Android Ble Write 'oncharacteristicwrite' Returns Status Gatt_write_not_permitted

I've been trying to create a small Android BLE app that sends some bytes of data to a BLE device (an HM-10 module). Using existing applications on the Play Store I've been able to

Solution 1:

It means that the remote device doesn't permit you to write to that characteristic (although it has set the writable bit in the properties...)

But you shouldn't loop through the services like that and just write to the first writable characteristic you find. Instead find the correct service and characteristic by uuid to make sure you find the correct one.