refactor: Integrate intelligent market-driven deep sleep

m5paper-stockticker.ino

@@ -326,6 +326,11 @@ void setup() {
   struct tm now = {};
   for (int i = 0; i < 10 && !getLocalTime(&now); i++) delay(500);
 
+  // Current US Eastern time -> tells us which event (open/mid/close) this is
+  // and, later, when the next event is.
+  struct tm etTm;
+  getEasternTime(etTm);
+
   // Fetch market data
   StockData sd[NUM_STOCKS];
   float dayGain = 0.0f, openValue = 0.0f;
@@ -351,10 +356,11 @@ void setup() {
 
   // -- Row 1: timestamp (left)  |  "zZz [battery] xx%" (right) --
   char timeStr[32];
-  strftime(timeStr, sizeof(timeStr), "%d/%m %I:%M %p", &now);
+  strftime(timeStr, sizeof(timeStr), "%m/%d %I:%M %p", &now);
   M5.Display.setCursor(20, 22);
   M5.Display.print("U: ");
   M5.Display.print(timeStr);
+  M5.Display.printf("  (%s)", marketPhase(etTm));
 
   M5.Display.setCursor(740, 15);
   M5.Display.print("zZz");
@@ -418,7 +424,9 @@ void setup() {
   M5.Display.endWrite();
 
   delay(1000);
-  M5.Power.deepSleep(43200000000ULL); // 12 hours
+  // We wake at open, midday, and close, so update now and sleep until
+  // whichever event comes next (Mon-Fri).
+  prepareForSleepAndEnter(usUntilNextEvent(etTm));
 }
 
 void loop() {}