Nikollao Sulollari / Mbed 2 deprecated Fast_LIA_final

The project is a fast lock in amplifier (LIA) which can update its output at rate of 1000 measurements/s. It performs digital dual mixing and filtering to obtain a DC value proportional to the AC input signal.

Dependencies:   N5110 mbed

main.cpp@0:4e20939af8bb, 2017-08-21 (annotated)

Committer:
Nikollao
Date:
Mon Aug 21 11:22:14 2017 +0000
Revision:
0:4e20939af8bb
Child:
1:bf693859586c
LIA FAST DONE!

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Nikollao 0:4e20939af8bb 1 #include "main.h"
Nikollao 0:4e20939af8bb 2
Nikollao 0:4e20939af8bb 3 int main()
Nikollao 0:4e20939af8bb 4 {
Nikollao 0:4e20939af8bb 5 pc.baud(115200);
Nikollao 0:4e20939af8bb 6 dref.rise(&voltageRise); /// set interrupt to calculate reference frequency
Nikollao 0:4e20939af8bb 7 setupK64Fclocks();
Nikollao 0:4e20939af8bb 8 /// initialise DAC output dac0_out
Nikollao 0:4e20939af8bb 9 while (ref_freq < 1e2) {
Nikollao 0:4e20939af8bb 10 sleep();
Nikollao 0:4e20939af8bb 11 }
Nikollao 0:4e20939af8bb 12 //ref_freq = 5e3;
Nikollao 0:4e20939af8bb 13 /// make sure frequency is read before we go to the program
Nikollao 0:4e20939af8bb 14 /// cancel event-triggered rise interrupt, not to interfere with program
Nikollao 0:4e20939af8bb 15 dref.rise(NULL);
Nikollao 0:4e20939af8bb 16 pc.printf("Ref_Freq is:%.2f kHz\n\r",ref_freq*0.001);
Nikollao 0:4e20939af8bb 17 //constant
Nikollao 0:4e20939af8bb 18 sample_freq = 6*samples16*ref_freq;
Nikollao 0:4e20939af8bb 19 sample_time = 1/sample_freq;
Nikollao 0:4e20939af8bb 20
Nikollao 0:4e20939af8bb 21 initDAC();
Nikollao 0:4e20939af8bb 22 delay_freq = ref_freq*amp_points;
Nikollao 0:4e20939af8bb 23 amplitude_delay = 1/delay_freq;
Nikollao 0:4e20939af8bb 24 offset_ticker.attach(&offset_isr,0.001);
Nikollao 0:4e20939af8bb 25
Nikollao 0:4e20939af8bb 26 while (offset == 0) {
Nikollao 0:4e20939af8bb 27 if (g_offset_flag == 1) {
Nikollao 0:4e20939af8bb 28 g_offset_flag = 0;
Nikollao 0:4e20939af8bb 29 offset = mavg_filter(filter_points);
Nikollao 0:4e20939af8bb 30 }
Nikollao 0:4e20939af8bb 31 sleep();
Nikollao 0:4e20939af8bb 32 }
Nikollao 0:4e20939af8bb 33 offset_ticker.detach();
Nikollao 0:4e20939af8bb 34
Nikollao 0:4e20939af8bb 35 output_ticker.attach(&output_isr,0.00099);
Nikollao 0:4e20939af8bb 36
Nikollao 0:4e20939af8bb 37 while (true) {
Nikollao 0:4e20939af8bb 38 // gpo = !gpo;
Nikollao 0:4e20939af8bb 39 digitalMix(offset);
Nikollao 0:4e20939af8bb 40 while (g_output_flag == 0) {sleep();}
Nikollao 0:4e20939af8bb 41
Nikollao 0:4e20939af8bb 42 if (g_output_flag == 1) {
Nikollao 0:4e20939af8bb 43 g_output_flag = 0;
Nikollao 0:4e20939af8bb 44 //aout = max(samples16);
Nikollao 0:4e20939af8bb 45 aout = 2*max(samples16);
Nikollao 0:4e20939af8bb 46 }
Nikollao 0:4e20939af8bb 47 }
Nikollao 0:4e20939af8bb 48 }
Nikollao 0:4e20939af8bb 49
Nikollao 0:4e20939af8bb 50 double max(int points)
Nikollao 0:4e20939af8bb 51 {
Nikollao 0:4e20939af8bb 52 double amp = 0;
