Thanks for reaching out to us and sorry about the lack of the knock function on Android devices!
Unfortunately, at this point the knock function is only available for iOS devices. Because Android devices do not have standardized hardware and operating systems, we're not able to support the knock function across all the thousands of Android devices that are available on the market. Device fragmentation is a huge issue for this feature since different OSes and manufacturers treat the knock input differently, which means that not only is knock not possible for many devices, but also it would take us significant development and testing to bring knock to those devices that can support this feature. Since it would take a lot of time and resources for us to implement a feature that would benefit only a small subset of Android devices, we've decided to focus our Android development efforts on implementing additional new features that will benefit all of our Android users instead.
We did not foresee this problem when we announced the features we would be bringing to Sesame, and we apologize for failing to live up to our claims. Even though we can't bring the knock function to Android, it's important to us to continue to bring new features to our Sesame Android app that make our users' lives easier, so please let us know if you have any further feedback or feature requests for us! - CANDY HOUSE