Using WriteRXCharacteristics in Bluetooth to send integer data to micro:bit

Hi all,

I am quite new to bluetooth uart transfer between phone and micro:bit using App inventor. I have tried to use WriteRXCharacteristics to send messages from phone to micro:bit. It has been successful to transmit text data (e.g. WriteRXCharacteristics ("Start.") in AI while on the micro:bit side reading the text data until "."). However if I replace it with WriteRXCharacteristics ("5.") while for the same on the micro:bit side, the 5 cannot be read and display on the micro:bit.

May I know how to solve this problem. Thanks.