ADC Tiva TM4c123

Hi Osama

Have you tried to connect the sensor and see if works fine?
The same happens to me with the TM4C129x, if I leave the pins floating there was a voltage read by the ADC. I was a little surprise so I read the voltage in the floating pins with a multimeter and there was a voltage about 1V or more (I don't know yet if that is normal, I'm investigating) but then I put a voltage on the pin and the ADC read it perfectly so the ADC works fine.

Regards, Juan.

Hello All,

Do not leave Analog pins for ADC floating. It is easy place for cross talk.

Thanks 4 ur reply.Here in the code I am saving he value of 2nd sensor to puivalADC0[1].If I did this the same problem arises but If i save the value to 3rd place in fifo puivalADC0[3] than the problem doesnt occur.Shouldnt it be saved in 2nd place in fifo as it is the value from 2nd channel??

Hello All,

The ADC interrupt status is asserted when the conversion is complete. On completion there should be only 2 read from the FIFO, otherwise it may create the situation of FIFO underflow.

yup but from which one as i said from ulADC0value[0] and ulADC0value[1] or from ulADC0value[0] and ulADC0value[3] ??

Hello All,

It should be 0 and 1 as there are only 2 values to read.

Is this code correct??I am using 2 potentiometers for sending analog data.But one sensor reading is replicating on fifo1 also.In the code I am saving the result of 0 and 1 values to int a and b but its not working .But if I saved the values of 0 and 3 to int a and b then its woking fine.But 0 and 1 should be the values.I am bit confused.Kindly check the code thoroughly

#include <stdio.h>
#include <string.h>
#include <stdint.h>
#include <stdbool.h>
#include "inc/hw_ints.h"
#include "inc/hw_memmap.h"
#include "driverlib/debug.h"
#include "driverlib/fpu.h"
#include "driverlib/gpio.h"
#include "driverlib/interrupt.h"
#include "driverlib/pin_map.h"
#include "driverlib/rom.h"
#include "driverlib/sysctl.h"
#include "driverlib/uart.h"
#include <string.h>
#include <stdlib.h>
#include "driverlib/systick.h"
#include "inc/hw_nvic.h"
#include "driverlib/adc.h"
//#include "tm4c123gh6pm.h"
#include "buffer.h"
#include "utils/uartstdio.h"
#include "utils/uartstdio.c"
#include "data_n_math.h"
#include "lib_parse.h"
#include "lcd4d_lib.h"
#include "error_misc.h"
#include "Misc_Config.h"

int main()

{

uint32_t pui32ADC0Value[4];
ROM_FPUEnable();
ROM_FPULazyStackingEnable();
// ROM_SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC | SYSCTL_OSC_MAIN |SYSCTL_XTAL_16MHZ);
//SEt CLOCK TO 80MHZ
ROM_SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC | SYSCTL_OSC_MAIN |SYSCTL_XTAL_16MHZ|SYSCTL_SYSDIV_2_5);

SysCtlPeripheralEnable(SYSCTL_PERIPH_ADC0); //ADC0 on
GPIOPinTypeADC(GPIO_PORTE_BASE, GPIO_PIN_2);
GPIOPinTypeADC(GPIO_PORTE_BASE, GPIO_PIN_1);
//ADC0 sequencer 1 stepconfiguration meaning which fifo to which input chanel
ADCSequenceConfigure(ADC0_BASE, 1, ADC_TRIGGER_PROCESSOR, 0);//ADC0 sequencer 1 with 4 fifo so it can sample 4 inputs from 4 different chanels
ADCSequenceStepConfigure(ADC0_BASE, 1, 0, ADC_CTL_CH1);//(ADC),Sequencer1,fifo0,ADC chanel 1(PE2)
ADCSequenceStepConfigure(ADC0_BASE, 1, 1, ADC_CTL_CH2| ADC_CTL_IE |ADC_CTL_END);
//ADCHardwareOversampleConfigure(ADC0_BASE,64);
ADCSequenceEnable(ADC0_BASE, 1);
ADCIntClear(ADC0_BASE, 1);

while(1)

{

ADCProcessorTrigger(ADC0_BASE, 1);
while(!ADCIntStatus(ADC0_BASE, 1, false))
{
}
ADCIntClear(ADC0_BASE, 1);
ADCSequenceDataGet(ADC0_BASE, 1, pui32ADC0Value)

}
int a=pui32ADC0Value[0];
int b=pui32ADC0Value[1];
}

Hello All,

Try the following

SysCtlPeripheralDisable(SYSCTL_PERIPH_ADC0)
SysCtlPeripheralReset(SYSCTL_PERIPH_ADC0)
SysCtlPeripheralEnable(SYSCTL_PERIPH_ADC0)

Instead of just

SysCtlPeripheralEnable(SYSCTL_PERIPH_ADC0)

I think the FIFO flags are lost.

Its not working.Still the values are overlapping.The value of channel 0 also copies on channel 1 by moving knob of potentio attach to channel 0 where as moving knob of potentio 1 doesnt do anything to value of channel 1

Hello All

If you connect Channel 1 to GND and then check does it give the value of ~0?

No its still giving the replicated value of channel 0

In addition to Amit's suggestion.

What value are your pots?

How are you connecting them to the A/D input?

Robert

Hello All,

It seems that for some reason channel 1 is not connected to channel 1 but to channel 0. Did you check the connection/soldering?

No Sir!!They are not short.Sir the point is where to extract the data??If I extract from fifo position 4 than channel 1 and channel 2 are giving correct values but theoretically the values should be extracted form fifo 0 and fifo 1 which is replicating .

Pot can be used to send analog values

Hello All,

Where is the clock for the GPIO Port E peripheral being enabled?

Isn't the clock is default set to 125ksps unless u set it??So I keep that to default

Hello All,

It would be 1MSPS. Please check the register ADCPC for the configuration of the sampling rate.

Yes, but what is the value of the pot? And how are you connecting it?

Robert