Implement sync (e.g. after reset)

microcontroller/ctrl.py

@@ -1,5 +1,6 @@
 import serial
 import time
+import colorsys
 
 channels = [
     192,  # pan
@@ -18,18 +19,52 @@ start_addr = 10
 with serial.Serial("/dev/ttyUSB0", 115200) as ser:
 
     payload = bytearray(512)
-    # payload.extend(channels)
-    payload[(start_addr - 1) : (start_addr - 1 + len(channels))] = channels
 
-    print(payload)
+    FPS = 20
+    FRAME_TIME = 1 / FPS
+    t = 0
+    
+    def sync():
+        # wait for sync
+        while True:
+            b = ser.readline()
+            if b.strip() == b"Sync.":
+                return
+            
+    sync()
+
+    print("initial sync.")
 
     while True:
+        
+        loop_start = time.time()
 
+        r, g, b = colorsys.hls_to_rgb(t, 0.5, 1)
+
+        channels[3] = int(255 * r)
+        channels[4] = int(255 * g)
+        channels[5] = int(255 * b)
+
+        payload[(start_addr - 1) : (start_addr - 1 + len(channels))] = channels
+        
         ser.write(payload)
         ser.flush()
+        
+        response = ser.readline()
+        if response.strip() != b"Ack.":
+            print(f"received bad response: {response!r}")
+            sync()
+            continue
 
-        time.sleep(1/50)
+        t += FRAME_TIME
+        t %= 1
+        
+        loop_time = time.time() - loop_start
+        if loop_time < FRAME_TIME:
+            time.sleep(FRAME_TIME - loop_time)
+        else:
+            print("loop took too long!")
+            
+        print(f"loop time: {1000 * loop_time:0.2f}ms busy, {1000 * (time.time() - loop_start):0.2f}ms total")
 
-        print(".")
+    # print(ser.read_all())
-
-    #print(ser.read_all())

microcontroller/test.ino

@@ -1,4 +1,7 @@
 unsigned long tic_loop = 0;
+unsigned long time_since_last_sync;
+const unsigned long SYNC_TIMEOUT = 1000;
+
 const unsigned int FRAME_TIME = 20; // 20 ms -> 50 FPS
 
 const size_t UNIVERSE_SIZE = 512;
@@ -15,7 +18,8 @@ void setup()
         // spin until serial is up
     }
     Serial.println();
-    Serial.println("Init.");
+    Serial.println("Sync.");
+    time_since_last_sync = millis();
 
     Serial1.begin(250000, SERIAL_8N2); // DMX
 }
@@ -38,19 +42,30 @@ void send_packet()
 
 bool update_buffer()
 {
+    unsigned long now = millis();
     size_t n = Serial.available();
     if (!n)
+    {
+        // nothing available to read
+        if (now - time_since_last_sync > SYNC_TIMEOUT)
+        {
+            // re-sync
+            bytes_read = 0;
+            Serial.println("Sync.");
+            time_since_last_sync = now;
+        }
+
         return false;
+    }
+    time_since_last_sync = now;
+
     int bytes_received = Serial.read(channels_buffer + bytes_read, std::min(n, UNIVERSE_SIZE - bytes_read));
     bytes_read += bytes_received;
 
-    // Serial.printf("rx n=%d rec=%d total=%d\n", n, bytes_received, bytes_read);
-
     if (bytes_read == UNIVERSE_SIZE)
     {
         bytes_read = 0;
-        // Serial.println();
+        Serial.println("Ack.");
-        // Serial.println("Updated.");
         return true;
     }
     else
@@ -63,18 +78,10 @@ void send_dmx_header()
 {
     Serial1.flush();
     Serial1.begin(90000, SERIAL_8N2);
-    /*
-    while (Serial1.available())
-        Serial1.read();
-    */
     // send the break as a "slow" byte
     Serial1.write(0);
     // switch back to the original baud rate
     Serial1.flush();
     Serial1.begin(250000, SERIAL_8N2);
-    /*
-    while (Serial1.available())
-        Serial1.read();
-    */
     Serial1.write(0); // Start-Byte
 }