Nikollao 0:4e20939af8bb 53
Nikollao 0:4e20939af8bb 54 for (int i = 0; i < points; i++) {
Nikollao 0:4e20939af8bb 55 if (amp < R[i])
Nikollao 0:4e20939af8bb 56 amp = R[i];
Nikollao 0:4e20939af8bb 57 //wait(amplitude_delay);
Nikollao 0:4e20939af8bb 58 }
Nikollao 0:4e20939af8bb 59 return amp;
Nikollao 0:4e20939af8bb 60 }
Nikollao 0:4e20939af8bb 61
Nikollao 0:4e20939af8bb 62 double mavg_filter(int filt_points)
Nikollao 0:4e20939af8bb 63 {
Nikollao 0:4e20939af8bb 64 double avg = 0, signal = 0;
Nikollao 0:4e20939af8bb 65 double delay = 0.9/(1*ref_freq*filter_points);
Nikollao 0:4e20939af8bb 66 for (int i = 0; i < filter_points; i++) {
Nikollao 0:4e20939af8bb 67 signal = ain.read();
Nikollao 0:4e20939af8bb 68 avg = avg + signal;
Nikollao 0:4e20939af8bb 69 wait((float)(5e-5));
Nikollao 0:4e20939af8bb 70 }
Nikollao 0:4e20939af8bb 71 avg = avg/filter_points;
Nikollao 0:4e20939af8bb 72 return avg;
Nikollao 0:4e20939af8bb 73 }
Nikollao 0:4e20939af8bb 74
Nikollao 0:4e20939af8bb 75 void digitalMix(double remove_offset) {
Nikollao 0:4e20939af8bb 76 /// perform mixing of input and reference signals
Nikollao 0:4e20939af8bb 77 double input = 0;
Nikollao 0:4e20939af8bb 78 for (int i = 0; i < samples16;i++) {
Nikollao 0:4e20939af8bb 79 /// remove the offset before doing the multiplication of signals
Nikollao 0:4e20939af8bb 80 input = ain.read()-remove_offset;
Nikollao 0:4e20939af8bb 81 /// find the X component by multiplying with sine 17 values array
Nikollao 0:4e20939af8bb 82 double refX = input*sin_array16[i];
Nikollao 0:4e20939af8bb 83 /// find the Y component by multiplying with cosine 17 values array
Nikollao 0:4e20939af8bb 84 double refY = input*cos_array16[i];
Nikollao 0:4e20939af8bb 85 //double XY = exp(2*log(refX))+exp(2*log(refY));
Nikollao 0:4e20939af8bb 86 double XY = (refX*refX)+(refY*refY); /// R square
Nikollao 0:4e20939af8bb 87 //double R = exp(0.5*log(XY))/4;
Nikollao 0:4e20939af8bb 88 R[i] = pow(XY,0.5); /// R
Nikollao 0:4e20939af8bb 89 //aout = (1+sin_array16[i])/4;
Nikollao 0:4e20939af8bb 90 //aout = R[i]/2;
Nikollao 0:4e20939af8bb 91 wait(sample_time); /// sample time
Nikollao 0:4e20939af8bb 92 }
Nikollao 0:4e20939af8bb 93 }
Nikollao 0:4e20939af8bb 94
Nikollao 0:4e20939af8bb 95 void voltageRise() {
Nikollao 0:4e20939af8bb 96 if (g_counter == 1) {
Nikollao 0:4e20939af8bb 97 /// first time function is called is the first rise
Nikollao 0:4e20939af8bb 98 /// start timer
Nikollao 0:4e20939af8bb 99 period_timer.start();
Nikollao 0:4e20939af8bb 100 /// increase counter so next time function is called we calculate freq.
Nikollao 0:4e20939af8bb 101 g_counter++;
Nikollao 0:4e20939af8bb 102 }
Nikollao 0:4e20939af8bb 103 else if (g_counter == 2) {
Nikollao 0:4e20939af8bb 104 /// second time function is called is the second rise
Nikollao 0:4e20939af8bb 105 /// stop timer
Nikollao 0:4e20939af8bb 106 period_timer.stop();
Nikollao 0:4e20939af8bb 107 /// calculate the time taken between the two rises to find period
