Power-cycle-friendly Nano boot and ESP relay handling

Nano / driver: - No full on/off flip at boot; the first display() after boot is a forced full redraw instead, since the physical dot state is unknown - Send READY when booted ESP32: - relayOn() only switches and waits when the relay was off, and waits for the Nano's READY (3 s timeout) instead of a fixed 3 s on every frame - relayOff() ends Serial and releases the TX pin so the idle-high line no longer back-powers the Nano through its RX pin - No display commands are sent while the relay is off - Switching the relay on cancels a pending power-off countdown Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-13 00:12:28 +02:00
1 parent f7ffcf4ab3
commit 6e4d5e152b
@@ -26,7 +26,13 @@ BROSE9323 driver is built with `-D ESPSERIAL`, so every GFX call is sent over `S
  - `FlipDotDisplayClock`: clock on, or the Nintendo logo when off
  - `FlipDotDisplayPower`: turns the display off through the relay
 - **Relay on GPIO 13** switches the power for both the panels and the Nano. `LOW` turns it
-  on. After switching on, the ESP waits 3 s so the Nano can boot before frames are sent.
+  on.
+  - **On:** the ESP waits for the Nano's `READY` message, at most 3 s
+    (`NANO_BOOT_TIMEOUT`), before it sends frames. The relay stays on while it is needed;
+    the ESP only waits when it actually switches the relay on.
+  - **Off:** the ESP stops sending and releases its TX pin (`Serial.end()` and the pin set
+    to input). An idle UART line is high and would otherwise power the Nano through its RX
+    pin.
 - **Status LED** (built-in) blinks fast when WiFi is down and slowly when connected. It is
  off at night or when the display is powered off.

@@ -44,7 +44,11 @@ HASwitch powerSwitch("FlipDotDisplayPower");
 bool power = true;

 const int led1 = BUILTIN_LED; // Pin of the LED
-const int relay = 13; // Pin of the relay
+const int relay = 13; // Pin of the relay, powers the panels and the Nano (LOW = on)
+const int nano_tx = 1; // UART0 TX, wired to the Nano RX
+bool relay_on = false;
+// Max wait for the Nano's READY after power on (also the wait when Nano TX is not wired to our RX)
+const uint32_t NANO_BOOT_TIMEOUT = 3000;

 int hour = 0;
 int minute = 0;
@@ -5,6 +5,60 @@ void toggleLED(void *parameter);
 uint32_t power_off_delay;
 int triggered_power_off = false;
 int turn_hassio_power_off = false;
+
+// Wait until the Nano reports READY after booting, or until NANO_BOOT_TIMEOUT
+void waitForNano()
+{
+  char line[16];
+  uint8_t len = 0;
+  uint32_t start = millis();
+  while (millis() - start < NANO_BOOT_TIMEOUT)
+  {
+    while (Serial.available())
+    {
+      char c = Serial.read();
+      if (c == '\n')
+      {
+        line[len] = '\0';
+        if (strstr(line, "READY"))
+          return;
+        len = 0;
+      }
+      else if (len < sizeof(line) - 1)
+        line[len++] = c;
+    }
+    delay(10);
+  }
+}
+
+void relayOn()
+{
+  // cancel a pending power off countdown
+  triggered_power_off = false;
+
+  if (relay_on)
+    return;
+
+  Serial.begin(115200);
+  // drop old data (e.g. ERR replies) so only a new READY counts
+  while (Serial.available())
+    Serial.read();
+
+  digitalWrite(relay, LOW);
+  waitForNano();
+  relay_on = true;
+}
+
+void relayOff()
+{
+  digitalWrite(relay, HIGH);
+  relay_on = false;
+
+  // An idle UART TX line is high and would power the Nano through its RX pin
+  Serial.flush();
+  Serial.end();
+  pinMode(nano_tx, INPUT);
+}
 void turnPowerOff(uint32_t delay = 30000, bool _turn_hassio_power_off = false)
 {
    if(triggered_power_off == false)
@@ -25,7 +79,7 @@ void updatePower()
        triggered_power_off = false;

        // OFF
-        digitalWrite(relay, HIGH);
+        relayOff();

        if(turn_hassio_power_off)
        {
@@ -46,10 +100,13 @@ void onPowerSwitchStateChanged(bool state, HASwitch *s)

  if(power == false)
  {
-      display.fillScreen(0);
-      display.display();
+      if (relay_on)
+      {
+        display.fillScreen(0);
+        display.display();

-      delay(1000);
+        delay(1000);
+      }

      turnPowerOff(0);
    
@@ -230,9 +287,7 @@ void setup()
  otaPanicMode = false;

  pinMode(relay, OUTPUT);
-  digitalWrite(relay, LOW);
-
-  delay(4000);
+  relayOn();

  display.begin(&Serial);
  // display.setTiming(200);
@@ -379,11 +434,7 @@ void drawRotatedBitmap(int16_t x, int16_t y, const uint8_t *bitmap, int16_t w, i
 void turnPowerOn(bool overide = false)
 {
  if(power == true || overide == true)
-  {
-    // ON
-    digitalWrite(relay, LOW);
-    delay(3000);
-  }
+    relayOn();
 }

 void loop()
@@ -434,8 +485,11 @@ void loop()
    
      if(hour <= 7 || (hour >= 23 && minute > 30))
      {
-        display.fillScreen(0);
-        display.display();
+        if (relay_on)
+        {
+          display.fillScreen(0);
+          display.display();
+        }

        turnPowerOff();
      }
@@ -446,28 +500,32 @@ void loop()
      {
        turnPowerOn();

