\/*
\n Open\u2010Pond Ultrasonic Catfish Counter
\n ———————————–
\n Counts catfish echoes in a 1 m\u2013deep biofloc pond (~50 mL\/L solids) under
\n 10 L\/min aeration without using a flume. Implements:<\/p>\n
\u2022 Automatic baseline calibration (pond bottom distance)
\n \u2022 Burst of PING_COUNT pings \u2192 median\u2010filter gating
\n \u2022 Fish\/gas\u2010bubble separation via distance gating & median filter
\n \u2022 DROP_CM below bottom \u2192 fish event
\n \u2022 DEBOUNCE_MS to avoid double counts
\n \u2022 Periodic re\u2010baseline every RECALIBRATE_INTERVAL_S
\n \u2022 Logs \u201cFish #n @ t.s\u201d over Serial (swap-in SD\/MQTT easily)<\/p>\n
Hardware (HC-SR04):
\n TRIG \u2192 D7
\n ECHO \u2192 D6
\n VCC \u2192 5 V
\n GND \u2192 GND
\n*\/<\/p>\n
#include <Arduino.h><\/p>\n
\/\/ \u2500\u2500 USER CONFIG \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500
\n\/\/ pins
\nconst uint8_t PIN_TRIG = 7;
\nconst uint8_t PIN_ECHO = 6;<\/p>\n
\/\/ signal\u2010processing parameters
\nconst uint8_t MAX_BASELINE_SAMPLES = 30; \/\/ samples to calibrate bottom
\nconst uint8_t PING_COUNT = 7; \/\/ pings per detection burst
\nconst float DROP_CM = 8.0; \/\/ drop from bottom \u2192 fish
\nconst float MIN_DIST_CM = 20.0; \/\/ ignore echoes closer than this
\nconst float MAX_DIST_CM = 90.0; \/\/ ignore echoes deeper than this
\nconst uint16_t DEBOUNCE_MS = 300; \/\/ lockout after a detection
\nconst uint32_t RECALIBRATE_INTERVAL_S = 600; \/\/ re\u2010baseline every 10 min<\/p>\n
\/\/ runtime state
\nfloat bottomDist = 0.0; \/\/ calibrated pond\u2010bottom distance (cm)
\nfloat detectThresh = 0.0; \/\/ bottomDist – DROP_CM
\nuint32_t fishCount = 0; \/\/ total fish counted
\nuint32_t lastFishTS = 0; \/\/ timestamp of last detection
\nuint32_t lastRecalTS = 0; \/\/ timestamp of last re\u2010baseline<\/p>\n
void setup() {
\n Serial.begin(115200);
\n pinMode(PIN_TRIG, OUTPUT);
\n pinMode(PIN_ECHO, INPUT);<\/p>\n
Serial.println(F(“\\n\u27f3 Calibrating bottom baseline\u2026”));
\n bottomDist = calibrateBaseline();
\n detectThresh = bottomDist – DROP_CM;
\n lastRecalTS = millis();<\/p>\n
Serial.printf(“BottomDist=%.1f cm \u2192 fish if < %.1f cm\\n▶ Start counting\\n\\n”,
\n bottomDist, detectThresh);
\n}<\/p>\n
void loop() {
\n uint32_t now = millis();<\/p>\n
\/\/ 1) Periodic re\u2010baseline
\n if (now – lastRecalTS >= RECALIBRATE_INTERVAL_S * 1000UL) {
\n Serial.println(F(“\u27f3 Recalibrating baseline\u2026”));
\n bottomDist = calibrateBaseline();
\n detectThresh = bottomDist – DROP_CM;
\n lastRecalTS = now;
\n Serial.printf(“New BottomDist=%.1f cm thresh<%.1f cm\\n\\n”,
\n bottomDist, detectThresh);
\n }<\/p>\n
\/\/ 2) Burst of ultrasonic pings
\n float readings[PING_COUNT];
\n for (uint8_t i = 0; i < PING_COUNT; i++) {
\n readings[i] = measureDistance();
\n delay(20); \/\/ ~50 Hz burst to outrun bubble motion
\n }<\/p>\n
\/\/ 3) Median\u2010filter to reject transient bubble\/floc echoes
\n float med = medianFilter(readings, PING_COUNT);<\/p>\n
\/\/ 4) Distance gating + fish detection + debounce
\n if (med > MIN_DIST_CM && med < detectThresh
\n && (now – lastFishTS > DEBOUNCE_MS)) {
\n fishCount++;
\n lastFishTS = now;
\n Serial.printf(“🐟 Fish #%lu @ %.2f s\\n”,
\n fishCount, now \/ 1000.0f);
\n }<\/p>\n
delay(100);
\n}<\/p>\n
\/\/ \u2500\u2500 UTILITIES \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500<\/p>\n
\/\/ send one HC-SR04 ping; return cm or -1 on timeout
\nfloat measureDistance() {
\n digitalWrite(PIN_TRIG, LOW);
\n delayMicroseconds(2);
\n digitalWrite(PIN_TRIG, HIGH);
\n delayMicroseconds(10);
\n digitalWrite(PIN_TRIG, LOW);<\/p>\n
