The Blackmagic GPI and Tally Interface is a professional GPIO bridge designed to bring industry‑standard tally indicators and automation triggers to ATEM production switchers and broadcast workflows. It converts general purpose input and output signals into switcher‑compatible tally states, allowing external devices such as lighting controllers, studio tally lamps, automation systems and custom hardware panels to respond instantly to program and preview changes. The interface provides multiple contact‑closure inputs that can trigger macros or switcher events, while simultaneously offering tally outputs for routing on‑air indications to cameras, talent lights or control room displays. Engineered for reliable 24/7 operation inside broadcast racks, the unit ensures clean electronic isolation between the switcher and connected equipment, maintaining stable signaling even in complex studio environments. Its compact design integrates seamlessly into ATEM‑based productions, enabling precise, hardware‑level synchronization between live switching actions and the wider studio control ecosystem.