Using MCP3208 with Arduino DUE

hello there!

this first time posting here, please forgive me if forget stuff.
i got problem using adc mcp3208 arduino due.

i want read out flexsensor using voltage divider , said adc. kinda working, value shaking lot , makes impossible read out value.

now read can add coupling capacitators. honest quite bad @ electronics , don't (not mcp datasheet) how use properly. have suggestions or maybe layouts can use orientation?

i not using library, code use read out adc this:

code: [select]


#include <spi.h>
#define _cs_pin_ 52 //pin 10 defined cs pin.
void setup()
{
  serial.begin(115200); //initalize serial port print analog readings mcp3208 onto teh terminal.
  pinmode(_cs_pin_,output); //pin 10 acting output cs output pin.
  digitalwrite(_cs_pin_,high);
  spi.begin(); //intialize spi port
  spi.setclockdivider(52, 84);


}

void loop()
{

     serial.println(readadc(4)); //reads cahnnel 0 mcp3208 , prints value. change if u want t o read other cahnnel.
     delay(2000); //delay
}

uint16_t readadc(int channel)
{
  uint16_t output;
  byte channelbits = channel<<6;

 //if(channel>3)
 
  //select adc
  digitalwrite(_cs_pin_, low); //select connected mcp3208 pulling _cs_pin_ low.
  if(channel>3)
    spi.transfer(b00000111); //defines single mode of operation adc. d2=1 start bit. d1=1 sinfgle ended mode d0=0 channel 0-3. 1 channel 4-7
  else
    spi.transfer(b00000110);

  byte msb = spi.transfer(channelbits); //transfers 2nd byte mcu mcp3208 returns  msb of read data.
  byte lsb = spi.transfer(0x00);//transfers 3rd byte mcu mcp3208 returns  lsb of read data.
 
  digitalwrite(_cs_pin_,high); //deselect connected mcp3208 pulling _cs_pin_ high.
 
 
  msb = msb & b00001111; // make 4 higher bits of msb 0 12 bit resolution provided mcp3208
 
  output = msb<<8 | lsb; //combine msb lsb form 12 bit analog read  value.

  return output; //output value
}

i didn't make myself, got here: https://github.com/oksbwn/mcp3208_arduino/blob/master/mcp3208_with_arduino.ino


this part of current layout. powering (vdd) mcp 5v spi pin header, not 3.3v.

would happy if maybe has got few suggestions!

not coupling capacitors decoupling capacitors. chips must have 0.1uf ceramic capacitor between power , ground.

connecting analog , digital grounds on chip not taking them different ground pins on arduino.

also capacitor input analogue ground close chip help.

if using solderless bread board noise in readings.

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