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@1:bf693859586c, 2017-08-21 (annotated)

Committer:
Nikollao
Date:
Mon Aug 21 11:43:03 2017 +0000
Revision:
1:bf693859586c
Parent:
0:4e20939af8bb
Child:
2:c9b24787d5e1
Fast LIA done with PIN A5 working!

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 /// make sure frequency is read before we go to the program
Nikollao 0:4e20939af8bb 13 /// cancel event-triggered rise interrupt, not to interfere with program
Nikollao 0:4e20939af8bb 14 dref.rise(NULL);
Nikollao 0:4e20939af8bb 15 pc.printf("Ref_Freq is:%.2f kHz\n\r",ref_freq*0.001);
Nikollao 1:bf693859586c 16 /// constant 6 for correct sampling time
Nikollao 1:bf693859586c 17 /// compensates for delay caused by computations
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 1:bf693859586c 24 /// find the offset of the signal
Nikollao 0:4e20939af8bb 25 offset_ticker.attach(&offset_isr,0.001);
Nikollao 0:4e20939af8bb 26
Nikollao 0:4e20939af8bb 27 while (offset == 0) {
Nikollao 0:4e20939af8bb 28 if (g_offset_flag == 1) {
Nikollao 0:4e20939af8bb 29 g_offset_flag = 0;
Nikollao 0:4e20939af8bb 30 offset = mavg_filter(filter_points);
Nikollao 0:4e20939af8bb 31 }
Nikollao 0:4e20939af8bb 32 sleep();
Nikollao 0:4e20939af8bb 33 }
Nikollao 0:4e20939af8bb 34 offset_ticker.detach();
Nikollao 1:bf693859586c 35 /// once the offset is calculated detach the offset ticker
Nikollao 1:bf693859586c 36 /// attach the output ticker to update every 1 ms
Nikollao 0:4e20939af8bb 37 output_ticker.attach(&output_isr,0.00099);
Nikollao 0:4e20939af8bb 38
Nikollao 0:4e20939af8bb 39 while (true) {
Nikollao 0:4e20939af8bb 40 // gpo = !gpo;
Nikollao 1:bf693859586c 41 digitalMix(offset); /// perform digital mixing
Nikollao 1:bf693859586c 42 while (g_output_flag == 0) {sleep();} /// sleep until flag is set
Nikollao 1:bf693859586c 43 /// update output
Nikollao 0:4e20939af8bb 44 if (g_output_flag == 1) {
Nikollao 0:4e20939af8bb 45 g_output_flag = 0;
Nikollao 0:4e20939af8bb 46 //aout = max(samples16);
Nikollao 1:bf693859586c 47 aout = 2*max(samples16);
Nikollao 1:bf693859586c 48 /// DC output by taking the maximum value of the mixed signal (R)
Nikollao 0:4e20939af8bb 49 }
Nikollao 0:4e20939af8bb 50 }
Nikollao 0:4e20939af8bb 51 }
Nikollao 0:4e20939af8bb 52
Nikollao 0:4e20939af8bb 53 double max(int points)
Nikollao 0:4e20939af8bb 54 {
Nikollao 0:4e20939af8bb 55 double amp = 0;
Nikollao 0:4e20939af8bb 56
Nikollao 0:4e20939af8bb 57 for (int i = 0; i < points; i++) {
Nikollao 0:4e20939af8bb 58 if (amp < R[i])
Nikollao 1:bf693859586c 59 amp = R[i]; /// find max of R
Nikollao 0:4e20939af8bb 60 //wait(amplitude_delay);
Nikollao 0:4e20939af8bb 61 }
Nikollao 0:4e20939af8bb 62 return amp;
Nikollao 0:4e20939af8bb 63 }
Nikollao 0:4e20939af8bb 64
Nikollao 0:4e20939af8bb 65 double mavg_filter(int filt_points)
