How to use ADC module to measure external voltage

Einswell

How to use ADC module to measure external voltage [Copy link]

I am using the tiva c TM4C123GH6PM board, and now I want to use the ADC module to measure the external DC voltage. Then I use the PD0 pin to connect the external voltage value to be measured, and then connect the GND pin to the ground of the circuit to be measured. But I can't measure the value. Even if I change the external voltage, the measured value of the ADC module is always a fixed value. The main program is as follows. I hope you can help! ! #include
#include
#include
#include
#include
#include "inc/hw_memmap.h" #include "inc/hw_types.h" #include "inc/hw_ints.h" #include "inc/hw_gpio.h" #include "inc/hw_sysctl.h" #include "inc/ hw_adc.h" #include "driverlib/adc.h" #include "driverlib/interrupt.h" #include "driverlib/sysctl.h" #include "driverlib/systick.h" #include "driverlib/gpio.h" #include "driverlib/pin_map.h" #include "driverlib/rom.h" #include "driverlib/ssi. h" #include "uc1701.h" //ADC initializer void ADC_Init() { SysCtlPeripheralEnable(SYSCTL_PERIPH_ADC0); SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOD); GPIOPinTypeGPIOInput(GPIO_PORTD_BASE, GPIO_PIN_0); GPIOPinTypeADC(GPIO_PORTD_BASE, GPIO_PIN_0); ADCSequenceConfigure(ADC0_BASE,1,ADC_TRIGGER_PROCESSOR, 0); ADCSequenceStepConfigure(ADC0_BASE, 1, 0, ADC_CTL_CH0); ADCSequenceStepConfigure(ADC0_BASE, 1, 1, ADC_CTL_CH0); ADCSequenceStepConfigure(ADC0_BASE, 1, 2, ADC_CTL_CH0); ADCSequenceStepConfigure(ADC0_BASE,1,3,ADC_CTL_CH0|ADC_CTL_IE|ADC_CTL_END); ADCSequenceEnable(ADC0_BASE, 1); } uint32_t ui32ADC0Value[4]; uint32_t num0; int main() { SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC | SYSCTL_OSC_MAIN | SYSCTL_XTAL_16MHZ); ADC_Init(); UC1701Init(60000); UC1701Clear(); while(1) { UC1701CharDispaly(0, 1, "I love tiva-pb?"); ADCIntClear(ADC0_BASE, 1); ADCProcessorTrigger(ADC0_BASE, 1); while(!ADCIntStatus(ADC0_BASE, 1, false)) { } ADCSequenceDataGet(ADC0_BASE, 1, ui32ADC0Value); num0 = (ui32ADC0Value[0] + ui32ADC0Value[1] + ui32ADC0Value[2] + ui32ADC0Value[3] + 2)/4; UC1701DisplayN(1,1,num0); UC1701Clear(); } } [ size=5]

fzpfzp

As for the circuit, there may be something wrong with your circuit itself.

littleshrimp

It should be a code problem. Try using TI's official ADC routine first. Do not measure the external voltage first. Try connecting the ADC input pin to GND or the MCU power supply to see if there is any change. After it is adjusted, measure the external voltage again.

Jacktang

The TM4C123GH6PM circuit diagram is not posted, so it is difficult to judge. There are many circuit problems.

tiankai001

The third post has the correct answer. Try using the official routine first. If the official routine can measure the voltage correctly, it means there is something wrong with the program.