SO2R Lockout

This repository maintains a simple Push-To-Talk (PTT) lockout interface for Single-Operator, Two-Radio (SO2R) amateur radio operation to ensure only one radio is transmitting at any given time.

Overview

This interface will arbitrate two PTT channels on a first-come, first-serve basis or priority basis.

Usage

Each PTT channel has an input for a physical interface such as a footswitch and an opto-isolated output to enable the radio's transmitter.

First-Come, First-Serve Mode

By default, the lockout acts on a first-come, first serve basis meaning the first channel to trigger its PTT input will enable transmit and hold the lock until that channel's PTT input is released. Once the lock is released, if the other channel is requesting transmit with its PTT input, the other channel will immediately claim the lock and the other radio's transmit will be enabled. Arbitration resets when both PTT inputs are released.

Priority Mode

Priority mode may be selected by holding a single channel's PTT trigger at power-on. The channel selected at power-on is given priority over the other channel until power is cycled. In priority mode, the priority channel will always take the lock from the lower-priority channel and immediately disable transmit on the lower-priority channel. When selecting priority mode at startup, neither radio's transmit will be enabled until both PTT inputs have been released. If both PTT channels are triggered at power-on, the interface will remain in first-come, first-serve mode.