Not sure if a conflict may happen, but if you want to be sure, why not set a flag to warn the timer that user is sending data? This way, the timer, may proceed when this flag is set to false (sending data is finished). Same way, when timer is searching for data, put a flag to delay a bit the sent data from user. Anyway, before such attempt, I would go for testing sending and receiving by creating a loop to see the results.