From: Art Cancro <ajc@citadel.org>
Date: Fri, 10 Nov 2023 05:30:43 +0000 (-0500)
Subject: Reduced hysteresis to 3 samples.  Expanded valid pulse width range.
X-Git-Url: https://code.citadel.org/?p=the_perfect_clock.git;a=commitdiff_plain;h=HEAD

Reduced hysteresis to 3 samples.  Expanded valid pulse width range.
---

diff --git a/the_perfect_clock.ino b/the_perfect_clock.ino
index d437e39..2529492 100644
--- a/the_perfect_clock.ino
+++ b/the_perfect_clock.ino
@@ -87,27 +87,9 @@ void setup() {
 // Note: only write to the display when the readout needs to be updated.
 // Speaking I2C on every loop iteration jams the WWVB receiver.
 void loop() {
-  int signal;
-  static int total_samples = 0;
-  static int high_samples = 0;
-
-  // read from the WWVB receiver, with some hysteresis
-  if (total_samples >= 100) {
-    if (high_samples > 20) {
-      signal = HIGH;
-    }
-    else {
-      signal = LOW;
-    }
-    total_samples = 0;
-    high_samples = 0;
-  }
-  else {
-    total_samples += 1;
-    if (digitalRead(wwvb) == HIGH) {
-      ++high_samples;
-    }
-  }
+
+  // Reading it three times and taking the average gives us some hysteresis
+  int signal = (digitalRead(wwvb) + digitalRead(wwvb) + digitalRead(wwvb)) / 3;
 
   // has the timer ticked?
 	unsigned long m = millis();
@@ -142,13 +124,13 @@ void loop() {
 	else if ((!signal) && (previous_signal)) {		// trailing edge of pulse detected
 		pulse_length = millis() - start_of_pulse;
 
-		if (pulse_length > 175 && pulse_length < 225) {	// "0" bit ~= 200 ms (represented as "0")
+		if (pulse_length > 150 && pulse_length < 250) {	// "0" bit ~= 200 ms (represented as "0")
 			this_pulse = 0;
 		}
-		else if (pulse_length > 475 && pulse_length < 525) {	// "1" bit ~= 500 ms (represented as "1")
+		else if (pulse_length > 450 && pulse_length < 550) {	// "1" bit ~= 500 ms (represented as "1")
 			this_pulse = 1;
 		}
-		else if (pulse_length > 775 && pulse_length < 825) {	// marker bit ~= 800 ms (represented as "2")
+		else if (pulse_length > 750 && pulse_length < 850) {	// marker bit ~= 800 ms (represented as "2")
 			this_pulse = 2;
 		}
 		else {