WL1835MOD: Failed to read value from Bluetooth LE device

Part Number:WL1835MOD

Using a HW based on AM335X and WL1835MOD. Operating system is linux.

Bluetopia is  BluetopiaPM-4.2.1.0.1.

External device is a ambient sensor.

I can scan and connect the sensor. But any read of characteristic failed and returns  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

The combination sensor and a PC or iphone is working.

I use the following steps:

root@am335x-evm:/home/testApp# ./SS1BTPM &
root@am335x-evm:/home/testApp# ./LinuxGATM_CLT

    Initialize 1
    
    SetDevicePower 1
    
    StartDeviceDiscovery 1 20
    
    QueryRemoteDeviceList 10
    
    QueryRemoteDeviceProperties 0CF3EEAADCFD 1
    
    RegisterGATTCallback
    
    RegisterAuthentication
    
    EnableBluetoothDebug 1 1 bt.log
    
    ConnectWithRemoteDevice 0CF3EEAADCFD 1
    
    QueryRemoteDeviceServices 0CF3EEAADCFD 1 1 0
    
    QueryRemoteDeviceServices 0CF3EEAADCFD 1 0 520
    
    ReadValue 0CF3EEAADCFD 0x0012 0 1

GATM>ReadValue 0CF3EEAADCFD 0x0012 0 1

GATM_ReadValue() Success: Transaction ID = 1.
GATM>
GATT Read Response Data
    Connection Type:  LE
    Remote Address:   0CF3EEAADCFD
    Transaction ID:   1
    Attribute Handle: 0x0012 (18)
    Final?:           YES
    Value Length:     20
    Value:            
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

We run WireShark and saw differences while execution of the ReadValue command. If run from iphone the BLE seems to be used. If run from AM335x the BLE ATT seems to be used.

WireShark dumps are available.