How to handle characteristic data?

[Andreas]

Hello,

For me, at the moment there are two things unclear. With the help of some Nordic examples, I was able to add a Service with 3 characteristics to the used S120 BLE stack. I`m able to connect to the PCA10028 demoboard via a Smartphone. I can see the service/characteristics with the nordic master control panel (Android).

The first two characteristics are defined readable only. The 3rd characteristic is defined readable/writable.

So the first question is, how I can add data to the first two characteristics? For example, I want to write 0xFFAAFFAA to the first chracteristic. My expectation is, if I read out the first characteristic with the Smartphone, I get 0xFFAAFFAA. Where do I have to place this data to the characteristic?

The second question is, how do I get data written from the Smartphone? I tried to see the written data (for example 0xFF) with the debugger (watch window). But I wasn`t able to get the written data. In which function do I have to handle the received data? In which variable the received data is stored?

Thanks in advance for any help!

Regards!

[Andreas]

Hello Ulrich,

thanks for your answer and sorry for my misunderstanding. Currently I`m not able to get this topic running. :-( Here is how I add my "sernum" characteristic.

static uint32_t sernum_char_add(ble_device_t * p_dev, const ble_device_init_t * p_dev_init)
{
    ble_gatts_char_md_t char_md;
    ble_gatts_attr_md_t cccd_md;
    ble_gatts_attr_t    attr_char_value;
    ble_uuid_t          ble_uuid;
    ble_gatts_attr_md_t attr_md;
		int i=0;
	
		for(i=0;i<4;i++)
		{
			sernum[i]= i;
		}

    memset(&cccd_md, 0, sizeof(cccd_md));

    BLE_GAP_CONN_SEC_MODE_SET_OPEN(&cccd_md.read_perm);
    BLE_GAP_CONN_SEC_MODE_SET_OPEN(&cccd_md.write_perm);

    cccd_md.vloc = BLE_GATTS_VLOC_STACK;

    memset(&char_md, 0, sizeof(char_md));

    char_md.char_props.notify = 1;
    char_md.p_char_user_desc  = NULL;
    char_md.p_char_pf         = NULL;
    char_md.p_user_desc_md    = NULL;
    char_md.p_cccd_md         = &cccd_md;
    char_md.p_sccd_md         = NULL;

    ble_uuid.type = p_dev->uuid_type;
    ble_uuid.uuid = BLE_UUID_DEV_SERNUM_CHARACTERISTIC;

    memset(&attr_md, 0, sizeof(attr_md));

    BLE_GAP_CONN_SEC_MODE_SET_OPEN(&attr_md.read_perm);
    BLE_GAP_CONN_SEC_MODE_SET_OPEN(&attr_md.write_perm);

    attr_md.vloc    = BLE_GATTS_VLOC_STACK;
    attr_md.rd_auth = 0;
    attr_md.wr_auth = 0;
    attr_md.vlen    = 1;

    memset(&attr_char_value, 0, sizeof(attr_char_value));

    attr_char_value.p_uuid    = &ble_uuid;
    attr_char_value.p_attr_md = &attr_md;
    attr_char_value.init_len  = (4*sizeof(uint8_t));
    attr_char_value.init_offs = 0;
    attr_char_value.max_len   = BLE_DEVICE_MAX_SERNUM_LEN;
		attr_char_value.p_value = sernum;

    return sd_ble_gatts_characteristic_add(p_dev->service_handle,
                                           &char_md,
                                           &attr_char_value,
                                           &p_dev->sernum_handles);

}

sernum is a global array variable. So for my understanding attr_char_value.p_value points to the content of the array (filled with 0, 1, 2, 3). But if I try to read this characteristic with the android Master Control Panel, I only get: "Value: Notifications enabled". Where is my mistake!

Regards!