ADC output

Hello M. Mary,

Channel 8 is not PE1 or PE2. It is PE5. So you would need to correct the channel mapping

Please have a look at the ADC Chapter of the Data Sheet for Signal Description. The Column "Pin Name" has the analog channel and Pin Mux/Assignment of which Physical Port-Pin it maps to

Regards

Amit

Thank you Amit.

I try to configure a simple program to get external input from PE5 by referring ADC chapter . But that also produces same 0 output. I don't know what is the problem.The code is,

#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);                                                                          
SysCtlPeripheralEnable(SYSCTL_PERIPH_ADC0);
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOE);

GPIOPinTypeADC(GPIO_PORTE_BASE, GPIO_PIN_5);
GPIOPinTypeGPIOInput(GPIO_PORTE_BASE, GPIO_PIN_5);
GPIODirModeSet(GPIO_PORTE_BASE, GPIO_PIN_5,GPIO_DIR_MODE_IN);                           
GPIOIntEnable(GPIO_PORTE_BASE, GPIO_PIN_5);

ADCIntEnable(ADC0_BASE, 3);
ADCSequenceDisable(ADC0_BASE, 3);
ADCSequenceConfigure(ADC0_BASE, 3, ADC_TRIGGER_PROCESSOR, 0);
ADCSequenceStepConfigure(ADC0_BASE, 3, 0,ADC_CTL_CH8 | ADC_CTL_IE | ADC_CTL_END);
                                                   

ADCSequenceEnable(ADC0_BASE, 3);
while (1) {
ADCProcessorTrigger(ADC0_BASE, 3);  
while (!ADCIntStatus(ADC0_BASE, 3, false))
{
}

ADCIntClear(ADC0_BASE, 3);
ADCSequenceDataGet(ADC0_BASE, 3, pui32ADC0Value);
SysCtlDelay(SysCtlClockGet() / 12);
}

}

Hello M. Mary,

The GPIO Configuration needed an update. Other than that I ran the code and tested it for +3.3V and 0V and it gives the correct code, when the voltage is applied on PE5 pin.

main(void) {

    uint32_t pui32ADC0Value[1];

    SysCtlClockSet(SYSCTL_SYSDIV_10 | SYSCTL_USE_PLL | SYSCTL_OSC_MAIN| SYSCTL_XTAL_16MHZ);
    SysCtlPeripheralEnable(SYSCTL_PERIPH_ADC0);
    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOE);


    GPIOPinTypeADC(GPIO_PORTE_BASE, GPIO_PIN_5);

    ADCIntEnable(ADC0_BASE, 3);
    ADCSequenceDisable(ADC0_BASE, 3);
    ADCSequenceConfigure(ADC0_BASE, 3, ADC_TRIGGER_PROCESSOR, 0);
    ADCSequenceStepConfigure(ADC0_BASE, 3, 0,ADC_CTL_CH8 | ADC_CTL_IE | ADC_CTL_END);


    ADCSequenceEnable(ADC0_BASE, 3);
    while (1) {
        ADCProcessorTrigger(ADC0_BASE, 3);
        while (!ADCIntStatus(ADC0_BASE, 3, false))
        {
        }

        ADCIntClear(ADC0_BASE, 3);
        ADCSequenceDataGet(ADC0_BASE, 3, pui32ADC0Value);
        SysCtlDelay(SysCtlClockGet() / 12);
    }

}

Regards

Amit

Before searching for problems in the code, confirm the expected voltage at the ADC input pin of the MCU, and I mean the MCU pin (or at least as close as possible).

the following code produce 0 output value from function generator which is set for 5.

I hope that does not mean 5V.

HI Amit,

Thank you.

I think I made mistake while testing. Can you tell me how i can test for external input?

Hello M Mary,

If you are using the EK-TM4C123, then connect the Pin to the +3.3V header and/or GND to see that the conversion happens as per the analog input on the pin.

Regards

Amit

Thank you Amit,

I checked that by connecting PE5 to 3.3v header in J1 row. Then given input from function generator to PE5 pin and Gnd in J3 row. But i got 3900,3906... like values. What is wrong? any other hardware connections missed by me?

Hi Mary,

So when you connected it to the 3.3V it was all alright?

Only the fuction generator gave those values?

Hi Luis,

I check ADC with   the program posted by Amit. That is

#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);
    SysCtlPeripheralEnable(SYSCTL_PERIPH_ADC0);
    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOE);

    GPIOPinTypeADC(GPIO_PORTE_BASE, GPIO_PIN_5);

    ADCIntEnable(ADC0_BASE, 3);
    ADCSequenceDisable(ADC0_BASE, 3);
    ADCSequenceConfigure(ADC0_BASE, 3, ADC_TRIGGER_PROCESSOR, 0);
    ADCSequenceStepConfigure(ADC0_BASE, 3, 0,ADC_CTL_CH8 | ADC_CTL_IE | ADC_CTL_END);


    ADCSequenceEnable(ADC0_BASE, 3);
    while (1) {
        ADCProcessorTrigger(ADC0_BASE, 3);
        while (!ADCIntStatus(ADC0_BASE, 3, false))
        {
        }

        ADCIntClear(ADC0_BASE, 3);
        ADCSequenceDataGet(ADC0_BASE, 3, pui32ADC0Value);
        SysCtlDelay(SysCtlClockGet() / 12);
    }

}

Initially I check the output without giving input from function generator and all for some clarifications. That produces output as 2839,2838.... Then I give input from FG with  settings: freq=50Hz and 3.0v. And 3.3v header is connected to PE5 pin. Now I got 2837,2830... like values. These values are the  pui32ADC0Value values. I dont know what is the problem.

Hi Mary,

without notigh connected the pin is floating and any value can apear.

You should connect only the MCU 3.3V with a resistor to that pin and see what values it gives.

The fuction generator is making a analog wave right? Well then depending on what part of the wave the ADC is fired any value can apear since the wave would go from 0 to 3V. If you have the 3.3V header conected at the same time as the FG of course it will give weird values.

I belive Amit sugested conecting PE5 to 3.3V or GND just to test if the ADC was working since it would give a value arround 4095 (3.3V) and 0(GND). Am i correct @Amit Ashara ? (does mention user work here?)

Thank you all.

Now i get understand the process in ADC. Thank you so much.

Hello Luis

Yes, your point is correct. the Test rig I proposed for the LaunchPad is the simplest method of making sure it works as expected before connecting an Analog Signal

Regards

Amit