Hi All.
We have written the simplest of code (hopefully), trying to read a ADC value on a TM4C1230D5PM.
However, the code does not work (always shows values from 1405-1409, irrespective of whether the analog-voltage source is on/off, or the value of analog-voltage when the analog-voltage source is on).
#include <stdbool.h> #include <stdint.h> #include "inc/hw_memmap.h" #include "driverlib/adc.h" #include "driverlib/gpio.h" #include "driverlib/pin_map.h" #include "driverlib/sysctl.h" #include "driverlib/uart.h" #include "utils/uartstdio.h" uint32_t pui32ADC0Value[1]; void adc_initialize(void) { /* * Set the clocking to run directly from the crystal. */ ROM_SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC | SYSCTL_OSC_MAIN | SYSCTL_XTAL_16MHZ); // // The ADC0 peripheral must be enabled for use. // SysCtlPeripheralEnable(SYSCTL_PERIPH_ADC0); // // For this example ADC0 is used with AIN0 on port E7. // The actual port and pins used may be different on your part, consult // the data sheet for more information. GPIO port E needs to be enabled // so these pins can be used. // TODO: change this to whichever GPIO port you are using. // SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOE); // // Select the analog ADC function for these pins. // Consult the data sheet to see which functions are allocated per pin. // TODO: change this to select the port/pin you are using. // GPIOPinTypeADC(GPIO_PORTE_BASE, GPIO_PIN_1); // // Enable sample sequence 3 with a processor signal trigger. Sequence 3 // will do a single sample when the processor sends a signal to start the // conversion. Each ADC module has 4 programmable sequences, sequence 0 // to sequence 3. This example is arbitrarily using sequence 3. // ADCSequenceConfigure(ADC0_BASE, 3, ADC_TRIGGER_PROCESSOR, 0); // // Configure step 0 on sequence 3. Sample channel 0 (ADC_CTL_CH0) in // single-ended mode (default) and configure the interrupt flag // (ADC_CTL_IE) to be set when the sample is done. Tell the ADC logic // that this is the last conversion on sequence 3 (ADC_CTL_END). Sequence // 3 has only one programmable step. Sequence 1 and 2 have 4 steps, and // sequence 0 has 8 programmable steps. Since we are only doing a single // conversion using sequence 3 we will only configure step 0. For more // information on the ADC sequences and steps, reference the datasheet. // ADCSequenceStepConfigure(ADC0_BASE, 3, 0, ADC_CTL_CH0 | ADC_CTL_IE | ADC_CTL_END); // // Since sample sequence 3 is now configured, it must be enabled. // ADCSequenceEnable(ADC0_BASE, 3); // // Clear the interrupt status flag. This is done to make sure the // interrupt flag is cleared before we sample. // ADCIntClear(ADC0_BASE, 3); } void process() { // // Sample AIN0. // if(1) { // // Trigger the ADC conversion. // ADCProcessorTrigger(ADC0_BASE, 3); // // Wait for conversion to be completed. // while(!ADCIntStatus(ADC0_BASE, 3, false)) { } // // Clear the ADC interrupt flag. // ADCIntClear(ADC0_BASE, 3); // // Read ADC Value. // ADCSequenceDataGet(ADC0_BASE, 3, pui32ADC0Value); // // Display the AIN0 (PE7) digital value on the console. // info_log("AIN0 = %u", pui32ADC0Value[0]); } } int main(int argc, char** argv) { /* * All application-specific logger/timer initialization */ adc_initialize(); info_log("INIT done"); while(1) { startAndCountdownTimer(1, 0); process(); } return 0; }
The above code has been picked up from the example single-ended ADC example from the gcc-toolchain.
Kindly provide pointers on what is missing.
We will be grateful.
Thanks and Regards,
Ajay