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mcu/wwvb-ref/wwvb-ref.ino
sneak 2d9aa994a8 initial
2022-01-11 02:08:04 -08:00

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/* WWVB Clock v 1.0
*
* A WWVB (NIST Time Code Broadcast) receiving clock powered by an
* Arduino (ATMega328), a DS1307 Real Time Clock, and a C-Max
* C-Max CMMR-6P-60 WWVB receiver module.
*
* This code builds on Capt.Tagon's code at duinolab.blogspot.com
* which was a great reference. Specifically, I used almost without change
* his struct / unsigned long long overlay for the received WWVB Buffer,
* which apparently in turn draws on DCF77 decoding code by Rudi Niemeijer,
* Mathias Dalheimer, and "Captain."
*
* The RTC (DS1307) interface code builds in part on code by
* Jon McPhalen (www.jonmcphalen.com)
*
* There you have it.
*
* This code supports the "Atomic Clock" article in the April 2010 issue
* of Popular Science. There is also a schematic for this project. There
* is also WWVB signal simulator code, to facilitate debugging and
* hacking on this project when the reception of the WWVB signal
* itself is less than stellar.
*
* The code for both the clock and the WWVB simulator, and the schematic
* are available online at:
* http://www.popsci.com/diy/article/2010-03/build-clock-uses-atomic-timekeeping
*
* and on GitHub at: http://github.com/vinmarshall/WWVB-Clock
*
* Version 1.0
* Notes:
* - No timezone support in this version. UTC only.
* - No explicit leapsecond (3 frame marker bits) support in this version.
* - 24 hour mode only
*
*
* Copyright (c) 2010 Vin Marshall (vlm@2552.com, www.2552.com)
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
*/
#define SERIAL_RATE 115200
#define WWV_SIGNAL_PIN 14
#define PPS_OUTPUT_PIN 16
#define DEBUG1_OUTPUT_PIN 15
#include <stdio.h>
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27, 16, 2);
void ICACHE_RAM_ATTR wwvbChange();
//
// Initializations
// Debugging mode - prints debugging information on the Serial port.
boolean debug = true;
// Front Panel Light
int lightPin = LED_BUILTIN;
// WWVB Receiver Pin
int wwvbInPin = WWV_SIGNAL_PIN;
// LCD init
//LiquidCrystal lcd(12, 11, 6, 5, 4, 3);
// RTC init
// RTC uses pins Analog4 = SDA, Analog5 = SCL
// RTC I2C Slave Address
#define DS1307 0xD0 >> 1
// RTC Memory Registers
#define RTC_SECS 0
#define RTC_MINS 1
#define RTC_HRS 2
#define RTC_DAY 3
#define RTC_DATE 4
#define RTC_MONTH 5
#define RTC_YEAR 6
#define RTC_SQW 7
// Month abbreviations
char *months[12] = {
"Jan",
"Feb",
"Mar",
"Apr",
"May",
"Jun",
"Jul",
"Aug",
"Sep",
"Oct",
"Nov",
"Dec"
};
// Day of Year to month translation (thanks to Capt.Tagon)
// End of Month - to calculate Month and Day from Day of Year
int eomYear[14][2] = {
{0,0}, // Begin
{31,31}, // Jan
{59,60}, // Feb
{90,91}, // Mar
{120,121}, // Apr
{151,152}, // May
{181,182}, // Jun
{212,213}, // Jul
{243,244}, // Aug
{273,274}, // Sep
{304,305}, // Oct
{334,335}, // Nov
{365,366}, // Dec
{366,367} // overflow
};
//
// Globals
// Timing and error recording
unsigned long pulseStartTime = 0;
unsigned long pulseEndTime = 0;
unsigned long frameEndTime = 0;
unsigned long lastRtcUpdateTime = 0;
boolean bitReceived = false;
boolean wasMark = false;
int framePosition = 0;
int bitPosition = 1;
char lastTimeUpdate[17];
char lastBit = ' ';
int errors[10] = { 1,1,1,1,1,1,1,1,1,1 };
int errIdx = 0;
int bitError = 0;
boolean frameError = false;
// RTC clock variables
byte second = 0x00;
byte minute = 0x00;
byte hour = 0x00;
byte day = 0x00;
byte date = 0x01;
byte month = 0x01;
byte year = 0x00;
byte ctrl = 0x00;
// WWVB time variables
byte wwvb_hour = 0;
byte wwvb_minute = 0;
byte wwvb_day = 0;
byte wwvb_year = 0;
/* WWVB time format struct - acts as an overlay on wwvbRxBuffer to extract time/date data.
