> I lay in bed, sleepless as usual, watching the smoke alarm blink. It blinked and blinked and I realized I had no idea what that meant. Whereas this new devic

> I lay in bed, sleepless as usual, watching the smoke alarm blink. It blinked and blinked and I realized I had no idea what that meant. Whereas this new device glows green, or sometimes yellow. Or other colours. What does that mean? I'll have to check the manual anyway, or wait for the 'human voice' to explain. The beauty of smoke detectors is that they are a minimal set of electronics required to perform the task. This minimises chances of failure, since the circuitry is sufficiently simple that it can be understood. Perhaps it can even be formally proven? Not sure if that has been done for any end-user device. Once you start building an ARM computer, OS, wifi, SMS etc into such a device the complexity and failure conditions balloon. Edit: this device _might_ have an isolated, decoupled sensor unit but it still has to interact with the more complex upper-level functions in order to signal an alarm.