long us = pulseIn(PIN_ECHO, HIGH, 30000); \/\/ 30 ms timeout
\n if (us == 0) return -1.0;
\n return (us \/ 2.0) \/ 29.1; \/\/ \u00b5s\u2192cm
\n}<\/p>\n
\/\/ average MAX_BASELINE_SAMPLES valid pings for bottomDist
\nfloat calibrateBaseline() {
\n float sum = 0;
\n uint8_t cnt = 0;
\n while (cnt < MAX_BASELINE_SAMPLES) {
\n float d = measureDistance();
\n if (d > 0) {
\n sum += d;
\n cnt++;
\n }
\n delay(100);
\n }
\n return sum \/ cnt;
\n}<\/p>\n
\/\/ simple insertion sort \u2192 return median element
\nfloat medianFilter(float *arr, uint8_t n) {
\n for (uint8_t i = 1; i < n; i++) {
\n float key = arr[i];
\n int8_t j = i – 1;
\n while (j >= 0 && arr[j] > key) {
\n arr[j + 1] = arr[j];
\n j–;
\n }
\n arr[j + 1] = key;
\n }
\n return arr[n \/ 2];
\n}<\/p>\n\n\n\n
Signal-Processing Tip<\/p>\n\n\n\n
\/*
\n\u00a0 Open-Pond Ultrasonic Catfish Counter
\n\u00a0 ———————————–
\n\u00a0 Counts catfish echoes in a 1 m-deep biofloc pond (~50 mL\/L solids)
\n\u00a0 under 10 L\/min aeration\u2014no flume required.<\/p>\n
\u00a0 \u2022 Auto-calibrates bottom distance (MAX_BASELINE_SAMPLES)
\n\u00a0 \u2022 Fires a burst of PING_COUNT pings \u2192 median-filter gating
\n\u00a0 \u2022 Only counts echoes between MIN_DIST_CM and (bottomDist-DROP_CM)
\n\u00a0 \u2022 DEBOUNCE_MS locks out after each detection
\n\u00a0 \u2022 Periodic re-baseline every RECALIBRATE_INTERVAL_S
\n\u00a0 \u2022 Logs \u201cFish #n @ t.s\u201d on Serial (swap for SD\/MQTT as needed)<\/p>\n
\u00a0 HC-SR04 wiring:
\n\u00a0\u00a0\u00a0 TRIG \u2192 D7
\n\u00a0\u00a0\u00a0 ECHO \u2192 D6
\n\u00a0\u00a0\u00a0 VCC\u00a0 \u2192 5 V
\n\u00a0\u00a0\u00a0 GND\u00a0 \u2192 GND
\n*\/<\/p>\n
#include <Arduino.h><\/p>\n
\/\/ \u2500\u2500 USER CONFIG \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500
\nconst uint8_t\u00a0 PIN_TRIG\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 = 7;\u00a0\u00a0\u00a0\u00a0\u00a0 \/\/ HC-SR04 TRIG pin
\nconst uint8_t\u00a0 PIN_ECHO\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 = 6;\u00a0\u00a0\u00a0\u00a0\u00a0 \/\/ HC-SR04 ECHO pin<\/p>\n
const uint8_t\u00a0 MAX_BASELINE_SAMPLES\u00a0\u00a0 = 30;\u00a0\u00a0\u00a0\u00a0 \/\/ samples for bottom calibration
\nconst uint8_t\u00a0 PING_COUNT\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 = 7;\u00a0\u00a0\u00a0\u00a0\u00a0 \/\/ pings per detection burst
\nconst float\u00a0\u00a0\u00a0 DROP_CM\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 = 8.0;\u00a0\u00a0\u00a0 \/\/ drop below bottom \u2192 fish event
\nconst float\u00a0\u00a0\u00a0 MIN_DIST_CM\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 = 20.0;\u00a0\u00a0 \/\/ ignore echoes closer than this (cm)
\nconst float\u00a0\u00a0\u00a0 MAX_DIST_CM\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 = 95.0;\u00a0\u00a0 \/\/ ignore echoes deeper than this (cm)
\nconst uint16_t DEBOUNCE_MS\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 = 300;\u00a0\u00a0\u00a0 \/\/ ms lockout per fish
\nconst uint32_t RECALIBRATE_INTERVAL_S = 600;\u00a0\u00a0\u00a0 \/\/ seconds between re\u2010baselines<\/p>\n
\/\/ \u2500\u2500 RUNTIME STATE \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500
\nfloat\u00a0\u00a0\u00a0 bottomDist\u00a0\u00a0 = 0.0;\u00a0\u00a0 \/\/ calibrated pond bottom distance (cm)
\nfloat\u00a0\u00a0\u00a0 detectThresh = 0.0;\u00a0\u00a0 \/\/ bottomDist \u2212 DROP_CM
\nuint32_t fishCount\u00a0\u00a0\u00a0 = 0;\u00a0\u00a0\u00a0\u00a0 \/\/ total fish counted
\nuint32_t lastFishTS\u00a0\u00a0 = 0;\u00a0\u00a0\u00a0\u00a0 \/\/ millis() of last count
\nuint32_t lastRecalTS\u00a0 = 0;\u00a0\u00a0\u00a0\u00a0 \/\/ millis() of last baseline<\/p>\n