-        int xoffset = 3;
+        // power can be off (Home Assistant power switch): then nothing is sent
+        if (relay_on)
+        {
+          int xoffset = 3;

-        display.fillScreen(0);
-        // display.setTextSize(2);
-        display.setTextSize(1);
-        // display.setCursor(7, 3);
-        display.setCursor(xoffset + 0, 19 - 2);
-        display.setTextWrap(false);
-        // display.print(t);
+          display.fillScreen(0);
+          // display.setTextSize(2);
+          display.setTextSize(1);
+          // display.setCursor(7, 3);
+          display.setCursor(xoffset + 0, 19 - 2);
+          display.setTextWrap(false);
+          // display.print(t);

-        // if(minute % 2 == 0)
-        if(hour >= 17 || hour <= 6)
-          display.drawBitmap(xoffset + 0, 0, yawning_pikachu_bitmap_yawning_pikachu_black_border, 35, 19, 1);
-        else
-          display.drawBitmap(xoffset + 0, 0, pikachu_bitmap_pikachu_black_border, 35, 19, 1);
+          // if(minute % 2 == 0)
+          if(hour >= 17 || hour <= 6)
+            display.drawBitmap(xoffset + 0, 0, yawning_pikachu_bitmap_yawning_pikachu_black_border, 35, 19, 1);
+          else
+            display.drawBitmap(xoffset + 0, 0, pikachu_bitmap_pikachu_black_border, 35, 19, 1);

-        display.drawBitmap(xoffset + 35, 0, clock_thought_bubble_bitmap_clock_thought_bubble, 46, 19, 1);
+          display.drawBitmap(xoffset + 35, 0, clock_thought_bubble_bitmap_clock_thought_bubble, 46, 19, 1);
        
-        display.setCursor(xoffset + 43, (19/2) - 5);
-        display.print(timeStringBuff);
+          display.setCursor(xoffset + 43, (19/2) - 5);
+          display.print(timeStringBuff);
      
-        display.display();
+          display.display();
+        }
      }
      else
      {
@@ -476,34 +534,37 @@ void loop()
    }
    else
    {
-      display.fillScreen(0);
-      display.drawBitmap(0, 0, nintendo_bitmap_Nintendo_new, 84, 19, 1);
+      if (relay_on)
+      {
+        display.fillScreen(0);
+        display.drawBitmap(0, 0, nintendo_bitmap_Nintendo_new, 84, 19, 1);

-      // display.drawBitmap(0, 0, nintendo_bitmap_panda_inverted, 17, 18, 1);
-      // display.drawBitmap(18, 0, nintendo_bitmap_panda_inverted, 17, 18, 1);
-      // display.drawBitmap(18*2, 0, nintendo_bitmap_panda_inverted, 17, 18, 1);
-      // display.drawBitmap(18*3, 0, nintendo_bitmap_panda_inverted, 17, 18, 1);
-      // display.drawBitmap(18*4, 0, nintendo_bitmap_panda_inverted, 17, 18, 1);
+        // display.drawBitmap(0, 0, nintendo_bitmap_panda_inverted, 17, 18, 1);
+        // display.drawBitmap(18, 0, nintendo_bitmap_panda_inverted, 17, 18, 1);
+        // display.drawBitmap(18*2, 0, nintendo_bitmap_panda_inverted, 17, 18, 1);
+        // display.drawBitmap(18*3, 0, nintendo_bitmap_panda_inverted, 17, 18, 1);
+        // display.drawBitmap(18*4, 0, nintendo_bitmap_panda_inverted, 17, 18, 1);

-      // drawRotatedBitmap(0, 0, nintendo_bitmap_Nintendo_new, 17, 18, 1, 90);
+        // drawRotatedBitmap(0, 0, nintendo_bitmap_Nintendo_new, 17, 18, 1, 90);

-      // Text inside border.
-      // display.drawBitmap(0, 0, nintendo_bitmap_nintendo_border, 84, 19, 1);
-      // display.setFont();
-      // display.setTextSize(1);
-      // display.setTextWrap(false);
-      // display.setCursor(5, 4);
-      // display.print("Nintendo");
+        // Text inside border.
+        // display.drawBitmap(0, 0, nintendo_bitmap_nintendo_border, 84, 19, 1);
+        // display.setFont();
+        // display.setTextSize(1);
+        // display.setTextWrap(false);
+        // display.setCursor(5, 4);
+        // display.print("Nintendo");

-      // display.setFont();
-      // // display.setTextSize(2);
-      // display.setTextSize(1);
-      //  display.setCursor(0, 0);
-      // display.setTextWrap(true);
-      // // display.print(t);
-      // display.print("Carla & Jan   Kragt");
+        // display.setFont();
+        // // display.setTextSize(2);
+        // display.setTextSize(1);
+        //  display.setCursor(0, 0);
+        // display.setTextWrap(true);
+        // // display.print(t);
+        // display.print("Carla & Jan   Kragt");

-      display.display();
+        display.display();
+      }

      turnPowerOff();
    }