[TW#14140] Simple Bluetooth Example

[alexgrauer]

Hi all,

I open this thread because im having problems to make BLE work. Im using the gatt_server_service_table example, but im not being able to change the read value of Heart Rate Control Point.

Im doing the following:

In the gatts_profile_event_handler i added: case ESP_GATTS_READ_EVT: heart_ctrl_point[1] += 0x01; ESP_LOGI(GATTS_TABLE_TAG, "READ EVENT: %d\n",heart_ctrl_point[1]); break;

When i read the value using the nRF Connect App i can see the READ EVENT text in the monitor, and the heart_ctrl_point is actually being incremented. But in the App i still see 0x00 every time i read it.

Any clue?

Thanks in advance, Alex

[mh-dev]

This depends on if you're using auto response or not. There is an api to set attribute values which is what you should use it is esp_ble_gatts_set_attr_value. Setting it in the read event does probably not what you want. Since I expect the value is already defined at this point. Another thing is that esp_ble_gatts_set_attr_value is an async operation.

[FayeY]

Hi @alexgrauer , did the above suggestion help you resolve the issue?

[alexgrauer]

Hi @FayeY, I wasnt able to solve it yet. Im not sure if im calling the esp_ble_gatts_set_attr_value correctly. Im not sure i understand the parameters that go with it.

@mh-dev, if i set it in the read event, should i read the new value the next time i read it?

[mh-dev]

You should checkout https://github.com/espressif/esp-idf/blob/master/examples/bluetooth/gatt_server/main/gatts_demo.c#L271-L281

[Weijian-Espressif]

@alexgrauer , you shoud do like this :

case ESP_GATTS_READ_EVT: heart_ctrl_point[0] += 0x01; esp_ble_gatts_set_attr_value(param->read.handle, sizeof(heart_ctrl_point), heart_ctrl_point); ESP_LOGI(GATTS_TABLE_TAG, "READ EVENT: %d\n",heart_ctrl_point[0]); break;

The attachment is the test demo gatts_table_creat_demo.c.zip

[alexgrauer]

Thanks very much @Weijian-Espressif, that worked!! Now, if i want to change heart_ctrl_point´s value from another function, not from the READ_EVT, what should i put instead of param->read.handle.

And also, is it possible to make heart_ctrl_point uint32 instead of uint8?

Thanks again

[Weijian-Espressif]

@alexgrauer maybe you can refer to gatts_demo.c , you can use ble app test, you can write some data to the demo, and after your app enable demo's notify, the demo would send you some data. gatts_demo.c.zip

[FayeY]

Hi @alexgrauer , did the above suggestion help you resolve the issue?