Nikollao 0:4e20939af8bb 66 {
Nikollao 0:4e20939af8bb 67 double avg = 0, signal = 0;
Nikollao 0:4e20939af8bb 68 double delay = 0.9/(1*ref_freq*filter_points);
Nikollao 0:4e20939af8bb 69 for (int i = 0; i < filter_points; i++) {
Nikollao 0:4e20939af8bb 70 signal = ain.read();
Nikollao 0:4e20939af8bb 71 avg = avg + signal;
Nikollao 0:4e20939af8bb 72 wait((float)(5e-5));
Nikollao 0:4e20939af8bb 73 }
Nikollao 1:bf693859586c 74 avg = avg/filter_points; /// find offset of input signal
Nikollao 0:4e20939af8bb 75 return avg;
Nikollao 0:4e20939af8bb 76 }
Nikollao 0:4e20939af8bb 77
Nikollao 0:4e20939af8bb 78 void digitalMix(double remove_offset) {
Nikollao 0:4e20939af8bb 79 /// perform mixing of input and reference signals
Nikollao 0:4e20939af8bb 80 double input = 0;
Nikollao 0:4e20939af8bb 81 for (int i = 0; i < samples16;i++) {
Nikollao 0:4e20939af8bb 82 /// remove the offset before doing the multiplication of signals
Nikollao 0:4e20939af8bb 83 input = ain.read()-remove_offset;
Nikollao 0:4e20939af8bb 84 /// find the X component by multiplying with sine 17 values array
Nikollao 0:4e20939af8bb 85 double refX = input*sin_array16[i];
Nikollao 0:4e20939af8bb 86 /// find the Y component by multiplying with cosine 17 values array
Nikollao 0:4e20939af8bb 87 double refY = input*cos_array16[i];
Nikollao 0:4e20939af8bb 88 //double XY = exp(2*log(refX))+exp(2*log(refY));
Nikollao 0:4e20939af8bb 89 double XY = (refX*refX)+(refY*refY); /// R square
Nikollao 0:4e20939af8bb 90 //double R = exp(0.5*log(XY))/4;
Nikollao 0:4e20939af8bb 91 R[i] = pow(XY,0.5); /// R
Nikollao 0:4e20939af8bb 92 //aout = (1+sin_array16[i])/4;
Nikollao 0:4e20939af8bb 93 //aout = R[i]/2;
Nikollao 0:4e20939af8bb 94 wait(sample_time); /// sample time
Nikollao 0:4e20939af8bb 95 }
Nikollao 0:4e20939af8bb 96 }
Nikollao 0:4e20939af8bb 97
Nikollao 0:4e20939af8bb 98 void voltageRise() {
Nikollao 0:4e20939af8bb 99 if (g_counter == 1) {
Nikollao 0:4e20939af8bb 100 /// first time function is called is the first rise
Nikollao 0:4e20939af8bb 101 /// start timer
Nikollao 0:4e20939af8bb 102 period_timer.start();
Nikollao 0:4e20939af8bb 103 /// increase counter so next time function is called we calculate freq.
Nikollao 0:4e20939af8bb 104 g_counter++;
Nikollao 0:4e20939af8bb 105 }
Nikollao 0:4e20939af8bb 106 else if (g_counter == 2) {
Nikollao 0:4e20939af8bb 107 /// second time function is called is the second rise
Nikollao 0:4e20939af8bb 108 /// stop timer
Nikollao 0:4e20939af8bb 109 period_timer.stop();
Nikollao 0:4e20939af8bb 110 /// calculate the time taken between the two rises to find period
Nikollao 0:4e20939af8bb 111 ref_period = period_timer.read();
Nikollao 0:4e20939af8bb 112 /// frequency is the inverse of the signal period
Nikollao 0:4e20939af8bb 113 ref_freq = 1/ref_period;
