Time-triggered event handlers must run quickly, finishing well before the next time period occurs. To ensure this, keep your timer handlers concise. There is no guarantee that a timing handler will run precisely on schedule. If a SNAPpy function is running when the time hook would otherwise occur, the running code will not be interrupted to run the timer hook code. Whiteboard Videos are a great way to engage your customers and generate new revenue website to increase user engagement. Defining your own ISR isn't an option, unfortunately. If you're going to read this device via a GPIO pin, then polling for the start bit is really your only option, and you'll have to live with the consequences of blocking the event loop for extended periods of time - poor wireless performance (not that wireless is 100% reliable even at the best of times), and inaccurate timing (your next HOOK_1S routine invocation will be well over 1 second away).