CMcp4242.h

#pragma once

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

// This is the interface for the MCP4242 Microchip dual digital pot
// 0 - 6.27K  127 - 56.19K
// 1 - 6.66K  128 - 56.60K
// 2 - 7.05K  129 - 56.60K

// Forth Word(s)
void readPot(void);             // pot# -- value
void writePot(void);    // value pot# --

class CMcp4242 : CSpi
{
private:
protected:
        // Command Format: AAAA CC DDDDDDDDDD
        // Support constants
        static const int  addressShift = 12;
        static const int  commandShift = 10;
        static const int  dataMask     = 0x1FF;

        // Commands
        static const char writeCmd = 0;
        static const char readCmd  = 3;

        // Memory Map
        static const char wiper0   = 0; // RAM
        static const char wiper1   = 1; // RAM

        static const char wiper0nv = 2; // EEPROM
        static const char wiper1nv = 3; // EEPROM

        static const char tcon     = 4;
        static const char status   = 5;
        
        static const char EEWA     = 4; // Status bit
        
        // Addresses 6 - 15 are user data registers in EEPROM
        
protected:
public:
        static void init(void)
        {
                CSpi::init();   // Call base class init()
        }
        // Command Format:
        // AAAA CC DDDDDDDDDD
        static void write(int address, int data)
        {
                writeWord((address  << addressShift) |                  // Address
                                  (writeCmd << commandShift) |                  // Write command
                                  (data & dataMask));                                   // Data
        }

        static int  read(unsigned int address)
        {
                return writeWord((address << addressShift) |    // Address
                                                 (readCmd << commandShift));    // Read command 
        }
};