Add periodic NTP resync

main.py

@@ -1,11 +1,25 @@
+
+import ntptime
+import esp
 from time import sleep, localtime
 from machine import Pin, Timer
 
+TIMEZONE = 3
+RESYNC = 7200 # Resync once in two hours
+
+print("Press Ctrl-C now abort main.py execution and to retain keyboard input")
+sleep(1)
+
+# Configure powersave
+esp.sleep_type(esp.SLEEP_LIGHT)
+
+# Note that keyboard input is lost beyond this point!
 clock = Pin(3, mode=Pin.OUT)
 latch = Pin(0, mode=Pin.OUT)
 data = Pin(2, mode=Pin.OUT)
 blink = 0
 lookup = 11, 9, 12, 8, 0, 4, 1, 3, 2, 10
+countdown = 0
 
 def bitbang_bit(value):
     if value & 1:
@@ -17,7 +31,7 @@ def bitbang_bit(value):
 
 def bitbang_digit(digit):
     bitbang_bit(blink)
-    for i in range(0,width):
+    for i in range(0,4):
         bitbang_bit(lookup[digit] << i >> 3)
     bitbang_bit(blink)
     bitbang_bit(blink)
@@ -26,12 +40,19 @@ def bitbang_digit(digit):
 timer = Timer(-1)
 
 def schedule(delay=0):
+    global countdown
+    if countdown <= 0:
+        ntptime.settime()
+        countdown = RESYNC
+        print("Resync")
+    countdown -= 1
     if delay:
         timer.init(period=1000, mode=Timer.ONE_SHOT, callback=dump)
     else:
         dump()
 
 def dump_time(hour, minute, second):
+    print("Time is %02d:%02d:%02d" % (hour, minute, second))
     bitbang_digit(hour // 10)
     bitbang_digit(hour % 10)
     bitbang_digit(minute // 10)
@@ -42,7 +63,7 @@ def dump_time(hour, minute, second):
 def dump(t=None):
     global blink
     year, month, day, hour, minute, second, _, millis = localtime()
-    dump_time((hour + 3) % 24, minute, second)
+    dump_time((hour + TIMEZONE) % 24, minute, second)
     latch.on()
     latch.off()
     blink = 1-blink