I have a working code for syncing the input to the output. (like a tentikal) Pulling pin 2 down to ground will set the sync.
Here is my code. (could be written better I think)
/*
Linear Timecode generation and decoding combined
Please modify as needed
(c) Frank B, 2020
(pls keep copyright-info)
To enable decoding:
#define USE_LTC_INPUT
and connect pin1 to pinA2 (=pin 16) !!!! I see no use to do this ????
PIN 2 : if set low it will sync incoming TC to the output TC . Then you can disconnect input TC and output will continue
Licence: MIT
*/
bool insync=0;
int incominghours=0;
int incomingminutes=0;
int incomingseconds=0;
int incomingframes=0;
#define USE_LTC_INPUT //comment-out for generation only
float fps = 25;
const int ltcPin = 1;
const int syncPin = 0;
#include "TimeLib.h"
#ifdef USE_LTC_INPUT
/*
Connect ltc
*/
#include <Audio.h>
#include <analyze_ltc.h>
AudioInputAnalog adc1;
AudioAnalyzeLTC ltc1;
AudioConnection patchCord2(adc1, 0, ltc1, 0);
#else
struct ltcframe_t {
uint64_t data;
uint16_t sync;
};
#endif
IntervalTimer ltcTimer;
IntervalTimer fpsTimer;
volatile int clkCnt = 0;
ltcframe_t ltc;
float ltcTimer_freq;
time_t getTeensy3Time()
{
return Teensy3Clock.get();
}
void genLtc() {
static int state = 0;
if (clkCnt++ >= 2 * 80) {
//ltcTimer.end();
clkCnt = 0;
return;
}
int bitval;
int bitcount = clkCnt / 2;
ltcframe_t ltct;
ltct = ltc;
if (bitcount < 64) {
bitval = (int) (ltct.data >> bitcount) & 0x01;
} else {
bitval = (int) (ltct.sync >> (bitcount - 64)) & 0x01; //backward
}
if ( (bitval == 1) || ( (bitval == 0) && (clkCnt & 0x01) ) == 0) {
state = !state; // toggle state
digitalWriteFast(ltcPin, state);
}
}
//https://www.geeksforgeeks.org/program-to-find-parity/
inline
int getParity(uint64_t n)
{
int parity = 0;
while
{
parity = !parity;
n = n & (n - 1);
}
return parity & 0x01;
}
/*
Gets called by rising edge of syncPin
*/
void startLtc() {
ltcTimer.begin(genLtc, ltcTimer_freq);
ltcTimer.priority(0);
int t, t10;
uint64_t data = ltc.data;
clkCnt = 0;
//get frame number:
t = ((data >> 8) & 0x03) * 10 + (data & 0x0f);
//zero out ltc data, leave d+c flags and user-bits untouched:
data &= 0xf0f0f0f0f0f0fcf0ULL;
//data = 0;
//inc frame-number:
//TODO: realize "drop frame numbering" (when D-Flag is set)
t++;
if (t >= (int) fps) t = 0;
//set frame number:
t10 = t / 10;
data |= (t10 & 0x03) << 8;
data |= ((t - t10 * 10)) << 0;
printTCout();
Serial.printf("%02d\n", t);
//set time:
t = second();
t10 = t / 10;
data |= (t10 & 0x07) << 24; //Seconds tens
data |= ((t - t10 * 10) & 0x0f) << 16;
t = minute();
t10 = t / 10;
data |= (uint64_t)(t10 & 0x07) << 40; //minute tens
data |= (uint64_t)((t - t10 * 10) & 0x0f) << 32;
t = hour();
t10 = t / 10;
data |= (uint64_t)(t10 & 0x03) << 56; //hour tens
data |= (uint64_t)((t - t10 * 10) & 0x0f) << 48;
//set parity:
int parity = (!getParity(data)) & 0x01;
if ((int) fps == 25) {
data |= (uint64_t) parity << 59;
} else {
data |= (uint64_t) parity << 27;
}
ltc.data = data;
}
void initLtcData()
{
ltc.sync = 0xBFFC;
ltc.data = (uint64_t) 0; //<- place your initial data here
}
void genFpsSync() {
static int state = 0;
state = !state; // toggle state
digitalWriteFast(syncPin, state);
}
void setup() {
Serial.begin(115200);
delay(200);
#ifdef USE_LTC_INPUT
AudioMemory(4);
#endif
setSyncProvider(getTeensy3Time);
pinMode(syncPin, OUTPUT);
pinMode(ltcPin, OUTPUT);
pinMode(2, INPUT_PULLUP);
ltcTimer_freq = (1.0f / (2 * 80 * (fps ))) * 1000000.0f - 0.125f;// -0.125: make it a tiny bit faster than needed to allow syncing
initLtcData();
//set frame number to last frame to force roll-over with new second()
ltc.data &= 0xf0f0f0f0f0f0fcf0ULL; //delete all dynamic data in frame
int t, t10;
t = fps;
t10 = t / 10;
ltc.data |= (t10 & 0x03) << 8;
ltc.data |= ((t - t10 * 10));
//now wait for seconds-change
int secs = second();
while (secs == second()) {;}
//start timer and pin-interrupt:
fpsTimer.begin(&genFpsSync, (1.0f / (2 * fps)) * 1000000.0f);
fpsTimer.priority(0);
attachInterrupt(digitalPinToInterrupt(syncPin), &startLtc, RISING);
NVIC_SET_PRIORITY(88, 0); //set GPIO-INT-Priority for Pin 1
}
void loop() {
if (ltc1.available()) {
ltcframe_t ltcframe = ltc1.read();
incominghours=ltc1.hour(<cframe);
incomingminutes=ltc1.minute(<cframe);
incomingseconds=ltc1.second(<cframe);
incomingframes=ltc1.frame(<cframe);
Serial.printf("TC in : %02d:%02d:%02d.%02d\n\n", ltc1.hour(<cframe), ltc1.minute(<cframe), ltc1.second(<cframe), ltc1.frame(<cframe));
}
bool inpin = digitalRead(2);
if (inpin==0 && insync==0){
if (incomingframes==0){
detachInterrupt(digitalPinToInterrupt(syncPin));
fpsTimer.end();
setTime(incominghours,incomingminutes,incomingseconds, 01, 01, 2022);
Teensy3Clock.set(now());
ltcTimer_freq = (1.0f / (2 * 80 * (fps ))) * 1000000.0f - 0.125f;// -0.125: make it a tiny bit faster than needed to allow syncing
initLtcData();
//set frame number to last frame to force roll-over with new second()
ltc.data &= 0xf0f0f0f0f0f0fcf0ULL; //delete all dynamic data in frame
int t, t10;
t = fps;
t10 = t / 10;
ltc.data |= (t10 & 0x03) << 8;
ltc.data |= ((t - t10 * 10));
//now wait for seconds-change
int secs = second();
while (secs == second()) {;}
//start timer and pin-interrupt:
fpsTimer.begin(&genFpsSync, (1.0f / (2 * fps)) * 1000000.0f);
fpsTimer.priority(0);
attachInterrupt(digitalPinToInterrupt(syncPin), &startLtc, RISING);
NVIC_SET_PRIORITY(88, 0); //set GPIO-INT-Priority for Pin 1
insync=1;
}
}
}
void printTCout(){
Serial.printf("TCout : %02d:%02d:%02d:", hour(), minute(), second());
}
