NCS Zephyr HRS coded phy sample: Enabling notification on multiple characteristics.

[Sudhir]

The hrs.c has the following code.

/* Heart Rate Service Declaration */
BT_GATT_SERVICE_DEFINE(hrs_svc,
BT_GATT_PRIMARY_SERVICE(BT_UUID_HRS),
BT_GATT_CHARACTERISTIC(BT_UUID_HRS_MEASUREMENT, BT_GATT_CHRC_NOTIFY,
BT_GATT_PERM_NONE, NULL, NULL, NULL),
BT_GATT_CCC(hrmc_ccc_cfg_changed,
BT_GATT_PERM_READ | BT_GATT_PERM_WRITE),
BT_GATT_CHARACTERISTIC(BT_UUID_HRS_BODY_SENSOR, BT_GATT_CHRC_READ,
BT_GATT_PERM_READ, read_blsc, NULL, NULL),
BT_GATT_CHARACTERISTIC(BT_UUID_HRS_CONTROL_POINT, BT_GATT_CHRC_WRITE,
BT_GATT_PERM_NONE, NULL, NULL, NULL),
);

static void hrmc_ccc_cfg_changed(const struct bt_gatt_attr *attr, uint16_t value)
{
ARG_UNUSED(attr);

bool notif_enabled = (value == BT_GATT_CCC_NOTIFY);

LOG_INF("HRS notifications %s", notif_enabled ? "enabled" : "disabled");
}

I would like to change the BT_UUID_HRS_BODY_SENSOR to provide notifications. 

Should I do the following:

/* Heart Rate Service Declaration */
BT_GATT_SERVICE_DEFINE(hrs_svc,
BT_GATT_PRIMARY_SERVICE(BT_UUID_HRS),
BT_GATT_CHARACTERISTIC(BT_UUID_HRS_MEASUREMENT, BT_GATT_CHRC_NOTIFY,
BT_GATT_PERM_NONE, NULL, NULL, NULL),
BT_GATT_CCC(hrmc_ccc_cfg_changed,
BT_GATT_PERM_READ | BT_GATT_PERM_WRITE),
BT_GATT_CHARACTERISTIC(BT_UUID_HRS_BODY_SENSOR, BT_GATT_CHRC_NOTIFY,
BT_GATT_PERM_NONE, NULL, NULL, NULL),
BT_GATT_CCC(hrmc_ccc_cfg_changed,
BT_GATT_PERM_READ | BT_GATT_PERM_WRITE),
BT_GATT_CHARACTERISTIC(BT_UUID_HRS_CONTROL_POINT, BT_GATT_CHRC_WRITE,
BT_GATT_PERM_NONE, NULL, NULL, NULL),
);

Would that send notifications for both characteristics? If I have five characteristics, should I do that in a similar fashion?

[JONATHAN LL]

Hi and sorry for the slows response,

Have you testes\figured it out?


I have not tested this myself so i will have to get back to you within the week
Regards,
Jonathan

[JONATHAN LL]

Hi,
Changing the BT_GATT_CHARACTERISTIC() declaration only change the characteristic's property , meaning that the characteristic would support Notification but it doesn't do the actual notifying, the bt_hrs_notify() does the notifying.  You can also look at the peripheral_hr example there notify is also used for battery level notification every 1 sec. 

NOTE:  Usually Bluetooth SIG defined service/characteristic should not be changes to much as properties are defined by spec. 
Regards,
Jonathan