* This points to a 64 bit buffer wwvbRxBuffer that the bits get inserted into as the
* incoming data stream is received. (Thanks to Capt.Tagon @ duinolab.blogspot.com)
*/
struct wwvbBuffer {
unsigned long long U12 :4; // no value, empty four bits only 60 of 64 bits used
unsigned long long Frame :2; // framing
unsigned long long Dst :2; // dst flags
unsigned long long Leapsec :1; // leapsecond
unsigned long long Leapyear :1; // leapyear
unsigned long long U11 :1; // no value
unsigned long long YearOne :4; // year (5 -> 2005)
unsigned long long U10 :1; // no value
unsigned long long YearTen :4; // year (5 -> 2005)
unsigned long long U09 :1; // no value
unsigned long long OffVal :4; // offset value
unsigned long long U08 :1; // no value
unsigned long long OffSign :3; // offset sign
unsigned long long U07 :2; // no value
unsigned long long DayOne :4; // day ones
unsigned long long U06 :1; // no value
unsigned long long DayTen :4; // day tens
unsigned long long U05 :1; // no value
unsigned long long DayHun :2; // day hundreds
unsigned long long U04 :3; // no value
unsigned long long HourOne :4; // hours ones
unsigned long long U03 :1; // no value
unsigned long long HourTen :2; // hours tens
unsigned long long U02 :3; // no value
unsigned long long MinOne :4; // minutes ones
unsigned long long U01 :1; // no value
unsigned long long MinTen :3; // minutes tens
};
struct wwvbBuffer * wwvbFrame;
unsigned long long receiveBuffer;
unsigned long long lastFrameBuffer;
/*
* setup()
*
* uC Initialization
*/
void setup() {
Serial.begin(SERIAL_RATE);
Serial.println("*****************************************");
Serial.println("*****************************************");
Serial.println("*****************************************");
Serial.print("*** ESP8266 Ready.\n");
// Initialize the I2C Two Wire Communication for the RTC
//Wire.begin();
lcd.init();
lcd.backlight();
lcd.setCursor(0, 0);
lcd.print("booting");
// Setup the light pin
pinMode(lightPin, OUTPUT);
digitalWrite(lightPin, LOW);
pinMode(DEBUG1_OUTPUT_PIN, OUTPUT);
// Print a message to the LCD.
lcd.clear();
lcd.setCursor(0, 0);
lcd.print("WWVB Clock v 1.0");
lcd.setCursor(0, 1);
lcd.print("PopSci Apr. 2010");
delay(5000);
// Front panel light lights for 10 seconds on a successful frame rcpt.
digitalWrite(lightPin, HIGH);
// Setup the WWVB Signal In Handling
pinMode(wwvbInPin, INPUT);
attachInterrupt(0, wwvbChange, CHANGE);
// Setup the WWVB Buffer
lastFrameBuffer = 0;
receiveBuffer = 0;
wwvbFrame = (struct wwvbBuffer *) &lastFrameBuffer;
Serial.println("*** setup() complete");
}
/*
* loop()
*
* Main program loop
*/
void loop() {
// If we've received another bit, process it
if (bitReceived == true) {
Serial.println("*** bitReceived==true");
processBit();
}
// Read from the RTC and update the display 4x per second
if (millis() - lastRtcUpdateTime > 250) {
// Snag the RTC time and store it locally
//getRTC();
// And record the time of this last update.
lastRtcUpdateTime = millis();
// Update RTC if there has been a successfully received WWVB Frame
if (frameEndTime != 0) {
//updateRTC();
frameEndTime = 0;
}
// Update the display
updateDisplay();
}
}
/*
* updateDisplay()
*
* Update the 2 line x 16 char LCD display
*/
void updateDisplay() {
// Turn off the front panel light marking a successfully
// received frame after 10 seconds of being on.
