91 lines
3.2 KiB
C
91 lines
3.2 KiB
C
#include <stdint.h>
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#include <stdbool.h>
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#include "inc/tm4c1294ncpdt.h"
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#include "driverlib/adc.h"
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#include "driverlib/pin_map.h"
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#include "driverlib/gpio.h"
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#include "driverlib/sysctl.h"
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#include "driverlib/interrupt.h"
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#include "driverlib/timer.h"
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#include "sysctl_pll.h"
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#include "inc/hw_types.h"
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#include "inc/hw_memmap.h"
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#include <math.h>
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#include "buttons.h"
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#include "sampling.h"
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extern uint32_t gSystemClock; // [Hz] system clock frequency
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// latest sample index
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void ADC_ISR(void)
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{
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// clear ADC1 sequence0 interrupt flag in the ADCISC register
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//HWREGBITW(ADC1_ISC_R, 1) = 1;
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ADC1_ISC_R |= 1;
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// check for ADC FIFO overflow
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if(ADC1_OSTAT_R & ADC_OSTAT_OV0) {
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gADCErrors++; // count errors
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ADC1_OSTAT_R = ADC_OSTAT_OV0; // clear overflow condition
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}
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gADCBufferIndex = ADC_BUFFER_WRAP(gADCBufferIndex + 1);
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// read sample from the ADC1 sequence 0 FIFO
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gADCBuffer[gADCBufferIndex] = (ADC1_SSFIFO0_R & ADC_SSFIFO0_DATA_M);
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}
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void start_sampler() {
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gADCBufferIndex = ADC_BUFFER_SIZE - 1;
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gADCErrors = 0;
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SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOE);
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GPIOPinTypeADC(GPIO_PORTE_BASE,
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GPIO_PIN_0); // GPIO setup for analog input AIN3
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// initialize ADC peripherals
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SysCtlPeripheralEnable(SYSCTL_PERIPH_ADC0);
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SysCtlPeripheralEnable(SYSCTL_PERIPH_ADC1);
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// timer for low-speed
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SysCtlPeripheralEnable(SYSCTL_PERIPH_TIMER2);
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// ADC clock
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uint32_t pll_frequency = SysCtlFrequencyGet(CRYSTAL_FREQUENCY);
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uint32_t pll_divisor =
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(pll_frequency - 1) / (16 * ADC_SAMPLING_RATE) + 1; // round up
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ADCClockConfigSet(ADC0_BASE, ADC_CLOCK_SRC_PLL | ADC_CLOCK_RATE_FULL,
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pll_divisor);
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ADCClockConfigSet(ADC1_BASE, ADC_CLOCK_SRC_PLL | ADC_CLOCK_RATE_FULL,
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pll_divisor);
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// choose ADC1 sequence 0; disable before configuring
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ADCSequenceDisable(ADC1_BASE, 0);
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ADCSequenceConfigure(ADC1_BASE, 0, ADC_TRIGGER_ALWAYS,
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0); // specify the "Always" trigger
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// in the 0th step, sample channel 3 (AIN3)
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// enable interrupt, and make it the end of sequence
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ADCSequenceStepConfigure(ADC1_BASE, 0, 0, ADC_CTL_CH3 | ADC_CTL_END | ADC_CTL_IE);
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// enable the sequence. it is now sampling
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ADCSequenceEnable(ADC1_BASE, 0);
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// enable sequence 0 interrupt in the ADC1 peripheral
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ADCIntEnable(ADC1_BASE, 0); // INT_ADC1SS0
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}
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void set_frequency(uint64_t microseconds) {
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if (microseconds == 1) {
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ADCSequenceDisable(ADC1_BASE, 0);
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// don't use a timer for high speed
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ADCSequenceConfigure(ADC1_BASE, 0, ADC_TRIGGER_ALWAYS, 0);
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ADCSequenceEnable(ADC1_BASE, 0);
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return;
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}
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// initialize timer 2 in periodic mode
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TimerDisable(TIMER2_BASE, TIMER_BOTH);
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TimerConfigure(TIMER2_BASE, TIMER_CFG_PERIODIC);
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#define MICROSECONDS_PER_SECOND 1000000
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TimerLoadSet(TIMER2_BASE, TIMER_A, (uint32_t) ((uint64_t) gSystemClock * microseconds / MICROSECONDS_PER_SECOND) - 1);
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TimerControlTrigger(TIMER2_BASE, TIMER_A, true);
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TimerEnable(TIMER2_BASE, TIMER_A);
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ADCSequenceDisable(ADC1_BASE, 0);
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ADCSequenceConfigure(ADC1_BASE, 0, ADC_TRIGGER_TIMER, 0);
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ADCSequenceEnable(ADC1_BASE, 0);
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}
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