Use double buffer

terminal/puzzle_colorFade/potiNano/src/main.cpp

@@ -1,29 +1,39 @@
 #include <Arduino.h>
-
 #include <Wire.h>
 
 #define I2C_SLAVE_ADDRESS 0x08
 
-uint16_t values[6] = {0};
+volatile uint16_t bufferA[6];
+volatile uint16_t bufferB[6];
+
+// Pointer to the buffer currently exposed to ISR
+volatile uint16_t* activeBuffer = bufferA;
 
 void onI2CRequest() {
-    Wire.write((uint8_t*)values, sizeof(values));
+    // Safe: ISR only reads active buffer
+    Wire.write((uint8_t*)activeBuffer, 6 * sizeof(uint16_t));
 }
 
 void setup() {
     Wire.begin(I2C_SLAVE_ADDRESS);
     Wire.onRequest(onI2CRequest);
-
     analogReference(DEFAULT);
 }
 
 void loop() {
-    values[0] = analogRead(A0);
-    values[1] = analogRead(A1);
-    values[2] = analogRead(A2);
+    // Choose the inactive buffer
+    volatile uint16_t* writeBuffer =
+        (activeBuffer == bufferA) ? bufferB : bufferA;
 
-    values[3] = analogRead(A3);
-    values[4] = analogRead(A6);
-    values[5] = analogRead(A7);
-    delay(50);
+    writeBuffer[0] = analogRead(A0);
+    writeBuffer[1] = analogRead(A1);
+    writeBuffer[2] = analogRead(A2);
+    writeBuffer[3] = analogRead(A3);
+    writeBuffer[4] = analogRead(A6);
+    writeBuffer[5] = analogRead(A7);
+
+    // Atomic pointer swap
+    noInterrupts();
+    activeBuffer = writeBuffer;
+    interrupts();
 }