Nikollao 0:4e20939af8bb 108 ref_period = period_timer.read();
Nikollao 0:4e20939af8bb 109 /// frequency is the inverse of the signal period
Nikollao 0:4e20939af8bb 110 ref_freq = 1/ref_period;
Nikollao 0:4e20939af8bb 111 /// reset timer
Nikollao 0:4e20939af8bb 112 period_timer.reset();
Nikollao 0:4e20939af8bb 113 /// increase counter because we only want to calculate once per cycle
Nikollao 0:4e20939af8bb 114 /// if we want to actively track the ref_freq we should decrease counter
Nikollao 0:4e20939af8bb 115 g_counter++;
Nikollao 0:4e20939af8bb 116 }
Nikollao 0:4e20939af8bb 117 }
Nikollao 0:4e20939af8bb 118
Nikollao 0:4e20939af8bb 119 void setupK64Fclocks() {
Nikollao 0:4e20939af8bb 120 if(1) {
Nikollao 0:4e20939af8bb 121 uint32_t div1=0,div2=0,busClk=0,adcClk=0;
Nikollao 0:4e20939af8bb 122 SystemCoreClockUpdate();
Nikollao 0:4e20939af8bb 123 pc.printf("SystemCoreClock= %u \r\n",SystemCoreClock);
Nikollao 0:4e20939af8bb 124 /// System Core Clock: 120 MHz
Nikollao 0:4e20939af8bb 125 div1=( (SIM->CLKDIV1) & SIM_CLKDIV1_OUTDIV1_MASK)>>SIM_CLKDIV1_OUTDIV1_SHIFT;
Nikollao 0:4e20939af8bb 126 div1=1+div1;
Nikollao 0:4e20939af8bb 127 div2=1+( (SIM->CLKDIV1) & SIM_CLKDIV1_OUTDIV2_MASK)>>SIM_CLKDIV1_OUTDIV2_SHIFT;
Nikollao 0:4e20939af8bb 128 busClk=SystemCoreClock*div1/div2;
Nikollao 0:4e20939af8bb 129 pc.printf("Divider1== %u div2=%u \r\n",div1,div2);
Nikollao 0:4e20939af8bb 130 pc.printf("MCGOUTCLK= %u, busClk = %u \r\n",SystemCoreClock*div1,busClk);
Nikollao 0:4e20939af8bb 131 /// MCGOUTCLK 120 MHz, Bus Clock = 120 MHz
Nikollao 0:4e20939af8bb 132 ADC0->SC3 &= ~ADC_SC3_AVGE_MASK;//disable averages
Nikollao 0:4e20939af8bb 133 ADC0->CFG1 &= ~ADC_CFG1_ADLPC_MASK;//high-power mode
Nikollao 0:4e20939af8bb 134 ADC0->CFG1 &= ~0x0063 ; //clears ADICLK and ADIV
Nikollao 0:4e20939af8bb 135 ADC0->CFG1 |= ADC_CFG1_ADIV(2); //divide clock 0=/1, 1=/2, 2=/4, 3=/8
Nikollao 0:4e20939af8bb 136 //ADC0->SC3 |= 0x0007;//enable 32 averages
Nikollao 0:4e20939af8bb 137
Nikollao 0:4e20939af8bb 138 if (((ADC0->CFG1)& 0x03) == 0) adcClk = busClk/(0x01<<(((ADC0->CFG1)&0x60)>>5));
Nikollao 0:4e20939af8bb 139 if (((ADC0->SC3)& 0x04) != 0) adcClk = adcClk/(0x01<<(((ADC0->SC3)&0x03)+2));
Nikollao 0:4e20939af8bb 140 pc.printf("adcCLK= %u \r\n",adcClk);
Nikollao 0:4e20939af8bb 141 /// ADC Clock: 60 MHz
Nikollao 0:4e20939af8bb 142 }
Nikollao 0:4e20939af8bb 143 }
Nikollao 0:4e20939af8bb 144
Nikollao 0:4e20939af8bb 145 void offset_isr() {
Nikollao 0:4e20939af8bb 146 g_offset_flag = 1;
Nikollao 0:4e20939af8bb 147 }
Nikollao 0:4e20939af8bb 148
Nikollao 0:4e20939af8bb 149 void output_isr() {
Nikollao 0:4e20939af8bb 150 g_output_flag = 1;
Nikollao 0:4e20939af8bb 151 }
Nikollao 0:4e20939af8bb 152
Nikollao 0:4e20939af8bb 153 void initDAC() {
Nikollao 0:4e20939af8bb 154 DAC0->C0 = 0;
Nikollao 0:4e20939af8bb 155 DAC0->C1 = 0; //reset DAC state
Nikollao 0:4e20939af8bb 156 DAC0->C0 = DAC_C0_DACEN_MASK | DAC_C0_DACSWTRG_MASK| DAC_C0_DACRFS_MASK;
Nikollao 0:4e20939af8bb 157 }