\/\/ \u2500\u2500 SETUP \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500
\nvoid setup() {
\n\u00a0 Serial.begin(115200);
\n\u00a0 pinMode(PIN_TRIG, OUTPUT);
\n\u00a0 pinMode(PIN_ECHO, INPUT);<\/p>\n
\u00a0 Serial.println(F(“\\n\u27f3 Calibrating bottom baseline\u2026”));
\n\u00a0 bottomDist\u00a0\u00a0 = calibrateBaseline();
\n\u00a0 detectThresh = bottomDist – DROP_CM;
\n\u00a0 lastRecalTS\u00a0 = millis();<\/p>\n
\u00a0 Serial.printf(“BottomDist=%.1f cm \u2192 count if < %.1f cm\\n▶ Counting started\\n\\n”,
\n\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 bottomDist, detectThresh);
\n}<\/p>\n
\/\/ \u2500\u2500 MAIN LOOP \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500
\nvoid loop() {
\n\u00a0 uint32_t now = millis();<\/p>\n
\u00a0 \/\/ 1) Periodic bottom re-calibration
\n\u00a0 if (now – lastRecalTS >= RECALIBRATE_INTERVAL_S * 1000UL) {
\n\u00a0\u00a0\u00a0 Serial.println(F(“\u27f3 Re-calibrating bottom baseline\u2026”));
\n\u00a0\u00a0\u00a0 bottomDist\u00a0\u00a0 = calibrateBaseline();
\n\u00a0\u00a0\u00a0 detectThresh = bottomDist – DROP_CM;
\n\u00a0\u00a0\u00a0 lastRecalTS\u00a0 = now;
\n\u00a0\u00a0\u00a0 Serial.printf(“New BottomDist=%.1f cm \u2192 thresh<%.1f cm\\n\\n”,
\n\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 bottomDist, detectThresh);
\n\u00a0 }<\/p>\n
\u00a0 \/\/ 2) Burst of ultrasonic pings
\n\u00a0 float readings[PING_COUNT];
\n\u00a0 for (uint8_t i = 0; i < PING_COUNT; i++) {
\n\u00a0\u00a0\u00a0 readings[i] = measureDistance();
\n\u00a0\u00a0\u00a0 delay(20);\u00a0 \/\/ \u224850 Hz to outrun bubble motion
\n\u00a0 }<\/p>\n
\u00a0 \/\/ 3) Median-filter gating
\n\u00a0 float med = medianFilter(readings, PING_COUNT);<\/p>\n
\u00a0 \/\/ 4) Fish detection + debounce + distance gating
\n\u00a0 if (med > MIN_DIST_CM && med < detectThresh &&
\n\u00a0\u00a0\u00a0\u00a0\u00a0 (now – lastFishTS > DEBOUNCE_MS)) {
\n\u00a0\u00a0\u00a0 fishCount++;
\n\u00a0\u00a0\u00a0 lastFishTS = now;
\n\u00a0\u00a0\u00a0 Serial.printf(“\uf41f Fish #%lu @ %.2f s\\n”,
\n\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 fishCount, now \/ 1000.0f);
\n\u00a0 }<\/p>\n
\u00a0 delay(100);
\n}<\/p>\n
\/\/ \u2500\u2500 UTILITY FUNCTIONS \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500<\/p>\n
\/\/ Send one HC-SR04 ping \u2192 return cm or \u20131 on timeout
\nfloat measureDistance() {
\n\u00a0 digitalWrite(PIN_TRIG, LOW);
\n\u00a0 delayMicroseconds(2);
\n\u00a0 digitalWrite(PIN_TRIG, HIGH);
\n\u00a0 delayMicroseconds(10);
\n\u00a0 digitalWrite(PIN_TRIG, LOW);<\/p>\n
\u00a0 long duration = pulseIn(PIN_ECHO, HIGH, 30000);\u00a0 \/\/ 30 ms timeout
\n\u00a0 if (duration == 0) return -1.0;
\n\u00a0 return (duration \/ 2.0) \/ 29.1;\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \/\/ \u00b5s \u2192 cm
\n}<\/p>\n
\/\/ Calibrate bottom distance: average MAX_BASELINE_SAMPLES valid readings
\nfloat calibrateBaseline() {
\n\u00a0 float sum = 0;
\n\u00a0 uint8_t cnt = 0;
\n\u00a0 while (cnt < MAX_BASELINE_SAMPLES) {
\n\u00a0\u00a0\u00a0 float d = measureDistance();
\n\u00a0\u00a0\u00a0 if (d > 0 && d < MAX_DIST_CM) {
\n\u00a0\u00a0\u00a0\u00a0\u00a0 sum += d;
\n\u00a0\u00a0\u00a0\u00a0\u00a0 cnt++;
\n\u00a0\u00a0\u00a0 }
\n\u00a0\u00a0\u00a0 delay(100);
\n\u00a0 }
\n\u00a0 return sum \/ cnt;
\n}<\/p>\n
\/\/ Simple insertion sort + return middle element as median
\nfloat medianFilter(float *arr, uint8_t n) {
\n\u00a0 for (uint8_t i = 1; i < n; i++) {
\n\u00a0\u00a0\u00a0 float key = arr[i];
\n\u00a0\u00a0\u00a0 int8_t j = i – 1;
\n\u00a0\u00a0\u00a0 while (j >= 0 && arr[j] > key) {
\n\u00a0\u00a0\u00a0\u00a0\u00a0 arr[j + 1] = arr[j];
\n\u00a0\u00a0\u00a0\u00a0\u00a0 j–;
