2120_driver.c

MAX2120 driver for DVB-S STB

//***********************************************************************
//***********************EVKIT FUNCTIONS  *******************************
//***********************************************************************
/*
  Name: 2120_Driver.cpp
  Copyright: Maxim IC
  Author: Paul Nichol
  Date: 14/03/06 12:35
  Description: Contains functions to communicate and control the MAX2120 IC.
  This unit depends on Lpt and I2c functions located in the file Lpt_Functions.cpp
  These Lpt and I2c functions are only needed for the PC->parallel port->MAX2120 control
  and can be replaced with the microprocessor specific I/O functions to write to
  the IC.
*/
//***********************************************************************


#include <math.h>
#include <string.h>
#include <stdlib.h>
#include <windows.h>      //microsoft specific

#include "2120_Driver.h"

#include "LPT_Functions.h"  //Relates to printer port driver. Omit for microprocessor based applications




//   Assign default values for each register
unsigned char N_High = 0x3;          
unsigned char N_Low = 0xB6;         
unsigned char Frac2 = 0x2;
unsigned char Frac1 = 0xF6;
unsigned char Frac0 = 0x84;
unsigned char Xtal = 0x04;      //Rdiv = 2 
unsigned char PLL_Conf = 0xA8;      
unsigned char VCO_Cont = 0xCF;      
unsigned char BB_LPF = 0x4b;
unsigned char Standby = 0x40;    //lower 4 bits set the baseband gain!
unsigned char Shutdown = 0x00;
unsigned char Test = 0x08;
unsigned char Status = 0x00;
unsigned char AutoTune = 0x00;
unsigned char TrimConfig = 0x00;
unsigned char BiasTrim = 0x27;
unsigned char BB_FiltTrim = 0xd;
unsigned char RF_ContTrim1 = 0x5d;
unsigned char RF_ContTrim2 = 0x5;


double XtalRef = 4;     //Frequency in MHz applied to MAX2120 Xtal pin.



//PC functions to close communications with the MAX2120, 
//omit for microprocessor based applications
void MAX2120Close(void)
{
     LPT_Close();
}        


//******************************************************************************
//This Init routine must always be called before any I2C Communication can occur.
//It sets up the register defaults for the Max2120 in order to operate properly.
//******************************************************************************

void MAX2120Init(void)
{
	  
      //PC functions to set up communications with MAX2120, 
      //omit for microprocessor based applications
      LPT_Init("MAX2120_cpp");
      I2C_SCLKO_PIN ( 3 );   
      I2C_SDAO_PIN ( 2 );
      I2C_SDAI_PIN  ( 10 );


      //Initialize the registers in the MAX2120:
      MAX2120Write(MAX2120_N_HIGH, N_High);          
      MAX2120Write(MAX2120_N_LOW, N_Low);         
      MAX2120Write(MAX2120_CP_FRAC2, Frac2);
      MAX2120Write(MAX2120_FRAC1, Frac1);
      MAX2120Write(MAX2120_FRAC0, Frac0);
      MAX2120Write(MAX2120_XTAL, Xtal);
      MAX2120Write(MAX2120_PLL, PLL_Conf);      
      MAX2120Write(MAX2120_VCOCONT, VCO_Cont);      
      MAX2120Write(MAX2120_BASEBAND, BB_LPF);
      MAX2120Write(MAX2120_STANDBY, Standby);
      MAX2120Write(MAX2120_SHUTDWN, Shutdown);
      MAX2120Write(MAX2120_TEST, Test);
      MAX2120Write(MAX2120_TRIMCONF, TrimConfig);
      MAX2120Write(MAX2120_BIASTRIM, BiasTrim);
      MAX2120Write(MAX2120_BBFILTTRIM, BB_FiltTrim);
      MAX2120Write(MAX2120_RFCONTTRIM1, RF_ContTrim1);
      MAX2120Write(MAX2120_RFCONTTRIM2, RF_ContTrim2);
                   
}



//******************************************************************************
//
//The routine MAX2120SetFrequency will set the following registers based
//on the input Frequency (MHz)
//    
//******************************************************************************

void MAX2120SetFrequency(double Frequency)
{
   int VCO_Divider=1;
   int Rdiv; 
   long NDiv;
   const RDIV_MASK = 0x1f; //Rdiv is Reg 5 D0-D4 
   
   //Set the DIV24 bit, 1 = LO divided by 4, 0 = LO divided by 2.
   if ( Frequency <= 1125 )          
   {
      PLL_Conf |= 0x80;    //DIV24 Bit = 1
   }
   else{
      PLL_Conf &= 0x7f;   //DIV24 Bit = 0
   }
   
   Rdiv = Xtal & RDIV_MASK;  
   NDiv = (long)(Frequency * Rdiv) / (XtalRef);   //Find the multiplier (n + fracn) ex. 50.27234
	
   N_High = (unsigned char)((NDiv & 0x7f00) >> 8); //Retain the upper bit which is the FRAC Bit.
   N_Low = (unsigned char)NDiv & 0xff;

   //Write out the new register changes to the IC
   MAX2120Write(MAX2120_PLL, PLL_Conf);
   MAX2120Write(MAX2120_N_HIGH, N_High);
   MAX2120Write(MAX2120_N_LOW, N_Low);
   
}

//******************************************************************************
//   Reads the LD or lock detect bit, Returns 1 if th PLL is locked, 0 if not locked.
//******************************************************************************

unsigned char MAX2120_LockDetect(void){
   return (MAX2120Read(MAX2120_STATUS) & LD_BIT) >> 4;
}

//
//MAX2120Read will read and return the value in register 'reg_index'
//Customer's I-squared-C read function would go in place of this wrapper
//function.  This funciton takes a register index to indicate which register
//to read from.
//See the Max2120 data sheet for the I-squared-C read sequence.
//

unsigned char MAX2120Read(unsigned char reg_index)
{
	 return I2C_IReadByte(MAX2120_ADDR,reg_index); 
}

//
//MAX2120Write will write to register 'reg_index' the value 'value'
//Customer's I-squared-C write function would go in place of this wrapper
//function.  This funciton takes a register index to indicate which register
//to read from and a value to put into the register.
//See the Max2120 data sheet for the I-squared-C write sequence.
//
void MAX2120Write(unsigned char reg_index,unsigned char value)
{
     I2C_IWriteByte(MAX2120_ADDR, reg_index, value);
}