The maximum byte can received per package used Nordic UART Android app?

[Carey]

I changed the number of byte in one package from 20 to 250, but I used Nordic UART Android app to receive date, it also just can received 20 byte per package, is it passible to received 250byte per package used Nordic UART app in the Android mobile phone?

[Hung Bui]

Hi Carey,

It depends if your Android support long MTU or not. Usually on Android it's 23 bytes MTU (3 byte for ATT header so you have 20 bytes for payload). Our max supported ATT MTU is 512 bytes. On iOS it's 158 bytes.

However, even if it's only 23 byte ATT MTU, it's still possible to send 250 byte using a read request instead of notification. So rather than the slave sending notification, you can use the master to read the value of a characteristic.

If you do need notification, what you need to do is to manually split your data into 20 byte chunks and then send them one after another.