SPPLE demo, reading RSSI when low energy connection is established

Mateusz Maciag

Hi,

I have a problem with reading RSSI when LE connection is established. I use SPPLE demo example for a client and SPPLE demo lite for a server. I would like to measure RSSI on client side so I have written simple periodic task called every 1 second:

void ProcessRSSI()
{
	int RSSI;
	int ret_val;
	Byte_t Status;
	Word_t ConnRes;

	if(RSSI_Context.TrackRSSI_Enabled)
	{
		ret_val = VS_Read_RSSI(BluetoothStackID, RSSI_Context.ConnectionID, &RSSI);
		Display(("RSSI: %d (ConnId = %d, HCI retval = %d)\r\n", RSSI, RSSI_Context.ConnectionID, ret_val));

		ret_val = HCI_Read_RSSI(BluetoothStackID, RSSI_Context.ConnectionID, &Status, &ConnRes, &RSSI);
		Display(("RSSI: %d (ConnId = %d, HCI retval = %d, status = %d)\r\n", RSSI, ConnRes, ret_val, Status));
	}
}

ConnectionID is taken from command line:

if((LEConnectionIndex = FindLEIndexByAddress(BD_ADDR)) >= 0) {
				Display(("Tracking RSSI enabled."));
				RSSI_Context.TrackRSSI_Enabled = TRUE;
				RSSI_Context.RSSI = -127;
				RSSI_Context.ConnectionID = LEContextInfo[LEConnectionIndex].ConnectionID;
			}

VS_Read_RSSI was added by me in BTVS.c. This is based on similar implementation I have found here in e2e:

int BTPSAPI VS_Read_RSSI(unsigned int BluetoothStackID, Byte_t ConnectionHandle, int* RSSI)
{
	int ret_val;
	Byte_t Length;
	Byte_t Status;
	Byte_t ConnHandle[2];
	Byte_t Buffer[32];
	Byte_t OGF;
	Word_t OCF;

	ConnHandle[0] = ConnectionHandle & 0xFF;
	ConnHandle[1] = (ConnectionHandle >> 8) & 0xFF;
	Length = sizeof(Buffer);
	OGF = VS_COMMAND_OGF(VS_READ_RSSI_COMMAND_OPCODE);
	OCF = VS_COMMAND_OCF(VS_READ_RSSI_COMMAND_OPCODE);
	ret_val = HCI_Send_Raw_Command(BluetoothStackID, OGF, OCF, sizeof(ConnHandle), (Byte_t *)&ConnHandle, &Status, &Length, Buffer, TRUE);

	*RSSI = (int)((signed char)Buffer[3]);
	ret_val = MapSendRawResults(ret_val, Status, Length, Buffer);

	return ret_val;
}

When I create LE connection (commands: client, connectle <bd_addr>, discoverspple <bd_addr>) i get ConnectionID equal to 1. Unfortunately reading RSSI gives error 0x02 (No connection?). After that I have created SPP connection (open <inquiry index> <port>) and tried to read RSSI again (ConnectionID was still equal to 1) and I got:

RSSI: -69 (ConnId = 1, HCI retval = 0)
RSSI: -256 (ConnId = 1, HCI retval = 0, status = 0)

It seems to work now. So is the connection ID handled differently in BLE ? How to use this vendor specific command when only LE connection is active.

Regards,

Matthew

over 9 years ago

0 Sundeep Javvaji over 9 years ago

TI__Mastermind 32615 points

Hi,

When it comes to the command execution, it is the same.

0 Mateusz Maciag over 9 years ago in reply to Sundeep Javvaji

Prodigy 120 points

HI,

Thanks for response. So VS_Read_RSSI should just work for LE connections?

SPP+LE>connectle 00183342A282
Connection Request successful.

SPP+LE>
etLE_Connection_Complete with size 18.
   Status:       0x00.
   Role:         Master.
   Address Type: Public.
   BD_ADDR:      0x00183342A282.

SPP+LE>
etGATT_Connection_Device_Connection with size 12:
   Connection ID:   1.
   Connection Type: LE.
   Remote Device:   0x00183342A282.
   Connection MTU:  23.

SPP+LE>
Exchange MTU Response.
Connection ID:   1.
Transaction ID:  1.
Connection Type: LE.
BD_ADDR:         0x00183342A282.
MTU:             50.

For lines above I would expect status = 0. Unfortunately I get error -2 which means "no connection":

RSSI: 0 (ConnId = 1, HCI retval = 0, status = 2)
RSSI: 0 (ConnId = 1, HCI retval = -502)

I should have added that I use CC256x based module (patch version 2.1) and latest Bluetopia stack. Any idea would be helpful.

0 Sundeep Javvaji over 9 years ago in reply to Mateusz Maciag

TI__Mastermind 32615 points

Hi,

That is strange.

Can you try the stranded Send_HCI_Read_RSSI (0x1405) command from the spec

OCF --> 0x0005
OGF --> 0x05

and see it it works

0 Mateusz Maciag over 9 years ago in reply to Sundeep Javvaji

Prodigy 120 points

Hi,

Send_HCI_Read_RSSI did not help. But I have found that GAP_LE_Query_Connection_Handle returns ID = 1025. I used this value as a parameter for both VS_Read_RSSI and HCI_Read_RSSI but I am still getting error no. 2.

0 Stonestreet One Support over 9 years ago in reply to Mateusz Maciag

Mastermind 7225 points

Hi,

Could you check the return you are getting for GAP_LE_Query_Connection_Handle? It looks the 1025 is the return for the Connection Handle Result and not the actual Connection Handle itself that needs to be used for HCI_Read_RSSI.

Thanks,

Stonestreet One.

0 Mateusz Maciag over 9 years ago in reply to Stonestreet One Support

Prodigy 120 points

Hi,

after long break I have returned to this problem and, well, solved it. Not sure what I have messed up in SSPLEDemo but in my project HCI_Read_RSSI combined with GAP_LE_Query_Connection_Handle works very well. I do not want to leave this thread unanswered so here is some portion of code:

int16_t GetRSSI (int8_t *rssi)
{
	Word_t ConnectionHandle, RetConnectionHandle;
	Byte_t StatusResult;

	int Result;

	Result = GAP_LE_Query_Connection_Handle(BluetoothStackID, RemoteBD_ADDR, &ConnectionHandle);
	if(Result < 0) {
		return ERROR;
	}

	Result = HCI_Read_RSSI(BluetoothStackID, ConnectionHandle, &StatusResult, &RetConnectionHandle, (SByte_t*) rssi);
	if(Result < 0) {
		return ERROR;
	}

	if(StatusResult != HCI_ERROR_CODE_NO_ERROR) {
		return ERROR;
	}

	return OK;
}

Best regards,
Matthew

Bluetooth®︎

Bluetooth forum

SPPLE demo, reading RSSI when low energy connection is established