DownconverterFirmware/main.c

#include<avr/io.h>
#include "common.h"

// PB3 - ADF4350 LE
// PB2 - SCK to ADF4350 CLK
// PB1 - DO (MOSI) to ADF4350 DATA
// PB0 - ADF4350 LD
// PB4 - Status LED

void Delay(uint32_t);
uint8_t SendReceiveSPIData(uint8_t);
void SendSPIDataADF4350 (uint32_t);

int main()
{
  // set instructions to configure the ADF4350 for a 1 GHz +5dBm output
  uint32_t ar0=0x500000;
  uint32_t ar1=0x8008011;
  uint32_t ar2=0x4e42;
  uint32_t ar3=0x4b3;
  uint32_t ar4=0xac803c;
  uint32_t ar5=0x580005;

  // alternative instructions for a 1001.25 MHz +5dBm output
  //uint32_t ar0=0x500008;
  //uint32_t ar1=0x8008029;
  //uint32_t ar2=0x4e42;
  //uint32_t ar3=0x4b3;
  //uint32_t ar4=0xac803c;
  //uint32_t ar5=0x580005;

  // set direction of PB1 (DO) and PB2 (USCK) as output
  DDRB=(1<<PB1)|(1<<PB2);

  // set to three wire mode (SPI)
  USICR=(1<<USIWM0);          
  ///USICR=(0<<USIWM1); not needed, already 0

  // set direction of PB4 (status LED) as output
  DDRB |= (1 << PB4);

  // set direction of PB3 (LE) as open-drain output
  DDRB |= (1 << PB3);

  // set PB3 (LE) low
  PORTB &= ~(1 << PORTB3);

  // set direction of PB5 (LD Input) as input
  DDRB &= ~(1 << DDB0);

  // enable pull-up resistor on PB5
  PORTB |= (1 << PORTB5);

  // flash the Status LED (PB4) to show that everything works
  PORTB |= (1 << PORTB4);
  Delay(500000);
  PORTB &= ~(1 << PORTB4);
  Delay(100000);

  // enter loop waiting for frequency lock to be achieved
  while (1)
  {
      // read the state of LD (PB5)
      uint8_t ldState = PINB & (1 << PINB5);

      // if LD is low, turn on the LED (PB4)
      if (ldState == 0)
          PORTB |= (1 << PORTB4); // Turn on the LED
      else
          PORTB &= ~(1 << PORTB4); // Turn off the LED
  }
}

// general purpose delay
void Delay(uint32_t tmax)
{
  uint32_t i;
  for (i=0;i < tmax ; i++) 
    {
    asm("nop");
    }
}

// send an 8 bit word via SPI1 and receive an 8 bit word at the same time
uint8_t SendReceiveSPIData(uint8_t value)
{
  uint8_t lout = 0;
  short int i=0;
  
  // prob change the 8 below to len of value?
  for(i=0;i<8;i++)
  {
		///USIDR = value[i]; // wrong way to do it apparently, still saving for future reference
    USIDR = (value >> i) & 0x01;         // write data bytes in Data register, will cause them to get sent on clock
    while(USIOIF==0)        // check USI data counter overflow flag to detect the end of transmission every byte
    {
      USICR|=(1<<USICLK)|(1<<USITC);  // enable clock for transmission and generate clock for slave deivce
    }
    USISR|=(1<<USIOIF);      // clear USI data counter overflow flag
  }

  // Read in a 16 bit frame 
  ///uint16_t inbyte = *(uint32_t *)(SPI1_BASE + 0x0c);
  //return inbyte;
}

// send a 32 bit register value to the ADF4350
void SendSPIDataADF4350 (uint32_t outval)
{
  // split into 4 x 8-bit words
  uint8_t byte1 = (outval & 0xFF000000) >> 24;
  uint8_t byte2 = (outval & 0x00FF0000) >> 16;
  uint8_t byte3 = (outval & 0x0000FF00) >> 8;
  uint8_t byte4 = outval & 0x000000FF;

  // send these to the ADF4350 via SPI
  SendReceiveSPIData (byte1);
  SendReceiveSPIData (byte2);
  SendReceiveSPIData (byte3);
  SendReceiveSPIData (byte4);

  // 2 x 16 version:
  // split into 2 x 16 bit words
  ///uint16_t highWord = (outval & 0xffff0000) >> 16;
  ///uint16_t lowWord = outval & 0x0000ffff;
  // send these to the ADF4350 via SPI
  ///SendReceiveSPIData (highWord);
  ///SendReceiveSPIData (lowWord);

  // delay so the clock has gone low before LE is taken high
  Delay(10);
  // pull LE high to load the data into the ADF4350 register
  PORTB |= (1 << PORTB3);
  // short delay while LE is high (minimum of 20ns)
  Delay(30);
  // pull LE low again
  PORTB &= ~(1 << PORTB3);
}