Analog to Digital Conversion on Tiva C Series MCU

[RAKSH 1]

Here's  code performing ADC on Pin E5 on the Tiva C Series meant for struggling beginners like myself

#include <stdbool.h>
#include <stdint.h>
#include "inc/hw_memmap.h"
#include "driverlib/adc.h"
#include "driverlib/gpio.h"
#include "driverlib/sysctl.h"
#include "driverlib/adc.h"
#include "inc/hw_types.h"
#include "driverlib/debug.h"

main(void) {

uint32_t pui32ADC0Value[1];

SysCtlClockSet(SYSCTL_SYSDIV_10 | SYSCTL_USE_PLL | SYSCTL_OSC_MAIN| SYSCTL_XTAL_16MHZ);                                                                            //Set clock at 40 Mhz , Sometimes                                                                          //ADC may not work at 80Mhz 
SysCtlPeripheralEnable(SYSCTL_PERIPH_ADC0);
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOE);
ADCReferenceSet(ADC0_BASE, ADC_REF_INT); //Set reference to the internal reference
                                        // You can set it to 1V or 3 V
GPIOPinTypeADC(GPIO_PORTE_BASE, GPIO_PIN_5); //Configure GPIO as ADC

ADCSequenceDisable(ADC0_BASE, 3); //It is always a good practice to disable ADC prior                                                        //to usage ,else the ADC may not be accurate                                                               //   due to previous initializations                  
ADCSequenceConfigure(ADC0_BASE, 3, ADC_TRIGGER_PROCESSOR, 0); //Use the 3rd Sample sequencer                                                                    

ADCSequenceStepConfigure(ADC0_BASE, 3, 0,ADC_CTL_CH8 | ADC_CTL_IE | ADC_CTL_END); 
                                                         //Configure ADC to read from channel 8 ,trigger the interrupt to end data capture //          

ADCSequenceEnable(ADC0_BASE, 3);   //Enable the ADC
ADCIntClear(ADC0_BASE, 3);     //Clear interrupt to proceed to  data capture

while (1) {
ADCProcessorTrigger(ADC0_BASE, 3);   //Ask processor to trigger ADC
while (!ADCIntStatus(ADC0_BASE, 3, false))
{ //Do nothing until interrupt is triggered
}

ADCIntClear(ADC0_BASE, 3); //Clear Interrupt to proceed to next data capture                                          
ADCSequenceDataGet(ADC0_BASE, 3, pui32ADC0Value); //pui32ADC0Value is the value read                                                                     

SysCtlDelay(SysCtlClockGet() / 12);
} //Suitable delay
}

It is important to refer to datasheet before selecting the GPIO for the ADC and the channel through which it is done .
 

[rnightbane 0]

how do i test the output of this adc using matlab? does this need a USB initialization code?

[gcshyamsundhar 0]

Hi,

The sequences for initializing ADC are given beautifully in this program. I have a doubt though. In the program you have posted, you are using only ADC0 for sampling one sample from channel 8. But I need to use both the ADCs 0 and 1 for sampling. These are the connections I need to sample:

1. ADC0 samples PE1 and PE3

2. ADC1 samples PE2 and PE4.

How to configure the ADCs to sample in the above configuration ? Moreover, in one cycle I need to sample once from PE3 and PE4 and 128 times from PE1 and PE2. How can I accomplish this ?