Solution: Sync Flash to GS Camera with use of the XVS PIN and an Pico or Arduino #4034
Description
I was working on that for 2 days and finally found a perfect solution that is not in the docs. I don't know how to make a Pull Request correctly, but maybe someone else will use my information.
I Used a BC547 transistor
XVS--1k--BASE
PicoPIN--1k--COLLECTOR
GND--EMITTER
GND has to be connected between Pico and Camera.
I am collecting the picture with an C++ Code in StillCapure Mode and fixed FrameDurationTime to 1ms. If you change this, you should change the FLASH_TIMER_DURATION too. This could also be done with serial commands directly to the Pico to match the values (not in the code).
I am always starting and stopping the camera in the code, because I don't want to flash all the time.
cam_device->start();
wait till captured...
cam_device->stop();
The XVS Pin triggers twice for every pic.
HIGH - 20us - LOW - 32384us - (takes picture for FrameDurationTime (e.g. 1000us)) - HIGH - 20us - LOW
The picture is taken before(!!!) the second HIGH signal.
So the timing is important!
I am triggering the flash 32384us after the first HIGH signal.
Arduino Code:
#define TriggerPIN 3 //D03 (Uno, Nano, Mini) #define StatusLED 13 //D13 // to find the perfect timing window set FLASH_TIMER_DURATION=2 and then change the FLASH_TIMER_DELAY up and down to find the limits (point the camera on the Status LED and watch the brightness change) // 502 off // 503 weak // 504 better // 505 full // . // . // . // 518 full // 519 better // 520 weak // 521 off ` #define FLASH_TIMER_DELAY 505 // (16 MHz / 1024) * 0.032384 - 1 ≈ 505 für 32,384ms Interrupt #define FLASH_TIMER_DURATION 15 // (16 MHz / 1024) * 0.001024 - 1 ≈ 15 für 1,024ms Interrupt unsigned long starttime, endtime, duration, pause; unsigned int triggered=0, status=0, i=0, FLASH_ON=0; void setup() { pinMode(StatusLED,OUTPUT); // set PIN to OUTPUT digitalWrite(StatusLED,LOW); // set PIN to LOW (StatusLED OFF) pinMode(TriggerPIN,INPUT_PULLUP); // set PIN to INPUT attachInterrupt(digitalPinToInterrupt(TriggerPIN),TriggerISR,CHANGE); // SET InterruptPIN, ISR and Mode // Timer TCCR1A = 0; TCCR1B = (1 << WGM12) | (1 << CS12) | (1 << CS10); // CTC Modus, Prescaler 1024 OCR1A = FLASH_TIMER_DELAY; TIMSK1 = (1 << OCIE1A); // Timer1 Compare Match Interrupt aktivieren interrupts(); // enable Interrupts Serial.begin(115200); // initialize serial } void loop() { if (triggered==0) { TCNT1 = 0; // Timer reset } if (status==1) { status=0; Serial.println(i); Serial.print("pause:"); Serial.print(pause/1000); Serial.println("ms"); Serial.print("duration:"); Serial.print(duration); Serial.println("us"); Serial.println("-------------------------"); i++; } } void TriggerISR() { // ISR function excutes when PIN is triggered if (digitalRead(TriggerPIN)==HIGH) { // check if PIN is high or low and set Flash PIN if (triggered==0) { triggered=1; TCNT1 = 0; // Timer reset } starttime = micros(); pause=(starttime-endtime); } else { endtime = micros(); duration=endtime-starttime; status=1; // allow posting new Timings } } ISR(TIMER1_COMPA_vect) { // Timer if (FLASH_ON==0) { digitalWrite(StatusLED,HIGH); TCNT1 = FLASH_TIMER_DELAY - FLASH_TIMER_DURATION; // Timer reset to 1ms FLASH_ON=1; } else { digitalWrite(StatusLED,LOW); FLASH_ON=0; triggered=0; } }