How to indicate of new characteristics to client without refreshing the nrf connect app in nrf ble?

RE: How to indicate of new characteristics to client without refreshing the nrf connect app in nrf ble?

haakonsh — Tue, 01 Aug 2023 11:54:13 GMT

I think setting end_handle to 0xFFFF is the issue. I doubt your attribute table has 65k entries. The API docs for sd_ble_gatts_service_changed states the context for BLE_ERROR_INVALID_ATTR_HANDLE:

"Invalid attribute handle(s) supplied, handles must be in the range populated by the application".

-Edit: Also, I think start_handle might need to be larger than zero, because that handle index is reserved.

RE: How to indicate of new characteristics to client without refreshing the nrf connect app in nrf ble?

Ayu7 — Thu, 27 Jul 2023 09:07:54 GMT

Hi, I am putting question properly with code again. No I was not able to

I called this function :

void our_service_change(ble_os_t * p_our_service)
{
uint32_t err_code_2;

static uint16_t start_handle= 0x000B;
const uint16_t end_handle = 0xFFFF;

err_code_2 = sd_ble_gatts_service_changed(p_our_service->conn_handle,
start_handle,
end_handle);

APP_ERROR_CHECK(err_code_2);
}

but its showing 12291 error, 12291 = 0x3003 and it's equal to BLE_ERROR_INVALID_ATTR_HANDLE.

I am using following code to add characteristics:

static uint32_t our_char_add(ble_os_t * p_our_service)
{

uint32_t err_code;
ble_uuid_t char_uuid;
ble_uuid128_t base_uuid = BLE_UUID_OUR_BASE_UUID;
char_uuid.uuid = BLE_UUID_OUR_CHARACTERISTC_UUID;
err_code = sd_ble_uuid_vs_add(&base_uuid, &char_uuid.type);
APP_ERROR_CHECK(err_code);


ble_gatts_char_md_t char_md;
memset(&char_md, 0, sizeof(char_md));
char_md.char_props.read = 1;
char_md.char_props.write = 1;


ble_gatts_attr_md_t cccd_md;
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;
char_md.p_cccd_md = &cccd_md;
char_md.char_props.notify = 1;




ble_gatts_attr_md_t attr_md;
memset(&attr_md, 0, sizeof(attr_md));
attr_md.vloc = BLE_GATTS_VLOC_STACK;



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


ble_gatts_attr_t attr_char_value;
memset(&attr_char_value, 0, sizeof(attr_char_value));
attr_char_value.p_uuid = &char_uuid;
attr_char_value.p_attr_md = &attr_md;


attr_char_value.max_len = 4;
attr_char_value.init_len = 4;
uint8_t value[4] = {0x12,0x34,0x56,0x78};
attr_char_value.p_value = value;


err_code = sd_ble_gatts_characteristic_add(p_our_service->service_handle,
&char_md,
&attr_char_value,
&p_our_service->char_handles);
APP_ERROR_CHECK(err_code);
return NRF_SUCCESS;
}

RE: How to indicate of new characteristics to client without refreshing the nrf connect app in nrf ble?

Karl Ylvisaker — Wed, 26 Jul 2023 10:46:42 GMT

Hello,

Please elaborate - were you successful in prompting a rediscovery, or did you encounter any issues or questions?
Please also use the Insert -> Code option when sharing code here on DevZone.

Best regards,
Karl

RE: How to indicate of new characteristics to client without refreshing the nrf connect app in nrf ble?

Ayu7 — Wed, 26 Jul 2023 09:27:25 GMT

Hi, I called this function :

void our_service_change(ble_os_t * p_our_service)
{
uint32_t err_code_2;

static uint16_t start_handle= 0x000B;
const uint16_t end_handle = 0xFFFF;

err_code_2 = sd_ble_gatts_service_changed(p_our_service->conn_handle,
start_handle,
end_handle);

APP_ERROR_CHECK(err_code_2);
}

but its showing 12291 error, 12291 = 0x3003 and it's equal to BLE_ERROR_INVALID_ATTR_HANDLE.

I am using following code to add characteristics:

static uint32_t our_char_add(ble_os_t * p_our_service)
{

uint32_t err_code;
ble_uuid_t char_uuid;
ble_uuid128_t base_uuid = BLE_UUID_OUR_BASE_UUID;
char_uuid.uuid = BLE_UUID_OUR_CHARACTERISTC_UUID;
err_code = sd_ble_uuid_vs_add(&base_uuid, &char_uuid.type);
APP_ERROR_CHECK(err_code);

ble_gatts_char_md_t char_md;
memset(&char_md, 0, sizeof(char_md));
char_md.char_props.read = 1;
char_md.char_props.write = 1;

ble_gatts_attr_md_t cccd_md;
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;
char_md.p_cccd_md = &cccd_md;
char_md.char_props.notify = 1;

ble_gatts_attr_md_t attr_md;
memset(&attr_md, 0, sizeof(attr_md));
attr_md.vloc = BLE_GATTS_VLOC_STACK;

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

ble_gatts_attr_t attr_char_value;
memset(&attr_char_value, 0, sizeof(attr_char_value));
attr_char_value.p_uuid = &char_uuid;
attr_char_value.p_attr_md = &attr_md;

attr_char_value.max_len = 4;
attr_char_value.init_len = 4;
uint8_t value[4] = {0x12,0x34,0x56,0x78};
attr_char_value.p_value = value;

err_code = sd_ble_gatts_characteristic_add(p_our_service->service_handle,
&char_md,
&attr_char_value,
&p_our_service->char_handles);
APP_ERROR_CHECK(err_code);
return NRF_SUCCESS;
}

RE: How to indicate of new characteristics to client without refreshing the nrf connect app in nrf ble?

Karl Ylvisaker — Wed, 26 Jul 2023 08:07:42 GMT

Hello,

To do this you will need to use the Services Changed notification - this lets your peripheral tell the central that there has been a change to the services / characteristics, and thus prompts the central to do a new discovery.

Please give this a try, and dont hesitate to let me know if you should encounter any issues or questions! :)

Best regards,
Karl