Query about MCP3201 and 8051 communication – program is given

[Sanket]

Dear sir/madam

 

In my following program I established complete SPI communication between 8051 & MCP3201, using SPI mode 00 (clock idles low) principle. Program works very well, but it has some problem. MCP gives counts ranging from 0000 to 4096 for 0% to 50% of POT position. For 50% to 100% POT position MCP again repeats counts ranging from 0000 to 4096. But i want count from 0000 to 4096 for the POT position from 0% to 100%. So what is the remedy to do that?

If anybody knows then please reply.

I have used keil v4 compiler and proteus 7.6 simulator.

 

 

/********PROGRAM*********/

 

 

#include <reg51.h>
#include <stdio.h>
#include <string.h>

sbit cs = P1^2;
sbit datao = P3^1;
sbit clko = P1^0;

#define lcdport    P0       //    LCD databus connected to PORT0

sbit rs = P2^0;         // Register select pin connected to P0.0
sbit rw = P2^1;         // Read Write pin connected to P0.1
sbit en = P2^2;         // Enable pin connected to P0.2

void lcd_ini();
void lcdcmd (unsigned char);
void lcddata (unsigned char);
unsigned int x, y, i = 0;
unsigned char temp_reg = 0;

union
{
    char databyte[2]; // declare temp array for adc data
    unsigned int result; // declare integer for adc result
} adc;

 

//***********ADC routine*********/

void Read_Adc( void )
{
    cs = 0;
    for(y=0;y<8;y++)
    {
        clko = 1;
        clko = 0;
        temp_reg <<= 1;
        temp_reg |= datao & 0x01;
    }adc.databyte[0] = temp_reg;
    temp_reg = 0;
    for(x=0;x<8;x++)
    {
        clko = 1;
        clko = 0;
        temp_reg <<= 1;
        temp_reg |= datao & 0x01;
    }
    cs = 1;
    adc.databyte[1] = temp_reg;
    temp_reg = 0;
    adc.result >>= 1; // adjust composite integer for 12 valid bits
    adc.result &= 0x0FFF; // mask out upper nibble of integer
}

 

//***************delay routine*****************//

 

void __delay_us(unsigned int us_count)
{    
    while(us_count!=0)
    {
        us_count–;
    }
}

 

 

void __delay_ms(unsigned int ms_count)
{
    while(ms_count!=0)
    {
        __delay_us(112);     //delay_us is called to generate 1ms delay
        ms_count–;
    }
}

/******************************
    MAIN CODE BEGINS HERE
******************************/
void main(void)
{
    unsigned int convert_value = 0;
    
    lcd_ini();

    while(1)
    {    
        Read_Adc(); // initiate MCP3201 conversion and read result
        convert_value=adc.result;
        lcdcmd(0x88);
        lcddata(((convert_value%10000)/1000)+48);    __delay_ms(10);   
        lcddata(((convert_value%1000)/100)+48);      __delay_ms(10);
        lcddata(((convert_value%100)/10)+48);       __delay_ms(10);
        lcddata((convert_value%10)+48);            __delay_ms(10);    
    }
}

void lcd_ini()
{
    lcdcmd(0x38);    __delay_ms(10);        // Configure the LCD in 8-bit mode, 2 line and 5×7 font
    lcdcmd(0x0C);    __delay_ms(10);        // Display On and Cursor Off
    lcdcmd(0x01);    __delay_ms(10);        // Clear display screen
    lcdcmd(0x06);    __delay_ms(10);        // Increment cursor
    lcdcmd(0x80);    __delay_ms(10);        // Set cursor position to 1st line, 1st column
}

void lcdcmd (unsigned char cmdout)
{
    lcdport=cmdout;        //Send command to lcdport=PORTB
    rs=0;                        
    rw=0;
    en=1;
    __delay_ms(10);
    en=0;
}

void lcddata (unsigned char dataout)
{
    lcdport=dataout;    //Send data to lcdport=PORTB
    rs=1;
    rw=0;
    en=1;
    __delay_ms(10);
    en=0;
}

 

 

[shailesh]

after many research in your program find out error……

 

 

remove rotation of bit in stored result at 15…..or make simple routine like

 

 

    //Routine for spi data read from mcp3201.   
unsigned int Get_ADC_Sample(void)    
{   
        unsigned int TempCount;   
        unsigned int Temp_Data=0;   
     
        SPI_CS_PIN=1;   
       
        for(TempCount=0;TempCount<16;TempCount++)                //counter for 16 databits   
        {   
            
                      SPI_CLK_PIN=0;
                        SPI_CS_PIN=0;                    
            SPI_CLK_PIN=1;
                   
                    if(TempCount!=15)   
           Temp_Data=Temp_Data<<1;  
                               
           
           if(SPI_DATA_PIN==1)
                            {Temp_Data = Temp_Data | 0x01;}  
                       
        }   
       
        SPI_CS_PIN=1;                                           //keep high when not doing the conversion.   
        Temp_Data &=0x0fff;                                     //mask upper 4 bits.   
        return Temp_Data;
                   
 }   
       
 

 

 

[AJISH ALFRED]

Hi Sanket,

Why don’y you try it on real hardware?

[Sanket]

Thank you shailesh,

 

i  must say you have taken very great efforts to my program.

it helps me a lot in solving my query……

after understanding your logic, i found the problem with my logic..

 

thanks again….

[Sanket]

Hello ajish,

 

As per your opinion with thistopic, i will definately try this code with real hardware as early as possible.

I’ll get back to you with my result soon.

 

thanks

[Author]

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