!HELP! BOGUS readings!!!!!

[lpcware]

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.

0
0
2
0
2
3
0
2
115
99
124
96
63
96
28
51
32
0
0
0
0
1
2
0
0
0
0
31
71
1
0
0
0
0
119
128
103
63
83
16
99
110
76
99
48
64
0
0
2
3
2
0
0
0
0
2
0
0
0
0
19
19
48
51
23
112
16
0
0
0
0
2
0
1
15
2
119
99
99
119
110
50
48
35
34
32
4
49
0
0
3
0
0
0
2
0
0
0
0
0
0
2
3
1
2
0
0
0
0
0
2
2
87
111
115
115
71
7
49
0
0
2
1
2
1
0
0
0
0
0
0
0
3
0
1
2
0
3
0
2
64
0
1
0
2
120
102
50
49
79
32
103
67
86
56
3
99
0
2
0
0
0
0
0
0
0
0
0
0
0
0
0
2
0
2
0
0
0
0
0
0
2
0
0
0
0
96
0
0
1
0
1
1
3
0
0
0
0
0
0
0
2
0
2
3
127
1
143
0
118
119
111
74
103
4
0
0
2
0
0
0
0
0
3
32
8
0
3
7
121
2
96
2
7
83
0
5
0
0
0
2
0
0
0
103
0
0
2
119
23
4
2
0
0
0
0
121
115
99
2
2
0
0
0
0
0
3
0
3
0
67
78
71
48
83
16
48
0
99
0
2
128
126
0
99
94
108
19
2
24
0
0
1
0
0
2
0
3
0
120
30
67
112
50
0
0
2
0
115
115
99
19
98
32
0
0
16
0
0
0
0
0
2
2
0
116
114
113
103
96
51
104
3
63
2
65
19
0
0
1
3
0
0
1
0
2
0
0
0
0
0
0
2
0
0
2
2
0
0
1
3
2
128
65
96
99
49
67
99
119
99
2
3
24
4
0
3
2
0
0
2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3
0
3
2
2
3
2
2
2
0
112
99
62
103
63
51
33
0
0
0
2
0
32
2
0
0
2
0
122
0
2
99
96
39
67
83
22
62
0
64
0
0
0
0
3
0
0
0
0
0
0
0
2
0
0
0
0
131
80
79
7
2
0
0
0
0
0
0
127
63
83
0
16
0
2
23
32
31
47
0
2
2
95
79
113
75
33
71
64
63
0
0
1
0
7
0
0
88
0
0
0
1
3
2
0
0
2
3
3
0
2
2
0
1
0
112
1
3
3
2
3
89
99
119
114
2
115
118
115
126
99
0
92
99
63
52
95
33
49
2
2
3
0
32
2
88
127
86
0
0
2
0
3
0
0
0
0
0
0
0
0
0
1
0
0
2
4
0
0
0
0
0
0
2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2
3
0
0
1
1
0
35
113
114
115
87
112
113
30
4
0
19
33
4
3
3
7
0
0
0
2

PLEASE HELP ME, I AM DESPERATE.

[lpcware]

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

[lpcware]

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