\n\u00a0\u00a0\u00a0 }
\n\u00a0\u00a0\u00a0 arr[j + 1] = key;
\n\u00a0 }
\n\u00a0 return arr[n \/ 2];
\n}<\/p>\n\n\n\n
Signal-Processing Tip<\/p>\n\n\n\n
Here\u2019s a turnkey Arduino sketch for counting catfish passing single-file through a 6\u20138 cm flume, optimized for a 1 m-deep biofloc pond (\u224850 mL\/L solids) with 10 L\/min aeration. It:<\/strong><\/p>\n\n\n\n \/* Hardware: Features: #include <Arduino.h><\/p>\n \/\/ USER CONFIGURATION const uint8_t MAX_READS = 30; \/\/ samples for baseline \/\/ RUNTIME STATE void setup() { Serial.println(F(“\\n\u27f3 Calibrating baseline\u2026”)); Serial.printf(“Baseline = %.1f cm \u2192 detect if < %.1f cm\\n”, void loop() { \/\/ Auto-recalibrate baseline periodically \/\/ 1) Burst-ping and store readings \/\/ 2) Median filter to reject transient bubble\/floc spikes \/\/ 3) Fish detection & debounce delay(100); \/\/ SENDS ONE PING, RETURNS cm OR \u20131 ON TIMEOUT long us = pulseIn(PIN_ECHO, HIGH, 30000); \/\/ 30 ms timeout \/\/ AVERAGES MAX_READS VALID PINGS FOR BASELINE \/\/ SIMPLE INSERTION SORT \u2192 RETURN MIDDLE ELEMENT \/* \u2013 HC-SR04 mounted across a 6\u20138 cm PVC flume Features: #include <Arduino.h><\/p>\n \/\/ USER SETTINGS \/\/ STATE void setup() { Serial.println(“\\n\u27f3 Calibrating baseline\u2026”); Serial.printf(“Baseline=%.1f cm \u2192 thresh<%.1f cm\\n▶ Starting counts\\n\\n”, void loop() { \/\/ periodic baseline recalibration \/\/ 1) burst-ping \/\/ 2) median filter \/\/ 3) detect + debounce delay(100); \/\/ \u2014 measureDist() \u2014 one HC-SR04 ping \u2192 cm or \u20131 \/\/ \u2014 calibrateBaseline() \u2014 avg of MAX_READS valid pings \/\/ \u2014 median() \u2014 insertion-sort & return arr[n\/2] \/* #include <Arduino.h><\/p>\n \/\/ \u2500\u2500 USER CONFIG \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 const uint8_t MAX_READS = 30; \/\/ calibration pings count \/\/ \u2500\u2500 RUNTIME STATE \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 \/\/ \u2500\u2500 SETUP \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 Serial.println(F(“\\n\u27f3 Calibrating baseline distance\u2026”)); Serial.printf(“Baseline = %.1f cm \u2192 detect if < %.1f cm\\n”, \/\/ \u2500\u2500 MAIN LOOP \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 \/\/ 1) Periodic re-calibration \/\/ 2) Burst of ultrasonic pings \/\/ 3) Median filter to reject transient echoes \/\/ 4) Fish detection + debounce delay(100); \/\/ \u2500\u2500 FUNCTIONS \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500<\/p>\n \/\/ measureDistance(): sends an HC-SR04 ping, returns cm or \u20131 on timeout long duration = pulseIn(PIN_ECHO, HIGH, 30000); \/\/ 30 ms timeout \/\/ calibrateBaseline(): averages MAX_READS valid readings for baseline \/\/ medianFilter(): simple insertion sort \u2192 returns middle element Signal-Processing Tip \/* Hardware: Features: #include <Arduino.h><\/p>\n \/\/\u2500\u2500 USER CONFIG \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 const uint8_t MAX_READS = 30; \/\/ baseline samples \/\/\u2500\u2500 RUNTIME STATE \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 \/\/\u2500\u2500 SETUP \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 Serial.println(F(“\\n\u2014 Calibrating baseline distance \u2014”)); Serial.printf(“Baseline: %.1f cm \u2794 Threshold: < %.1f cm\\n”, \/\/\u2500\u2500 LOOP \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 \/\/ Periodic baseline re-calibration \/\/ 1) Burst pings \u2192 store readings \/\/ 2) Median filter to reject bubbles\/floc \/\/ 3) Fish detection + debounce delay(100); \/\/\u2500\u2500 MEASURE DISTANCE \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 