The issue involves poor Bluetooth LE connect-ability when the iPhone SE (iOS 13.5.1) has
screen-off. There is no issue on the iPhone SE only when the screen is
on, whether the App is in the foreground or background. There is no issue
with an iPhone 8 (same iOS version), whether screen-off or screen-on.
This issue and behavior shows consistent on all iPhones tested, which is at
least 5 different iPhone SE units and >20 iPhone 8 units.
Poor connect-ability can be
described as being unable (or rarely able) for iPhone to connect to the
existing paired Bluetooth peripheral device that is running custom iOS App
(that otherwise runs fine on iPhone 8). We are used to connect-ability
within 3 minutes. Only with iPhone SE screen off, it would go at least
several hours before connecting once, and often would go days indefinitely
(tested several days) without connection unless screen was awakened to be on
(then within minutes, it connects).
The peripheral device advertises
a 12-second burst of advertisements every 3-minutes indefinitely. The
central and its App is meant to connect once per 3-minutes, exchange payload
(typically < 10s), then disconnect, and scan again for the next
advertisements 3-minutes later. The advertising interval is 152.5ms, as
per Apple Accessory Design Guidelines.
We are investigating with
Bluetooth LE packet sniffers, and can put together some log files if/when
needed.
screen-off. There is no issue on the iPhone SE only when the screen is
on, whether the App is in the foreground or background. There is no issue
with an iPhone 8 (same iOS version), whether screen-off or screen-on.
This issue and behavior shows consistent on all iPhones tested, which is at
least 5 different iPhone SE units and >20 iPhone 8 units.
Poor connect-ability can be
described as being unable (or rarely able) for iPhone to connect to the
existing paired Bluetooth peripheral device that is running custom iOS App
(that otherwise runs fine on iPhone 8). We are used to connect-ability
within 3 minutes. Only with iPhone SE screen off, it would go at least
several hours before connecting once, and often would go days indefinitely
(tested several days) without connection unless screen was awakened to be on
(then within minutes, it connects).
The peripheral device advertises
a 12-second burst of advertisements every 3-minutes indefinitely. The
central and its App is meant to connect once per 3-minutes, exchange payload
(typically < 10s), then disconnect, and scan again for the next
advertisements 3-minutes later. The advertising interval is 152.5ms, as
per Apple Accessory Design Guidelines.
We are investigating with
Bluetooth LE packet sniffers, and can put together some log files if/when
needed.