CCS/CC2640R2F: Read Characteristic Value from a Device (Thermometer)

Fares Rabuts

Part Number: CC2640R2F

Tool/software: Code Composer Studio

Hello,

I try to read the Characteristic Value from a Thermometer. I use the CC2640RF as a central, i make a BLE connection with the Thermometer and i wold like to read the "Temperature Measurement Characteristic".

How can I read the value?

// Temperature Measurement Characteristic defines
#define HT_TEMPERATURE_MEASUREMENT_ID 0
#define HT_TEMPERATURE_MEASUREMENT_UUID 0x2A1C
#define HT_TEMPERATURE_MEASUREMENT_LEN 20
#define HT_TEMPERATURE_MEASUREMENT_LEN_MIN

I use this code:

// Do a read
uint8_t status;
attReadReq_t req;

req.handle = (uint16)HT_TEMPERATURE_MEASUREMENT_UUID;
status = GATT_ReadCharValue(connHandle, &req, selfEntity);

if (status == SUCCESS)
{
Display_print0(dispHandle, 9, 0, "SUCCESS");
}

best reagrds,

Fares Rabuts

over 7 years ago

0 Christin Lee over 7 years ago

TI__Guru 56395 points

You need to do a general service discovery first. Is your thermometer also TI device?

0 Fares Rabuts over 7 years ago in reply to Christin Lee

Intellectual 495 points

Hello Christin,

No, it es from Philips (Ear thermometer). I have now a new Problem, my GATT_ReadCharValue() returned SUCCESS, but at :

else if ((pMsg->method == ATT_READ_RSP) ||
((pMsg->method == ATT_ERROR_RSP) &&
(pMsg->msg.errorRsp.reqOpcode == ATT_READ_REQ)))
{
if (pMsg->method == ATT_ERROR_RSP)
{
Display_print1(dispHandle, 4, 0, "Read Error %d", pMsg->msg.errorRsp.errCode);
}
else
{
// After a successful read, display the read value
Display_print1(dispHandle, 4, 0, "Read rsp: %d", pMsg->msg.readRsp.pValue[0]);
}

i got ATT_ERROR_RSP.
I think that i must to enable the Indication or the Notification, How i can do that?
I use the this function GATT_Indication(), but the CC2640R2F stands still.

attHandleValueInd_t *pInd;
pInd->handle = charHdl;
pInd->len = (uint16)HT_TEMPERATURE_MEASUREMENT_LEN;
pInd->pValue = (uint8 *)ATT_MTU_SIZE;
//GATT_Notification(connHandle, pNoti, authenticated);
status = GATT_Indication(connHandle, pInd, 0x02, selfEntity);

Sorry about my Englisch

best regards,
Fares Rabuts

0 Christin Lee over 7 years ago in reply to Fares Rabuts

TI__Guru 56395 points

Have you checked if you get a valid handle for service discovery? Can you provide sniffer log?

The GATT_ReadCharValue only checks if it's a valid handle value, client is available to operate a att read, but it does not know if this is the correct handle for a read type characteristic.

What you can try is to program CC2640R2 as host test and using Btool to do a full service discovery. Then you can write down the handle of interest.

You can then start implementing simple_central and can verify the handle based on the BTool overview.

You can take a look at the following sessions in SimpleLink Academy:
dev.ti.com/.../ble_01_basic.html

dev.ti.com/.../ble_01_custom_profile.html

0 Fares Rabuts over 7 years ago in reply to Christin Lee

Intellectual 495 points

Hello Christin,

the Characteristic wich i try to read is an indicated Characteristic, and i think, i should to enable the indication. i read that i should write the the Value {0x01,0x00} to the Characteristic Descriptor. How can i do that ?

I do this:

attReadByTypeReq_t req;

// Discover characteristic

discState = BLE_DISC_STATE_CHAR;

req.startHandle = svcStartHdl;

req.endHandle = svcEndHdl;

req.type.len = ATT_BT_UUID_SIZE;

req.type.uuid[0] = LO_UINT16(HT_TEMPERATURE_MEASUREMENT_UUID);

req.type.uuid[1] = HI_UINT16(HT_TEMPERATURE_MEASUREMENT_UUID);

bStatus_t status = GATT_DiscCharsByUUID(connHandle,&req,selfEntity);

if(status == SUCCESS){

Display_print0(dispHandle, 8, 0, "GATT_DiscCharsByUUID: Success" );

}

// Characteristic found, store handle

if ((pMsg->method == ATT_READ_BY_TYPE_RSP) &&

(pMsg->msg.readByTypeRsp.numPairs > 0))

{

charHdl = BUILD_UINT16(pMsg->msg.readByTypeRsp.pDataList[0],

pMsg->msg.readByTypeRsp.pDataList[1]);

attWriteReq_t pReq;

pReq.handle = charHdl;

pReq.len = 1;

uint8 onPacket [] = {0x01,0x00};

pReq.pValue = onPacket;

pReq.sig = 0;

pReq.cmd = 0;

bStatus_t status = GATT_WriteCharDesc(connHandle,&pReq,selfEntity);

if ( status == SUCCESS )

{

Display_print0(dispHandle, 9, 0, "GATT_WriteCharDesc: Success" );

}else{

Display_print0(dispHandle, 9, 0, "GATT_WriteCharDesc: NOT SUCCESS" );

}

I get :

GATT_DiscCharsByUUID: Success

GATT_WriteCharDesc: NOT SUCCESS

How to insert the Handle ?

best regards,

Fares

0 Christin Lee over 7 years ago in reply to Fares Rabuts

TI__Guru 56395 points

Unfortunately the newer SDKs do not contain example code for using indication.
However, in our BLE STACK 2.2.2, there does exist example using indication. You can take a look at the glucose_collector example.
You can download BLE STACK 2.2.2 here:
www.ti.com/.../BLE-STACK

Code Composer Studio™︎

Code Composer Studio forum

CCS/CC2640R2F: Read Characteristic Value from a Device (Thermometer)