long us = pulseIn(PIN_ECHO, HIGH, 30000); \/\/ 30 ms timeout \/\/\u2500\u2500 BASELINE CALIBRATION \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 \/\/\u2500\u2500 MEDIAN FILTER \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 It: Signal-Processing Tip Signal-Processing Tip Here\u2019s a turnkey Arduino sketch for counting catfish passing single-file through a 6\u20138 cm flume, optimized for a 1 m-deep biofloc pond (\u224850 mL\/L solids) with…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[],"class_list":["post-344","post","type-post","status-publish","format-standard","hentry","category-bioflok"],"_links":{"self":[{"href":"https:\/\/www.eatmaja.co.id\/eka\/wp-json\/wp\/v2\/posts\/344","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.eatmaja.co.id\/eka\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.eatmaja.co.id\/eka\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.eatmaja.co.id\/eka\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.eatmaja.co.id\/eka\/wp-json\/wp\/v2\/comments?post=344"}],"version-history":[{"count":0,"href":"https:\/\/www.eatmaja.co.id\/eka\/wp-json\/wp\/v2\/posts\/344\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.eatmaja.co.id\/eka\/wp-json\/wp\/v2\/media?parent=344"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.eatmaja.co.id\/eka\/wp-json\/wp\/v2\/categories?post=344"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.eatmaja.co.id\/eka\/wp-json\/wp\/v2\/tags?post=344"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}\n
\n Biofloc Ultrasonic Catfish Counter
\n Pond depth: 1 m | Biofloc: ~50 mL\/L | Aeration: 10 L\/min<\/p>\n
\n \u2022 HC-SR04 ultrasonic sensor (2\u2013400 cm range)
\n \u2022 Mounted across a 6\u20138 cm PVC\/acrylic flume
\n \u2022 TRIG \u2192 D7, ECHO \u2192 D6, VCC \u2192 5 V, GND \u2192 GND
\n \u2022 (Optional bubble-skirt 3D-printed around transducer)<\/p>\n
\n \u2022 Auto baseline calibration (MAX_READS samples)
\n \u2022 Burst of PINGS readings \u2192 median filter for bubble\/floc rejection
\n \u2022 DROP_CM below baseline \u2192 fish event
\n \u2022 DEBOUNCE_MS to avoid double-counts
\n \u2022 Re-calibrate baseline every RECALIBRATE_S seconds
\n*\/<\/p>\n
\nconst uint8_t PIN_TRIG = 7;
\nconst uint8_t PIN_ECHO = 6;<\/p>\n
\nconst uint8_t PINGS = 7; \/\/ pings per detection burst
\nconst float DROP_CM = 6.0; \/\/ cm drop = fish event
\nconst uint16_t DEBOUNCE_MS = 250; \/\/ ms ignore window
\nconst uint32_t RECALIBRATE_S = 600; \/\/ seconds between auto-recalibrations<\/p>\n
\nfloat baselineDist = 0.0;
\nfloat detectThresh = 0.0;
\nuint32_t fishCount = 0;
\nuint32_t lastFishTS = 0;
\nuint32_t lastRecalTS = 0;<\/p>\n
\n Serial.begin(115200);
\n pinMode(PIN_TRIG, OUTPUT);
\n pinMode(PIN_ECHO, INPUT);<\/p>\n
\n baselineDist = calibrateBaseline();
\n detectThresh = baselineDist – DROP_CM;
\n lastRecalTS = millis();<\/p>\n
\n baselineDist, detectThresh);
\n Serial.println(F(“▶ Start counting\\n”));
\n}<\/p>\n
\n uint32_t now = millis();<\/p>\n
\n if (now – lastRecalTS >= RECALIBRATE_S * 1000UL) {
\n Serial.println(F(“\u27f3 Re-calibrating baseline\u2026”));
\n baselineDist = calibrateBaseline();
\n detectThresh = baselineDist – DROP_CM;
\n lastRecalTS = now;
\n Serial.printf(“New baseline = %.1f cm Thresh = < %.1f cm\\n\\n”,
\n baselineDist, detectThresh);
\n }<\/p>\n
\n float buf[PINGS];
\n for (uint8_t i = 0; i < PINGS; i++) {
\n buf[i] = measureDist();
\n delay(20); \/\/ ~50 Hz burst to outrun bubble motion
\n }<\/p>\n
\n float med = median(buf, PINGS);<\/p>\n
\n if (med > 0 && med < detectThresh
\n && (now – lastFishTS > DEBOUNCE_MS)) {
\n fishCount++;
