Blackmagic Micro Studio Camera 4K G2 - Page 682

The example sketch above shows how the Blackmagic 3G-SDI Shield for Arduino is programmed
to detect a tally signal for input 1 or 2 via the switcher’s tally output, and then embed that tally signal
into the shield’s SDI output. The tally light on the corresponding camera will then illuminate.
682Connecting Tally using the Blackmagic3G-SDI Shield for Arduino