[+] Firmware test

firmware/src/main.cpp

@@ -0,0 +1,70 @@
+#include <Arduino.h>
+#include <chrono>
+#include <cinttypes>
+
+#define u64 uint64_t
+#define timeMillis() std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::system_clock::now().time_since_epoch()).count()
+#define min(a, b) ((a) < (b) ? (a) : (b))
+
+u64 start_time = 0;
+
+const int NUM_SENSORS = 2;
+int pins[] = {34, 39};   // GPIO34
+int notes[] = {84, 86};  // C6, D6
+int lasts[NUM_SENSORS];  // variable to store the value coming from the sensor
+u64 last_hit_times[NUM_SENSORS];
+
+int max_sensor = 4096;
+int max_threshold = 700;
+int active_threshold = 400;  // Minimum value to be considered as a hit
+
+void setup()
+{
+    // Initialize pin and serial
+    for (int pin : pins) pinMode(pin, INPUT);
+    Serial.begin(9600);
+    Serial.printf("Initialized\r\n");
+
+    start_time = timeMillis();
+}
+
+/**
+ * Called when the sensor value changes
+ *
+ * @param id Sensor index
+ */
+void on_sensor_update(int id, u64 time, int last, int current)
+{
+    // If the last value is larger than the current value, check timeout
+    if (last > current && last > active_threshold) {
+        u64 elapsed = time - last_hit_times[id];
+        if (elapsed < 150) {
+            // If the last hit is too close, ignore this hit
+            return;
+        }
+
+        // The last value is a local maximum,
+        // and we read it as the hit strength of our note. Send midi command to the host.
+        // /hit <note> <velocity>
+        Serial.printf("/hit %d %d\r\n", notes[id], min((last - active_threshold) * 127 / (max_threshold - active_threshold), 127));
+
+        // Update last hit time
+        last_hit_times[id] = time;
+    }
+}
+
+void loop() {
+    u64 time = timeMillis();
+
+    // Read sensor value from each pin
+    for (int i = 0; i < NUM_SENSORS; i++) {
+        int v = analogRead(pins[i]);
+        if (v != lasts[i]) {
+            u64 elapsed = time - start_time;
+            Serial.printf("Sensor #%d - %" PRIu64 ": %d\r\n", i, elapsed, v);
+
+            on_sensor_update(i, time, lasts[i], v);
+        }
+        lasts[i] = v;
+    }
+}