\n lastFishTS = now;
\n Serial.printf(“Fish #%lu @ %.2f s\\n”,
\n fishCount, now \/ 1000.0f);
\n }<\/p>\n
\n}<\/p>\n
\nfloat measureDist() {
\n digitalWrite(PIN_TRIG, LOW);
\n delayMicroseconds(2);
\n digitalWrite(PIN_TRIG, HIGH);
\n delayMicroseconds(10);
\n digitalWrite(PIN_TRIG, LOW);<\/p>\n
\n if (us == 0) return -1.0;
\n return (us \/ 2.0) \/ 29.1; \/\/ \u00b5s\u2192cm
\n}<\/p>\n
\nfloat calibrateBaseline() {
\n float sum = 0;
\n uint8_t cnt = 0;
\n while (cnt < MAX_READS) {
\n float d = measureDist();
\n if (d > 0) {
\n sum += d;
\n cnt++;
\n }
\n delay(100);
\n }
\n return sum \/ cnt;
\n}<\/p>\n
\nfloat median(float *arr, uint8_t n) {
\n for (uint8_t i = 1; i < n; i++) {
\n float key = arr[i];
\n int8_t j = i – 1;
\n while (j >= 0 && arr[j] > key) {
\n arr[j+1] = arr[j];
\n j–;
\n }
\n arr[j+1] = key;
\n }
\n return arr[n\/2];
\n}<\/p>\n\n\n
\n Biofloc Ultrasonic Catfish Counter
\n Pond depth: 1 m | Aeration: 10 L\/min | Floc: ~50 mL\/L<\/p>\n
\n \u2013 TRIG\u2192D7, ECHO\u2192D6, VCC\u21925 V, GND\u2192GND
\n \u2013 Optional bubble-skirt around transducer<\/p>\n
\n 1. Auto baseline (MAX_READS)
\n 2. Burst of PINGS \u2192 median filter
\n 3. DROP_CM below baseline \u2192 fish event
\n 4. DEBOUNCE_MS per-fish
\n 5. Re-baseline every RECALIBRATE_S seconds
\n*\/<\/p>\n
\nconst uint8_t PIN_TRIG = 7;
\nconst uint8_t PIN_ECHO = 6;
\nconst uint8_t MAX_READS = 30; \/\/ baseline samples
\nconst uint8_t PINGS = 7; \/\/ pings per burst
\nconst float DROP_CM = 6.0; \/\/ cm drop = fish event
\nconst uint16_t DEBOUNCE_MS = 250; \/\/ ms ignore window
\nconst uint32_t RECALIB_S = 600; \/\/ baseline recal every 10 min<\/p>\n
\nfloat baselineDist = 0, detectThresh = 0;
\nuint32_t fishCount = 0, lastFishTS = 0, lastRecalTS = 0;<\/p>\n
\n Serial.begin(115200);
\n pinMode(PIN_TRIG, OUTPUT);
\n pinMode(PIN_ECHO, INPUT);<\/p>\n
\n baselineDist = calibrateBaseline();
\n detectThresh = baselineDist – DROP_CM;
\n lastRecalTS = millis();<\/p>\n
\n baselineDist, detectThresh);
\n}<\/p>\n
\n uint32_t now = millis();<\/p>\n
\n if (now – lastRecalTS >= RECALIB_S*1000UL) {
\n Serial.println(“\u27f3 Re-calibrating baseline\u2026”);
\n baselineDist = calibrateBaseline();
\n detectThresh = baselineDist – DROP_CM;
\n lastRecalTS = now;
\n Serial.printf(“New baseline=%.1f cm thresh<%.1f cm\\n\\n”,
\n baselineDist, detectThresh);
\n }<\/p>\n
\n float buf[PINGS];
\n for (uint8_t i = 0; i < PINGS; i++) {
\n buf[i] = measureDist();
\n delay(20); \/\/ 50 Hz
\n }<\/p>\n
\n float m = median(buf, PINGS);<\/p>\n
\n if (m > 0 && m < detectThresh && now – lastFishTS > DEBOUNCE_MS) {
\n fishCount++;
\n lastFishTS = now;
\n Serial.printf(“🐟 #%lu @ %.2f s\\n”, fishCount, now\/1000.0f);
\n }<\/p>\n
\n}<\/p>\n
\nfloat measureDist() {
\n digitalWrite(PIN_TRIG, LOW); delayMicroseconds(2);
\n digitalWrite(PIN_TRIG, HIGH); delayMicroseconds(10);
\n digitalWrite(PIN_TRIG, LOW);
\n long us = pulseIn(PIN_ECHO, HIGH, 30000);
\n if (!us) return -1;
\n return (us\/2.0) \/ 29.1;
\n}<\/p>\n
\nfloat calibrateBaseline() {
\n float sum = 0; uint8_t cnt = 0;
\n while (cnt < MAX_READS) {
\n float d = measureDist();
\n if (d > 0) { sum += d; cnt++; }
\n delay(100);
\n }
\n return sum \/ cnt;
\n}<\/p>\n
\nfloat median(float *arr, uint8_t n) {
\n for (uint8_t i = 1; i < n; i++) {
\n float k = arr[i]; int8_t j = i-1;
\n while (j>=0 && arr[j] > k) { arr[j+1] = arr[j]; j–; }
\n arr[j+1] = k;
\n }
\n return arr[n\/2];
\n}<\/p>\n\n\n
\n Biofloc Ultrasonic Catfish Counter
\n ———————————-
\n Counts catfish passing single\u2010file through a 6\u20138cm flume in a 1m-deep biofloc pond
\n (\u224850 mL\/L solids) with 10 L\/min aeration.
