void SPI_MasterInit(void) {
   SPCR = (1<<SPE)|(1<<MSTR)|(1<<SPR1)|(1<<SPR0);   /* Enable SPI, Master, set clock rate fck/16 */
}

void SPI_MasterTransmit(uint8_t cData) {
   SPDR = cData;                  /* Start transmission */
   while(!(SPSR & (1<<SPIF)));      /* Wait for transmission complete */
}void SPITransmitFreq(uint8_t Cnt, double F) { //F- значение частоты, Cnt - номер генератора
   dFi.w = F*167.77216; //частота передаваемая через SPI, какое-то фиксированное число 167.77216
   PORTB &= ~_BV(PB0);
   SPI_MasterTransmit(Cnt & 0x03);//0x03-маска
   SPI_MasterTransmit(dFi.b[0]);//флаги передачи
   SPI_MasterTransmit(dFi.b[1]);//флаги передачи
   SPI_MasterTransmit(dFi.b[2]);//флаги передачи
   PORTB |= _BV(PB0);
}

#include <tiny2313.h>
#include <math.h>
#include <io.h>

#define  F_CPU (8000000)
#define  VFG_TIMER_MAX (65535)
#define  VFG_DDR DDRB
#define  VFG_PORT PORTB

#define CS    PORTD3     // Chip select
#define DO    PORTB6     // MISO or Data Out
#define USCK  PORTB7     // Clock

unsigned int fG;
unsigned int fG1;
unsigned int fG2;
unsigned int fG3;
unsigned char nG;
unsigned int N[]={1,8,64,256,1024};

volatile char reqID = 0;  // This is for the first byte we receive, which is intended to be the request identifier
volatile unsigned char index = 0;  // this is to send back the right element in the array

//***********************************************USI************************************************

void SpiSlaveInit() {
    #asm("cli")
    USICR = ((1<<USIWM0)|(1<<USICS1)); // Activate 3- Wire Mode and use of external clock but NOT the interrupt at the Counter overflow (USIOIE)
    PORTB |= 1<<CS;                     // Activate Pull-Up resistor on PB0
    PCMSK|=1<<CS;                       // Active Interrupt on PB1
    GIMSK|=1<<PCIE; // General Interrupt Mask Register / PCIE bit activates external interrupts
    #asm("sei")
}

// External Interrupt 0 service routine
interrupt [EXT_INT1] void ext_int1_isr(void) {   
   
    if((PIND & (1<<CS))== 0){

// If edge is falling, the command and index variables shall be initialized
// and the 4-bit overflow counter of the USI communication shall be activated:

    reqID = 0;
    index = 0;
    USICR |= (1<<USIOIE);
    USISR = 1<<USIOIF;      // Clear Overflow bit
    }
    else{
// If edge is rising, turn the 4-bit overflow interrupt off:     
    USICR &= ~(1<<USIOIE);
    }
}

interrupt [USI_OVERFLOW] void usi_ovf_isr(void) {
switch(reqID) {
// Switch-Case to respond according to request from Master:
    case 0:               // If reqID value is zero (just initialized), then first message is the reqID.
    reqID = USIDR;      // Read in from USIDR register
    USISR = 1<<USIOIF;  // Clear Overflow bit         
    case 'T':
// Write value to send back into USIDR and clear the overflow bit:
    USIDR = nG & 0x03;
    USISR = 1<<USIOIF;       
    index++;            // Increment index to transmit the folloing element next
    break;         
    case 'H':       
// Write value to send back into USIDR and clear the overflow bit:
    USIDR = fG1;
    USISR = 1<<USIOIF;
    index++;            // Increment index to transmit the folloing element next
    break;
// Write value to send back into USIDR and clear the overflow bit:
    case 'B':
    USIDR = fG2;
    USISR = 1<<USIOIF;
    index++;            // Increment index to transmit the folloing element next
    break;   
// Write value to send back into USIDR and clear the overflow bit:
    case 'I':
    USIDR = fG3;
    USISR = 1<<USIOIF;
    index++;            // Increment index to transmit the folloing element next
    break;   
    default:
// Default option of Switch-Case. Send 'reqID' back for debugging.
    USIDR = reqID;
    fG=fG1+fG2+fG3;
    USISR = 1<<USIOIF;         
    }     
}

//***********************************************timer1************************************************
void Tim1Init(void)
{
    #asm("cli")
    TCCR1A = (1<<COM1A0); //toggle on compare
    TCCR1B = (1<<WGM12)|(1<<CS12)|(1<<CS10); // set timer CTC mode, prescaler 1024
    TIMSK = (1<<OCIE1A);
    #asm("sei")
}

void SetUpTim1A(unsigned int Foc)    //set value OCR1A register
{
 unsigned int TimDiv;
 unsigned char ClockSelect=0;
 unsigned char i;
 for(i=0;i<=4;i++) {
    TimDiv = (F_CPU/(2*16*Foc*N[i])-1);
    if(TimDiv >= 0 && TimDiv<VFG_TIMER_MAX){
     ClockSelect=i+1;
     break;
    }
 }
    #asm("cli")
    OCR1A = TimDiv;
    TCCR1B = (1<<WGM12) | (ClockSelect<<CS10);
    #asm("sei")
}

void UpdateTim1A(unsigned int freq) //хранение старого значения
{
   static unsigned int fG_old = 0;

   if (fG_old != freq)
   {
      SetUpTim1A(freq);
      fG_old = freq;
   }
}

void set_out_pin (unsigned char num){
nG=1<<num;
VFG_DDR = nG;
}

interrupt [TIM1_COMPA] void timer1_compa_isr(void)
{
VFG_PORT = (VFG_PORT^nG)&(nG);
}

void main(void)
{
 static unsigned int fG_old = 0;
 SpiSlaveInit();
 Tim1Init();
 UpdateTim1A(fG);
 
#asm("sei")
for(;;) {
 if (fG_old != fG) {   //проверка, не изменилось ли старое значение
    SetUpTim1A(fG);
    fG_old = fG;
 }
 //nG=0;     //номер генератора
 //fG=773;  //частота генератора
 set_out_pin (nG);
 SetUpTim1A(fG);
 }
}