if (bcd2dec(second) >= 10) {
digitalWrite(lightPin, HIGH);
}
// Update the LCD
lcd.clear();
// Update the first row
lcd.setCursor(0,0);
char *time = buildTimeString();
lcd.print(time);
// Update the second row
// Cycle through our list of status messages
lcd.setCursor(0,1);
int cycle = bcd2dec(second) / 10; // This gives us 6 slots for messages
char msg[17]; // 16 chars per line on display
switch (cycle) {
// Show the Date
case 0:
{
sprintf(msg, "%s %0.2i 20%0.2i",
months[bcd2dec(month)-1], bcd2dec(date), bcd2dec(year));
break;
}
// Show the WWVB signal strength based on the # of recent frame errors
case 1:
{
int signal = (10 - sumFrameErrors()) / 2;
sprintf(msg, "WWVB Signal: %i", signal);
break;
}
// Show LeapYear and LeapSecond Warning bits
case 2:
{
const char *leapyear = ( ((byte) wwvbFrame->Leapyear) == 1)?"Yes":"No";
const char *leapsec = ( ((byte) wwvbFrame->Leapsec) == 1)?"Yes":"No";
sprintf(msg, "LY: %s LS: %s", leapyear, leapsec);
break;
}
// Show our Daylight Savings Time status
case 3:
{
switch((byte)wwvbFrame->Dst) {
case 0:
sprintf(msg, "DST: No");
break;
case 1:
sprintf(msg, "DST: Ending");
break;
case 2:
sprintf(msg, "DST: Starting");
break;
case 3:
sprintf(msg, "DST: Yes");
break;
}
break;
}
// Show the UT1 correction sign and amount
case 4:
{
char sign;
if ((byte)wwvbFrame->OffSign == 2) {
sign = '-';
} else if ((byte)wwvbFrame->OffSign == 5) {
sign = '+';
} else {
sign = '?';
}
sprintf(msg, "UT1 %c 0.%i", sign, (byte) wwvbFrame->OffVal);
break;
}
// Show the time and date of the last successfully received
// wwvb frame
case 5:
{
sprintf(msg, "[%s]", lastTimeUpdate);
break;
}
}
lcd.print(msg);
}
/*
* buildTimeString
*
* Prepare the string for displaying the time on line 1 of the LCD
*/
char* buildTimeString() {
char rv[255];
sprintf(rv,"%0.2i:%0.2i:%0.2i UTC %c",
bcd2dec(hour),
bcd2dec(minute),
bcd2dec(second),
lastBit);
return rv;
}
/*
* getRTC
*
* Read data from the DS1307 RTC over the I2C 2 wire interface.
* Data is stored in the uC's global clock variables.
*/
/*
void getRTC() {
// Begin the Transmission
Wire.beginTransmission(DS1307);
// Point the request at the first register (seconds)
Wire.write(RTC_SECS);
// End the Transmission and Start Listening
Wire.endTransmission();
Wire.requestFrom(DS1307, 8);
second = Wire.receive();
minute = Wire.receive();
hour = Wire.receive();
day = Wire.receive();
date = Wire.receive();
month = Wire.receive();
year = Wire.receive();
ctrl = Wire.receive();
}
*/
/*
* setRTC
*
* Set the DS1307 RTC over the I2C 2 wire interface.
* Data is read from the uC's global clock variables.
*/
/*
void setRTC() {
// Begin the Transmission
Wire.beginTransmission(DS1307);
// Start at the beginning
Wire.write(RTC_SECS);
// Send data for each register in order
Wire.write(second);
Wire.write(minute);
Wire.write(hour);
Wire.send(day);
Wire.send(date);
Wire.send(month);
Wire.send(year);
Wire.send(ctrl);
// End the transmission
Wire.endTransmission();
}
*/
/*
* updateRTC
*
* Update the time stored in the RTC to match the received WWVB frame.
*/
/*
void updateRTC() {
// Find out how long since the frame's On Time Marker (OTM)
// We'll need this adjustment when we set the time.
unsigned int timeSinceFrame = millis() - frameEndTime;
byte secondsSinceFrame = timeSinceFrame / 1000;
if (timeSinceFrame % 1000 > 500) {
secondsSinceFrame++;
}
// The OTM for a minute comes at the beginning of the frame, meaning that
// the WWVB time we have is now 1 minute + `secondsSinceFrame` seconds old.
incrementWwvbMinute();
// Set up data for the RTC clock write
second = secondsSinceFrame;
minute = ((byte) wwvbFrame->MinTen << 4) + (byte) wwvbFrame->MinOne;
hour = ((byte) wwvbFrame->HourTen << 4) + (byte) wwvbFrame->HourOne;
day = 0; // we're not using day of week at this time.