\n Implements:
\n \u2022 Auto baseline calibration (MAX_READS samples)
\n \u2022 Burst of PINGS ultrasonic pings \u2192 median filter for bubble\/floc rejection
\n \u2022 DROP_CM below baseline \u2192 fish event
\n \u2022 DEBOUNCE_MS to avoid double-counts
\n \u2022 Periodic baseline re-calibration every RECALIBRATE_S seconds
\n \u2022 Serial log: \u201cFish #n @ t.s\u201d (swap for SD or MQTT as needed)
\n*\/<\/p>\n
\nconst uint8_t PIN_TRIG = 7; \/\/ HC-SR04 TRIG pin
\nconst uint8_t PIN_ECHO = 6; \/\/ HC-SR04 ECHO pin<\/p>\n
\nconst uint8_t PINGS = 7; \/\/ pings per detection burst
\nconst float DROP_CM = 6.0; \/\/ cm drop from baseline \u2192 fish
\nconst uint16_t DEBOUNCE_MS = 250; \/\/ ms ignore after a count
\nconst uint32_t RECALIBRATE_S = 600; \/\/ seconds between auto-recalibrations<\/p>\n
\nfloat baselineDist = 0.0; \/\/ calibrated avg distance (cm)
\nfloat detectThresh = 0.0; \/\/ baselineDist \u2013 DROP_CM
\nuint32_t fishCount = 0; \/\/ total fish counted
\nuint32_t lastFishTS = 0; \/\/ timestamp of last count
\nuint32_t lastRecalTS = 0; \/\/ timestamp of last recalibration<\/p>\n
\nvoid setup() {
\n Serial.begin(115200);
\n pinMode(PIN_TRIG, OUTPUT);
\n pinMode(PIN_ECHO, INPUT);<\/p>\n
\n baselineDist = calibrateBaseline();
\n detectThresh = baselineDist – DROP_CM;
\n lastRecalTS = millis();<\/p>\n
\n baselineDist, detectThresh);
\n Serial.println(F(“▶ Starting fish counting\u2026\\n”));
\n}<\/p>\n
\nvoid loop() {
\n uint32_t now = millis();<\/p>\n
\n if (now – lastRecalTS >= RECALIBRATE_S * 1000UL) {
\n Serial.println(F(“\\n\u27f3 Re-calibrating baseline\u2026”));
\n baselineDist = calibrateBaseline();
\n detectThresh = baselineDist – DROP_CM;
\n lastRecalTS = now;
\n Serial.printf(“New baseline = %.1f cm Thresh = < %.1f cm\\n\\n”,
\n baselineDist, detectThresh);
\n }<\/p>\n
\n float readings[PINGS];
\n for (uint8_t i = 0; i < PINGS; i++) {
\n readings[i] = measureDistance();
\n delay(20); \/\/ 50 Hz burst to outrun bubble movement
\n }<\/p>\n
\n float med = medianFilter(readings, PINGS);<\/p>\n
\n if (med > 0 && med < detectThresh &&
\n (now – lastFishTS > DEBOUNCE_MS)) {
\n fishCount++;
\n lastFishTS = now;
\n Serial.printf(“🐟 Fish #%lu @ %.2f s\\n”,
\n fishCount, now \/ 1000.0f);
\n }<\/p>\n
\n}<\/p>\n
\nfloat measureDistance() {
\n digitalWrite(PIN_TRIG, LOW);
\n delayMicroseconds(2);
\n digitalWrite(PIN_TRIG, HIGH);
\n delayMicroseconds(10);
\n digitalWrite(PIN_TRIG, LOW);<\/p>\n
\n if (duration == 0) return -1.0;
\n return (duration \/ 2.0) \/ 29.1; \/\/ \u00b5s\u2192cm
\n}<\/p>\n
\nfloat calibrateBaseline() {
\n float sum = 0;
\n uint8_t count = 0;
\n while (count < MAX_READS) {
\n float d = measureDistance();
\n if (d > 0) {
\n sum += d;
\n count++;
\n }
\n delay(100);
\n }
\n return sum \/ count;
\n}<\/p>\n
\nfloat medianFilter(float *arr, uint8_t n) {
\n for (uint8_t i = 1; i < n; i++) {
\n float key = arr[i];
\n int8_t j = i – 1;
\n while (j >= 0 && arr[j] > key) {
\n arr[j + 1] = arr[j];
\n j–;
\n }
\n arr[j + 1] = key;
\n }
\n return arr[n \/ 2];
\n}<\/p>\n\n\n\n
By firing 7 quick pings at ~50 Hz and taking the median distance, you suppress one-off echoes from fast-rising bubbles or dense floc clumps. Meanwhile, periodic re-baseline calibration tracks slow drifts (temperature, floc buildup) so your DROP_CM threshold stays tuned over long runs under 10 L\/min aeration.<\/p>\n\n\n
\n Biofloc Ultrasonic Catfish Counter
