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MCP3201 (microchip) is 12 bit adc

 
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oyhan



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Posts: 21
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MCP3201 (microchip) is 12 bit adc
PostPosted: Fri Aug 11, 2006 1:25 am     Reply with quote
Dear Friends..
MCP3201 is 12 bit adc on SPI communication. Below is sample program that is not working. Can some one guide me where is mistake. Thanks..


Code:

#include <16F88.h>
#fuses INTRC_IO, MCLR, NOWDT, NOPROTECT, NOBROWNOUT, PUT, NOLVP
#use delay(clock=8000000)
#include "flex_lcd.c"

#define Dout   PIN_B0
#define CLK   PIN_B1
#define CS   PIN_A0

// Define the register addresses for ANSEL and CMCON.
#byte ANSEL = 0x9B
#byte CMCON = 0x9C

BYTE read_adc_byte(BYTE number_of_bits) {
   BYTE i,data;

   data=0;
   for(i=0;i<number_of_bits;++i) {
      output_low(CLK);
      delay_us(50);
      shift_left(&data,1,input(Dout));
      output_high(CLK);
      delay_us(50);
   }
   return(data);
}

void main()
{  int  data_l;
   long int data_h, value;
   float result;
   data_h=0;
   data_l=0;
   set_tris_a(0b11100000);  set_tris_b(0b00000001);
   ANSEL = 0;  // Set all A/D pins to digital
   CMCON = 7;  // Disable comparators
   setup_adc(ADC_OFF);   output_high(PIN_A1); output_high(PIN_A2); output_high(PIN_A3); output_high(PIN_A4);
   lcd_init();  delay_ms(500);  lcd_putc("Value:");

while(1) {
      output_high(CS);
      delay_us(1);
      output_low(CS);
      data_h = read_adc_byte(9);
      data_l = read_adc_byte(4);
      output_high(CS);
      value = (data_h << 4) | data_l;
      lcd_gotoxy(7,1);
      printf(lcd_putc,"%0Lu",value);
      delay_ms(250); delay_ms(250);
}
}


Last edited by oyhan on Sun Aug 13, 2006 5:18 am; edited 1 time in total
oyhan



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PostPosted: Fri Aug 11, 2006 3:46 pm     Reply with quote
Can some one guide me where is mistake. Thanks..
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Fri Aug 11, 2006 3:49 pm     Reply with quote
CCS has many examples of how to do software SPI read operations.
They use the shift_left() function. Look at the MCP3204 driver for
an example. It's in this folder: c:\Program Files\Picc\Drivers
akokyaw



Joined: 11 Feb 2005
Posts: 24

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MCP3202
PostPosted: Sun Aug 13, 2006 1:08 am     Reply with quote
Hi,
Try this code,


Code:
#include <16F877.h>
#fuses XT,NOWDT,NOPROTECT,NOLVP
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)  // Jumpers: 8 to 11, 7 to 12

#define CLK  PIN_B0
#define Dout PIN_B1
#define Din  PIN_B2
#define CS   PIN_B3


void ShiftOut (int data, int no_of_bit)
{
   int i;
   for(i=0 ; i<no_of_bit>>= 1;
      output_high(CLK);
      delay_us(50);
    }
}

BYTE read_adc_byte(BYTE number_of_bits) {
   BYTE i,data;

   data=0;
   for(i=0;i<number_of_bits;++i) {
      output_low(CLK);
      delay_us(50);
      shift_left(&data,1,input(Dout));
      output_high(CLK);
      delay_us(50);
   }
   return(data);
}

void main()
{

   int  data_l;
   long int data_h, value;
   float result;
   data_h=0;
   data_l=0;

   printf("\r****  Initializing of MCP3202 12 Bit A/D Converter ****\n ");

   while(1) {
      output_high(CS);
      delay_us(1);
      output_low(CS);

      ShiftOut(0b00001100, 4);

   data_h = read_adc_byte(9);
   data_l = read_adc_byte(4);
   output_high(CS);
   value = (data_h << 4) | data_l;
   result = value * 0.001226;
      printf("\rOutput Voltage = %f V", result);
      delay_ms(250); delay_ms(250);
   }
}





hope it will help you,

regards,
ako
Code:
oyhan



Joined: 03 Jun 2005
Posts: 21
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PostPosted: Sun Aug 13, 2006 5:29 am     Reply with quote
Thanks akokyaw But I want to use mcp3201 . Only 3 Data port and only Dout . It Does not use DIn. I thing I convert your code for mcp 3201 but It did not run. (New code is in my first message) I saw some problem. For example (for any voltage between 0-5V); Always.. First time Value = 03071 and second time is Value=1024 totaly is 4095. I think it musn't change this value but I do not understand why?? I have to see only one Value on the lcd why not?? Help me please..
Best Regards..
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Sun Aug 13, 2006 2:44 pm     Reply with quote
I didn't analyze your code in detail, but I can see one problem.

You're calling the "read_adc_byte()" function, and requesting it to
get a 9-bit value. Example: read_adc_byte(9);
But the function puts the data into a byte (8-bits), and it returns a byte.
It can't get 9 bits. You need to create a "read_adc_word()" function
that can get up to 16 bits.
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