// Translate wwvb day of year into a month and a day of month
// This routine is courtesy of Capt.Tagon
int doy = ((byte) wwvbFrame->DayHun * 100) +
((byte) wwvbFrame->DayTen * 10) +
((byte) wwvbFrame->DayOne);
int i = 0;
byte isLeapyear = (byte) wwvbFrame->Leapyear;
while ( (i < 14) && (eomYear[i][isLeapyear] < doy) ) {
i++;
}
if (i>0) {
date = dec2bcd(doy - eomYear[i-1][isLeapyear]);
month = dec2bcd((i > 12)?1:i);
}
year = ((byte) wwvbFrame->YearTen << 4) + (byte) wwvbFrame->YearOne;
// And write the update to the RTC
//setRTC();
// Store the time of update for the display status line
sprintf(lastTimeUpdate, "%0.2i:%0.2i %0.2i/%0.2i/%0.2i",
bcd2dec(hour), bcd2dec(minute), bcd2dec(month),
bcd2dec(date), bcd2dec(year));
}
*/
/*
* processBit()
*
* Decode a received pulse. Pulses are decoded according to the
* length of time the pulse was in the low state.
*/
void processBit() {
Serial.println("*** in processBit()");
char buf[255];
// Clear the bitReceived flag, as we're processing that bit.
bitReceived = false;
// determine the width of the received pulse
unsigned int pulseWidth = pulseEndTime - pulseStartTime;
sprintf(buf,"got bit with pulseWidth=%d\n",pulseWidth);
Serial.print(buf);
// Attempt to decode the pulse into an Unweighted bit (0),
// a Weighted bit (1), or a Frame marker.
// Pulses < 0.2 sec are an error in reception.
if (pulseWidth < 100) {
buffer(-2);
bitError++;
wasMark = false;
// 0.2 sec pulses are an Unweighted bit (0)
} else if (pulseWidth < 400) {
buffer(0);
wasMark = false;
// 0.5 sec pulses are a Weighted bit (1)
} else if (pulseWidth < 700) {
buffer(1);
wasMark = false;
// 0.8 sec pulses are a Frame Marker
} else if (pulseWidth < 900) {
// Two Frame Position markers in a row indicate an
// end/beginning of frame marker
if (wasMark) {
// For the display update
lastBit = '*';
Serial.println("*** Frame Start");
// Verify that our position data jives with this being
// a Frame start/end marker
if ( (framePosition == 6) &&
(bitPosition == 60) &&
(bitError == 0)) {
// Process a received frame
frameEndTime = pulseStartTime;
lastFrameBuffer = receiveBuffer;
digitalWrite(lightPin, LOW);
logFrameError(false);
debugPrintFrame();
} else {
frameError = true;
}
// Reset the position counters
framePosition = 0;
bitPosition = 1;
wasMark = false;
bitError = 0;
receiveBuffer = 0;
// Otherwise, this was just a regular frame position marker
} else {
buffer(-1);
wasMark = true;
}
// Pulses > 0.8 sec are an error in reception
} else {
buffer(-2);
bitError++;
wasMark = false;
}
// Reset everything if we have more than 60 bits in the frame. This means
// the frame markers went missing somewhere along the line
if (frameError == true || bitPosition > 60) {
// Debugging
Serial.println("*** Frame Error");
// Reset all of the frame pointers and flags
frameError = false;
logFrameError(true);
framePosition = 0;
bitPosition = 1;
wasMark = false;
bitError = 0;
receiveBuffer = 0;
}
}
/*
* logFrameError
*
* Log the error in the buffer that is a window on the past 10 frames.
*/
void logFrameError(boolean err) {
// Add a 1 to log errors to the buffer
int add = err?1:0;
errors[errIdx] = add;
// and move the buffer loop-around pointer
if (++errIdx >= 10) {
errIdx = 0;
}
}
/*
* sumFrameErrors
*
* Turn the errors in the frame error buffer into a number useful to display
* the quality of reception of late in the status messages. Sums the errors
* in the frame error buffer.
*/
int sumFrameErrors() {
// Sum all of the values in our error buffer
int i, rv;
for (i=0; i< 10; i++) {
rv += errors[i];
}
return rv;
}
/*
* debugPrintFrame
*
* Print the decoded frame over the seriail port
*/
void debugPrintFrame() {
char time[255];
byte minTen = (byte) wwvbFrame->MinTen;
byte minOne = (byte) wwvbFrame->MinOne;
byte hourTen = (byte) wwvbFrame->HourTen;
byte hourOne = (byte) wwvbFrame->HourOne;
byte dayHun = (byte) wwvbFrame->DayHun;
byte dayTen = (byte) wwvbFrame->DayTen;
byte dayOne = (byte) wwvbFrame->DayOne;
byte yearOne = (byte) wwvbFrame->YearOne;
byte yearTen = (byte) wwvbFrame->YearTen;
byte wwvb_minute = (10 * minTen) + minOne;
byte wwvb_hour = (10 * hourTen) + hourOne;
byte wwvb_day = (100 * dayHun) + (10 * dayTen) + dayOne;
byte wwvb_year = (10 * yearTen) + yearOne;
sprintf(time, "\nFrame Decoded: %0.2i:%0.2i %0.3i 20%0.2i\n",
wwvb_hour, wwvb_minute, wwvb_day, wwvb_year);
Serial.print(time);
}
/*
* buffer
*
* Places the received bits in the receive buffer in the order they
* were recived. The first received bit goes in the highest order
* bit of the receive buffer.
