123mike456lev:
OK, I see how mentioning the 30 fps video without any explanation makes things confusing.I'm doing neuroscience research and I'm trying to sync two different recordings that are captured by separate computers. One of the recordings is essentially a 30 fps video of a rodent's behavior and the other is a recording of neural activity. The software that does the behavior recording is configured to send a string through a COM port at each frame of the video (i.e. 'u1' then 'd1' alternating on each frame), which I want to send to an Arduino. Then I want the Arduino to transmit alternating high/low TTL signals (based on the strings it's receiving) to the processor on the rig for the brain recording (which has a sampling rate of up to about 50 kHz, according to its product description) and for the TTL signals to be interpreted by the software that does the brain recording. The goal is to time-lock the recordings and make sure that the occasional dropped frame on the video recording doesn't de-sync the two recordings.
Let me see if I understand this a bit better. The "video" is just noise to your project and we don't care to know more.
What we now need explained is what is the "string" that is sent through a COM port. There must be more to the "string" than just "u1" then "d1". Does it ALWAYS send just two characters? If so, we only care that we receive 2 characters, any two characters.
But what are alternating high/low TTL signals based on the strings? Do we somehow tie the "u1" and d1 to the digital write of a 1 or a 0 to a pin. If true, how accurate does the timing need to be?
Paul