/
teensy_histogram_measure_ADC.ino
260 lines (208 loc) · 8.69 KB
/
teensy_histogram_measure_ADC.ino
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
#include <ADC.h>
#include <ADC_util.h>
ADC *adc = new ADC(); // adc object
const uint32_t analogReadBitDepth0 = 12;
const uint32_t analogReadBitDepth1 = 12;
const uint32_t analogReadMax0 = (1 << analogReadBitDepth0);
const uint32_t analogReadMax1 = (1 << analogReadBitDepth1);
const uint32_t analogReadAveragingNum0 = 32;
const uint32_t analogReadAveragingNum1 = 32;
const uint32_t analogReadPin0 = A0; // ADC0 or ADC1
const uint32_t analogReadPin1 = A1; // ADC0 or ADC1
const enum ADC_settings::ADC_CONVERSION_SPEED conversionSpeeds[2] = {ADC_CONVERSION_SPEED::VERY_HIGH_SPEED, ADC_CONVERSION_SPEED::VERY_HIGH_SPEED};
/* For Teensy 4:
VERY_LOW_SPEED: is the lowest possible sampling speed (+22 ADCK, 24 in total).
LOW_SPEED adds +18 ADCK, 20 in total.
LOW_MED_SPEED adds +14, 16 in total.
MED_SPEED adds +10, 12 in total.
MED_HIGH_SPEED adds +6 ADCK, 8 in total.
HIGH_SPEED adds +4 ADCK, 6 in total.
HIGH_VERY_HIGH_SPEED adds +2 ADCK, 4 in total
VERY_HIGH_SPEED is the highest possible sampling speed (0 ADCK added, 2 in total).
*/
const enum ADC_settings::ADC_SAMPLING_SPEED samplingSpeeds[2] = {ADC_SAMPLING_SPEED::VERY_HIGH_SPEED, ADC_SAMPLING_SPEED::VERY_HIGH_SPEED};
/* For Teensy 4:
VERY_LOW_SPEED is guaranteed to be the lowest possible speed within specs (higher than 4 MHz).
LOW_SPEED is equal to VERY_LOW_SPEED
MED_SPEED is always >= ADC_LOW_SPEED and <= ADC_HIGH_SPEED.
HIGH_SPEED is guaranteed to be the highest possible speed within specs (lower or eq than 40 MHz).
VERY_HIGH_SPEED is equal to HIGH_SPEED
*/
const uint32_t interruptPin = 0;
volatile uint32_t triggerReset = true; // start true so initialize histogram & stats
uint32_t millisEarliestNextInterrupt = 0;
void interruptPressed() {
// wait before new interrupt (debounce)
uint32_t millisRead = millis();
if (millisRead <= millisEarliestNextInterrupt)
return;
millisEarliestNextInterrupt = millisRead + 200;
triggerReset = true;
}
void setup() {
pinMode(analogReadPin0, INPUT);
pinMode(analogReadPin1, INPUT);
pinMode(interruptPin, INPUT_PULLUP);
attachInterrupt(digitalPinToInterrupt(interruptPin), interruptPressed, FALLING);
Serial.begin(12000000);//115200);
adc->adc0->setAveraging(analogReadAveragingNum0); // set number of averages
adc->adc1->setAveraging(analogReadAveragingNum1); // set number of averages
adc->adc0->setResolution(analogReadBitDepth0); // set bits of resolution
adc->adc1->setResolution(analogReadBitDepth1); // set bits of resolution
adc->adc0->setConversionSpeed(conversionSpeeds[0]); // change the conversion speed
adc->adc1->setConversionSpeed(conversionSpeeds[1]); // change the conversion speed
adc->adc0->setSamplingSpeed(samplingSpeeds[0]); // change the sampling speed
adc->adc1->setSamplingSpeed(samplingSpeeds[1]); // change the sampling speed
adc->adc0->wait_for_cal(); // waits until calibration is finished and writes the corresponding registers
adc->adc1->wait_for_cal(); // waits until calibration is finished and writes the corresponding registers
}
volatile uint64_t measurementHistogram0[analogReadMax0];
volatile uint64_t measurementHistogram1[analogReadMax1];
uint64_t nMeasurements0;
uint64_t nMeasurements1;
uint32_t runNumber = 0;
uint32_t millisStartTimestamp;
volatile uint32_t nMeasurements0PerPrintFrame;
volatile uint32_t nMeasurements1PerPrintFrame;
void loop() {
if (triggerReset) {
triggerReset = false;
nMeasurements0 = 0;
nMeasurements1 = 0;
runNumber += 1;
// reset histogram arrays
for( uint32_t i = 0; i < analogReadMax0; i++ ) {
measurementHistogram0[i] = 0;
}
for( uint32_t i = 0; i < analogReadMax1; i++ ) {
measurementHistogram1[i] = 0;
}
millisStartTimestamp = millis();
}
nMeasurements0PerPrintFrame = 0;
nMeasurements1PerPrintFrame = 0;
adc->adc0->enableInterrupts(adc0_isr);
adc->adc1->enableInterrupts(adc1_isr);
uint32_t microsPrintFrameStartTime = micros();
adc->adc0->startContinuous(analogReadPin0);
adc->adc1->startContinuous(analogReadPin1);
delay (100); // take measurements for a while
adc->adc0->stopContinuous();