*/
void buffer(int bit) {
// Process our bits
if (bit == 0) {
lastBit = '0';
if (debug) { Serial.println("0"); }
} else if (bit == 1) {
lastBit = '1';
if (debug) { Serial.println("1"); }
} else if (bit == -1) {
lastBit = 'M';
if (debug) { Serial.println("M"); }
framePosition++;
} else if (bit == -2) {
lastBit = 'X';
if (debug) { Serial.println("X"); }
}
// Push the bit into the buffer. The 0s and 1s are the only
// ones we care about.
if (bit < 0) { bit = 0; }
receiveBuffer = receiveBuffer | ( (unsigned long long) bit << (64 - bitPosition) );
// And increment the counters that keep track of where we are
// in the frame.
bitPosition++;
}
/*
* incrementWwvbMinute
*
* The frame On Time Marker occurs at the beginning of the frame. This means
* that the time in the frame is one minute old by the time it has been fully
* received. Adding one to the minute can be somewhat complicated, in as much
* as it can roll over the successive hours, days, and years in just the right
* circumstances. This handles that.
*/
void incrementWwvbMinute() {
// Increment the Time and Date
if (++(wwvbFrame->MinOne) == 10) {
wwvbFrame->MinOne = 0;
wwvbFrame->MinTen++;
}
if (wwvbFrame->MinTen == 6) {
wwvbFrame->MinTen = 0;
wwvbFrame->HourOne++;
}
if (wwvbFrame->HourOne == 10) {
wwvbFrame->HourOne = 0;
wwvbFrame->HourTen++;
}
if ( (wwvbFrame->HourTen == 2) && (wwvbFrame->HourOne == 4) ) {
wwvbFrame->HourTen = 0;
wwvbFrame->HourOne = 0;
wwvbFrame->DayOne++;
}
if (wwvbFrame->DayOne == 10) {
wwvbFrame->DayOne = 0;
wwvbFrame->DayTen++;
}
if (wwvbFrame->DayTen == 10) {
wwvbFrame->DayTen = 0;
wwvbFrame->DayHun++;
}
if ( (wwvbFrame->DayHun == 3) &&
(wwvbFrame->DayTen == 6) &&
(wwvbFrame->DayOne == (6 + (int) wwvbFrame->Leapyear)) ) {
// Happy New Year.
wwvbFrame->DayHun = 0;
wwvbFrame->DayTen = 0;
wwvbFrame->DayOne = 1;
wwvbFrame->YearOne++;
}
if (wwvbFrame->YearOne == 10) {
wwvbFrame->YearOne = 0;
wwvbFrame->YearTen++;
}
if (wwvbFrame->YearTen == 10) {
wwvbFrame->YearTen = 0;
}
}
/*
* wwvbChange
*
* This is the interrupt servicing routine. Changes in the level of the
* received WWVB pulse are recorded here to be processed in processBit().
*/
void wwvbChange() {
digitalWrite(DEBUG1_OUTPUT_PIN, HIGH);
int signalLevel = digitalRead(wwvbInPin);
// Determine if this was triggered by a rising or a falling edge
// and record the pulse low period start and stop times
//FIXME this might need to be HIGH
if (signalLevel == HIGH) {
pulseStartTime = millis();
} else {
pulseEndTime = millis();
bitReceived = true;
}
digitalWrite(DEBUG1_OUTPUT_PIN, LOW);
}
/*
* bcd2dec
*
* Utility function to convert 2 bcd coded hex digits into an integer
*/
int bcd2dec(int bcd) {
return ( (bcd>>4) * 10) + (bcd % 16);
}
/*
* dec2bcd
*
* Utility function to convert an integer into 2 bcd coded hex digits
*/
int dec2bcd(int dec) {
return ( (dec/10) << 4) + (dec % 10);
}
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