!HELP! BOGUS readings!!!!!

lpcware — Wed, 15 Jun 2016 21:34:49 GMT

Content originally posted in LPCWare by jose_peeterson on Thu Sep 27 02:55:02 MST 2012
Dear all,
I am using the Sharp IR distance sensor (4 - 30cm) with LPC1769 using ADC to measure readings. I am using channel 2 (p0.25). I am using the START NOW method to read data in an infinte loop. the following is my code.

MY HEADER Files are from LIB MCU.


#include "stdio.h"
#include "stdint.h"
#include "lpc17xx_adc.h"
#include "lpc17xx_pinsel.h"
#include "LPC17xx.h"

//#define LPC_ADC               ((LPC_ADC_TypeDef *) LPC_ADC_BASE)

static void adc_pinsel();


int main(void)
{// //done for AD0.2 ONLY.

 uint16_t digi_distance = 0;
 uint32_t start_t = 0;

 adc_pinsel();


 ADC_Init(LPC_ADC,12500000);   

 ADC_BurstCmd(LPC_ADC,DISABLE);



  while(1)  // use a volatile variable to break this loop
  {
ADC_ChannelCmd(LPC_ADC,ADC_CHANNEL_1,DISABLE);
ADC_ChannelCmd(LPC_ADC,ADC_CHANNEL_2,DISABLE);
ADC_ChannelCmd(LPC_ADC,ADC_CHANNEL_3,DISABLE);
ADC_ChannelCmd(LPC_ADC,ADC_CHANNEL_4,DISABLE);
ADC_ChannelCmd(LPC_ADC,ADC_CHANNEL_5,DISABLE);
ADC_ChannelCmd(LPC_ADC,ADC_CHANNEL_6,DISABLE);
ADC_ChannelCmd(LPC_ADC,ADC_CHANNEL_7,DISABLE);

ADC_ChannelCmd(LPC_ADC,ADC_CHANNEL_2,ENABLE);

ADC_StartCmd(LPC_ADC,ADC_START_NOW);


while(!(ADC_ChannelGetStatus(LPC_ADC,ADC_CHANNEL_2,1)));
 digi_distance = ADC_ChannelGetData(LPC_ADC,ADC_CHANNEL_2);
     printf("%d\n",digi_distance);
  }


return 0;
}


static void adc_pinsel()
{
PINSEL_CFG_Type PinCfg;

PinCfg.Funcnum = 1; // select AD0.2
PinCfg.Pinnum = 25;
PinCfg.Portnum = 0;
PinCfg.Pinmode = 2;
PinCfg.OpenDrain = 0;
// select AD0.3


/* do the similarly for rest of the 3 pins*/

PINSEL_ConfigPin(&PinCfg);
}

my results are as follows. My voltmeter reading was 1.65v so it should give me steady reading around 2000 to 3000.

PLEASE HELP ME, I AM DESPERATE.

Re: !HELP! BOGUS readings!!!!!

lpcware — Wed, 15 Jun 2016 21:34:50 GMT

Content originally posted in LPCWare by fjrg76 on Thu Sep 27 17:57:22 MST 2012
And ... what was the question?

Re: !HELP! BOGUS readings!!!!!

lpcware — Wed, 15 Jun 2016 21:34:50 GMT

Content originally posted in LPCWare by daniel.widyanto on Fri Sep 28 00:08:50 MST 2012
Read this application notes: AN10974 - LPC176x/175x 12-bit ADC design guidelines

topic !HELP! BOGUS readings!!!!! in LPCXpresso IDE

!HELP! BOGUS readings!!!!!

Re: !HELP! BOGUS readings!!!!!

Re: !HELP! BOGUS readings!!!!!