Nikollao 0:4e20939af8bb 114 /// reset timer
Nikollao 0:4e20939af8bb 115 period_timer.reset();
Nikollao 0:4e20939af8bb 116 /// increase counter because we only want to calculate once per cycle
Nikollao 0:4e20939af8bb 117 /// if we want to actively track the ref_freq we should decrease counter
Nikollao 0:4e20939af8bb 118 g_counter++;
Nikollao 0:4e20939af8bb 119 }
Nikollao 0:4e20939af8bb 120 }
Nikollao 0:4e20939af8bb 121
Nikollao 0:4e20939af8bb 122 void setupK64Fclocks() {
Nikollao 0:4e20939af8bb 123 if(1) {
Nikollao 0:4e20939af8bb 124 uint32_t div1=0,div2=0,busClk=0,adcClk=0;
Nikollao 0:4e20939af8bb 125 SystemCoreClockUpdate();
Nikollao 0:4e20939af8bb 126 pc.printf("SystemCoreClock= %u \r\n",SystemCoreClock);
Nikollao 0:4e20939af8bb 127 /// System Core Clock: 120 MHz
Nikollao 0:4e20939af8bb 128 div1=( (SIM->CLKDIV1) & SIM_CLKDIV1_OUTDIV1_MASK)>>SIM_CLKDIV1_OUTDIV1_SHIFT;
Nikollao 0:4e20939af8bb 129 div1=1+div1;
Nikollao 0:4e20939af8bb 130 div2=1+( (SIM->CLKDIV1) & SIM_CLKDIV1_OUTDIV2_MASK)>>SIM_CLKDIV1_OUTDIV2_SHIFT;
Nikollao 0:4e20939af8bb 131 busClk=SystemCoreClock*div1/div2;
Nikollao 0:4e20939af8bb 132 pc.printf("Divider1== %u div2=%u \r\n",div1,div2);
Nikollao 0:4e20939af8bb 133 pc.printf("MCGOUTCLK= %u, busClk = %u \r\n",SystemCoreClock*div1,busClk);
Nikollao 0:4e20939af8bb 134 /// MCGOUTCLK 120 MHz, Bus Clock = 120 MHz
Nikollao 1:bf693859586c 135 ADC1->SC3 &= ~ADC_SC3_AVGE_MASK;//disable averages
Nikollao 1:bf693859586c 136 ADC1->CFG1 &= ~ADC_CFG1_ADLPC_MASK;//high-power mode
Nikollao 1:bf693859586c 137 ADC1->CFG1 &= ~0x0063 ; //clears ADICLK and ADIV
Nikollao 1:bf693859586c 138 ADC1->CFG1 |= ADC_CFG1_ADIV(2); //divide clock 0=/1, 1=/2, 2=/4, 3=/8
Nikollao 0:4e20939af8bb 139 //ADC0->SC3 |= 0x0007;//enable 32 averages
Nikollao 0:4e20939af8bb 140
Nikollao 1:bf693859586c 141 if (((ADC1->CFG1)& 0x03) == 0) adcClk = busClk/(0x01<<(((ADC1->CFG1)&0x60)>>5));
Nikollao 1:bf693859586c 142 if (((ADC1->SC3)& 0x04) != 0) adcClk = adcClk/(0x01<<(((ADC1->SC3)&0x03)+2));
Nikollao 0:4e20939af8bb 143 pc.printf("adcCLK= %u \r\n",adcClk);
Nikollao 0:4e20939af8bb 144 /// ADC Clock: 60 MHz
Nikollao 0:4e20939af8bb 145 }
Nikollao 0:4e20939af8bb 146 }
Nikollao 0:4e20939af8bb 147
Nikollao 0:4e20939af8bb 148 void offset_isr() {
Nikollao 0:4e20939af8bb 149 g_offset_flag = 1;
Nikollao 0:4e20939af8bb 150 }
Nikollao 0:4e20939af8bb 151
Nikollao 0:4e20939af8bb 152 void output_isr() {
Nikollao 0:4e20939af8bb 153 g_output_flag = 1;
Nikollao 0:4e20939af8bb 154 }
Nikollao 0:4e20939af8bb 155
Nikollao 0:4e20939af8bb 156 void initDAC() {
Nikollao 0:4e20939af8bb 157 DAC0->C0 = 0;
Nikollao 0:4e20939af8bb 158 DAC0->C1 = 0; //reset DAC state
Nikollao 0:4e20939af8bb 159 DAC0->C0 = DAC_C0_DACEN_MASK | DAC_C0_DACSWTRG_MASK| DAC_C0_DACRFS_MASK;
Nikollao 0:4e20939af8bb 160 }