I am developing an android app for handling BLE devices. I need to connect two BLE device at the same time and read/write characteristics,services from/to the device at the same time. How can I do this? Is it needed separate GATT instance and callback for each device? How to do this?
It's very simple. Just execute connectGatt one time for every device, which will then give you one BluetoothGatt object per device. The callback object can be the same, or a separate instance per device, it's up to you, although I guess it's easier if you have one instance per device.