\n Pond depth: 1 m, biofloc ~50 mL\/L, heavy aeration<\/p>\n
\n \u2022 HC-SR04 or equivalent narrow-beam ultrasonic module
\n \u2022 Mounted across a 6\u20138 cm flume channel (PVC\/acrylic)
\n \u2022 TRIG \u2192 D7, ECHO \u2192 D6, VCC \u2192 5 V, GND \u2192 GND<\/p>\n
\n 1) Automatic baseline calibration (MAX_READS samples)
\n 2) Detection bursts of PINGS readings \u2192 median filtering
\n 3) Dynamic threshold: DROP_CM below baseline
\n 4) DEBOUNCE_MS to avoid double-counts
\n 5) Runtime re-calibration every RECALIBRATE_S seconds
\n*\/<\/p>\n
\nconst uint8_t PIN_TRIG = 7;
\nconst uint8_t PIN_ECHO = 6;<\/p>\n
\nconst uint8_t PINGS = 7; \/\/ pings per detection burst
\nconst float DROP_CM = 6.0; \/\/ cm drop = fish event
\nconst uint16_t DEBOUNCE_MS = 250; \/\/ ms ignore window
\nconst uint32_t RECALIBRATE_S = 600; \/\/ re-calibrate baseline every 10 min<\/p>\n
\nfloat baselineDist = 0.0;
\nfloat detectThresh = 0.0;
\nuint32_t fishCount = 0;
\nuint32_t lastFishTS = 0;
\nuint32_t lastRecalTS = 0;<\/p>\n
\nvoid setup() {
\n Serial.begin(115200);
\n pinMode(PIN_TRIG, OUTPUT);
\n pinMode(PIN_ECHO, INPUT);<\/p>\n
\n baselineDist = calibrateBaseline();
\n detectThresh = baselineDist – DROP_CM;
\n lastRecalTS = millis();<\/p>\n
\n baselineDist, detectThresh);
\n Serial.println(F(“\u2014 START COUNTING \u2014\\n”));
\n}<\/p>\n
\nvoid loop() {
\n uint32_t now = millis();<\/p>\n
\n if (now – lastRecalTS >= RECALIBRATE_S * 1000UL) {
\n baselineDist = calibrateBaseline();
\n detectThresh = baselineDist – DROP_CM;
\n lastRecalTS = now;
\n Serial.printf(“Re-calibrated baseline: %.1f cm Thresh: < %.1f cm\\n”,
\n baselineDist, detectThresh);
\n }<\/p>\n
\n float buf[PINGS];
\n for (uint8_t i = 0; i < PINGS; i++) {
\n buf[i] = measureDist();
\n delay(20); \/\/ 50 Hz ping burst
\n }<\/p>\n
\n float med = median(buf, PINGS);<\/p>\n
\n if (med > 0 && med < detectThresh && (now – lastFishTS > DEBOUNCE_MS)) {
\n fishCount++;
\n lastFishTS = now;
\n Serial.printf(“Fish #%lu @ %.2f s\\n”,
\n fishCount, now \/ 1000.0f);
\n }<\/p>\n
\n}<\/p>\n
\n\/\/ Sends one HC-SR04 ping, returns distance in cm or -1 on timeout
\nfloat measureDist() {
\n digitalWrite(PIN_TRIG, LOW);
\n delayMicroseconds(2);
\n digitalWrite(PIN_TRIG, HIGH);
\n delayMicroseconds(10);
\n digitalWrite(PIN_TRIG, LOW);<\/p>\n
\n if (us == 0) return -1.0;
\n return (us \/ 2.0) \/ 29.1;
\n}<\/p>\n
\n\/\/ Averages MAX_READS valid pings for a stable baseline
\nfloat calibrateBaseline() {
\n float sum = 0;
\n uint8_t cnt = 0;
\n while (cnt < MAX_READS) {
\n float d = measureDist();
\n if (d > 0) {
\n sum += d;
\n cnt++;
\n }
\n delay(100);
\n }
\n return sum \/ cnt;
\n}<\/p>\n
\n\/\/ Simple insertion sort + return middle value
\nfloat median(float *arr, uint8_t n) {
\n for (uint8_t i = 1; i < n; i++) {
\n float key = arr[i];
\n int8_t j = i – 1;
\n while (j >= 0 && arr[j] > key) {
\n arr[j+1] = arr[j];
\n j–;
\n }
\n arr[j+1] = key;
\n }
\n return arr[n\/2];
\n}<\/p>\n\n\n\n
\u2022 Calibrates a dynamic baseline to the back-wall reflector
\u2022 Fires bursts of PINGS ultrasonic readings, applies a median filter to reject bubble\/floc spikes
\u2022 Flags a \u201cfish event\u201d when the median drops by DROP_CM
\u2022 Debounces so you get exactly one count per crossing
\u2022 Logs \u201cFish #n @ t s\u201d to Serial (swap for SD\/MQTT as needed) <\/p>\n","protected":false},"excerpt":{"rendered":"