adc->adc1->stopContinuous();
uint32_t microsPrintFrameDuration = micros() - microsPrintFrameStartTime;
adc->adc0->disableInterrupts();
adc->adc1->disableInterrupts();
nMeasurements0 += (uint64_t) nMeasurements0PerPrintFrame;
nMeasurements1 += (uint64_t) nMeasurements1PerPrintFrame;
// end of taking measurements, now time to print summary statistics
Serial.print("run #");
Serial.print(runNumber);
Serial.print(" cumulative histogram after ");
Serial.print((float) millis() / 1000);
Serial.print(" seconds.");
Serial.println();
Serial.println();
// calculate stats
for( uint32_t adc_number = 0; adc_number < 2; adc_number++ ) {
volatile uint64_t *measurementHistogram = ( (adc_number == 0) ? measurementHistogram0 : measurementHistogram1);
uint64_t nMeasurementsPerPrintFrame = ( (adc_number == 0) ? nMeasurements0PerPrintFrame : nMeasurements1PerPrintFrame);
uint64_t nMeasurements = ( (adc_number == 0) ? nMeasurements0 : nMeasurements1);
uint32_t analogReadMax = ( (adc_number == 0) ? analogReadMax0 : analogReadMax1);
uint32_t analogReadBitDepth = ( (adc_number == 0) ? analogReadBitDepth0 : analogReadBitDepth1);
uint32_t analogReadAveragingNum = ( (adc_number == 0) ? analogReadAveragingNum0 : analogReadAveragingNum1);
Serial.print("ADC");
Serial.print(adc_number);
Serial.print(": ");
Serial.print("BitDepth=");
Serial.print(analogReadBitDepth);
Serial.print(", averaging=");
Serial.print(analogReadAveragingNum);
Serial.print(", nMeasurements=");
Serial.print(nMeasurements);
Serial.print(" @");
Serial.print((float) nMeasurementsPerPrintFrame * 1000.0f / microsPrintFrameDuration);
Serial.print("kHz (ADC_CONVERSION_SPEED=");
Serial.print((uint8_t) conversionSpeeds[adc_number]);
Serial.print(", ADC_SAMPLING_SPEED=");
Serial.print((uint8_t) samplingSpeeds[adc_number]);
Serial.println(").");
uint32_t minimum = (1 << analogReadBitDepth);
uint32_t maximum = 0;
uint64_t summation = 0;
for( uint32_t i = 0; i < analogReadMax; i++) {
if( measurementHistogram[i] > 0 ) {
summation += measurementHistogram[i] * i;
if( i < minimum )
minimum = i;
if( i > maximum )
maximum = i;
}
}
float mean = (float) summation / nMeasurements;
Serial.print("Measurement range of ");
Serial.print(maximum - minimum);
Serial.print(" from ");
Serial.print(minimum);
Serial.print(" to ");
Serial.print(maximum);
Serial.println('.');
Serial.println("[bin] count percent of total measurements");
float sumofsquares = 0;
for( uint32_t i=minimum; i<= maximum; i++) {
float differenceFromMean = (float) i - mean;
sumofsquares += (float) measurementHistogram[i] * (differenceFromMean * differenceFromMean);
Serial.print("[");
Serial.print(i);
Serial.print("]: ");
printRightJustifiedUnsignedInt(measurementHistogram[i]);
float percentOfTotal = (float) measurementHistogram[i] * 100.0f / nMeasurements;
Serial.print(' ');
for( int bars = (int64_t) measurementHistogram[i] * 100 / nMeasurements; bars >= 0; bars-- ) {
Serial.write('=');
}
Serial.print(' ');
Serial.print(percentOfTotal);
Serial.println('%');
}
Serial.println("normalized scale: 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%");
Serial.print("mean: ");
Serial.println(mean, 6);
float variance = sumofsquares / (float) nMeasurements;
Serial.print("var: ");
Serial.println(variance, 6);
float standardDeviation = sqrt(variance);
Serial.print("stdDev: ");
Serial.println(standardDeviation, 6);
Serial.println();
}
}
void adc0_isr(void) {
nMeasurements0PerPrintFrame++;
int measurement = adc->adc0->analogReadContinuous();
measurementHistogram0[measurement] += 1;
}
void adc1_isr(void) {
nMeasurements1PerPrintFrame++;
int measurement = adc->adc1->analogReadContinuous();
measurementHistogram1[measurement] += 1;
}
void printRightJustifiedUnsignedInt(uint32_t value) {
const int32_t maxDigits = 10;
uint32_t digits[maxDigits];
int32_t digitIndex = 0;
while( digitIndex < maxDigits ) {
digits[digitIndex] = value % 10;
value = value / 10;
if( value == 0 ) {
for( int32_t digitsLeft = digitIndex + 1; digitsLeft < maxDigits; digitsLeft++ ) {
Serial.write(' ');
}
break;
}
digitIndex++;
}
while (digitIndex >= 0) {
Serial.print(digits[digitIndex]);
digitIndex--;
}
}