ReceiveCompleted))
	{
		switch(rxbuffer[1]) {
            case fcReadHoldingRegisters:
                modbusExchangeRegisters(holdingRegisters,0,4);
                break;
            case fcPresetSingleRegister:
				modbusExchangeRegisters(holdingRegisters,0,4);
			case fcPresetMultipleRegisters: 
				modbusExchangeRegisters(holdingRegisters,0,4);
                if(holdingRegisters[0])
                    PORTD |= 1 << 4;
                else
                    PORTD &= ~(1 << 4);

                break;
            default:
				modbusSendException(ecIllegalFunction);
                break;
		}
	}
}