Hi,
I would like to increase the length of read & write characteristic value to 29 bytes. I changed the NRF_SDH_BLE_GAP_DATA_LENGTH = 36 & NRF_SDH_BLE_GATT_MAX_MTU_SIZE = 32. Also changed attr_char_value.max_len = 29 & ram settings & hvx_params.p_len = &gatts_value.len. But on nrfconnect I could see only 22 bytes for read characteristic & 2 bytes for write characteristic. What am I missing?
Hi,
What SDK version and example do you use?
What is the value of &gatts_value.len?
Best regards,
Amanda
I'm using ble_app_template example in SDK 15.2.
I have set gatts_value.len = 29*sizeof(uint8_t);
uint32_t ble_midi_data_io_value_update(ble_midi_service_t * p_midi_service, uint8_t data_io_value[29])
{
if (p_midi_service == NULL)
{
return NRF_ERROR_NULL;
}
uint32_t err_code = NRF_SUCCESS;
ble_gatts_value_t gatts_value;
// Initialize value struct.
memset(&gatts_value, 0, sizeof(gatts_value));
gatts_value.len = 29*sizeof(uint8_t);
gatts_value.offset = 0;
gatts_value.p_value = &data_io_value[0];
// Update database.
err_code = sd_ble_gatts_value_set(p_midi_service->conn_handle, p_midi_service->data_io_char_handles.value_handle, &gatts_value);
if (err_code != NRF_SUCCESS)
{
return err_code;
}
// Send value if connected and notifying.
if ((p_midi_service->conn_handle != BLE_CONN_HANDLE_INVALID))
{
ble_gatts_hvx_params_t hvx_params;
memset(&hvx_params, 0, sizeof(hvx_params));
hvx_params.handle = p_midi_service->data_io_char_handles.value_handle;
hvx_params.type = BLE_GATT_HVX_NOTIFICATION;
hvx_params.offset = gatts_value.offset;
hvx_params.p_len = &gatts_value.len;
hvx_params.p_data = gatts_value.p_value;
err_code = sd_ble_gatts_hvx(p_midi_service->conn_handle, &hvx_params);
NRF_LOG_INFO("sd_ble_gatts_hvx result: %x. \r\n", err_code);
}
else
{
err_code = NRF_ERROR_INVALID_STATE;
NRF_LOG_INFO("sd_ble_gatts_hvx result: NRF_ERROR_INVALID_STATE. \r\n");
}
return err_code;
}
Please guide what else do I need to add?
Could you provide the code where you initializes the characteristic?
The code before sd_ble_gatts_characteristic_add ().
-Amanda
/**@brief Function for adding the Data I/O characteristic. */
static uint32_t data_io_char_add(ble_midi_service_t * p_midi_service, const ble_midi_service_init_t * p_midi_service_init)
{
uint32_t err_code;
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;
// Configure the CCCD which is needed for Notifications and Indications
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;
// Configure the characteristic metadata.
memset(&char_md, 0, sizeof(char_md));
char_md.char_props.read = 1;
char_md.char_props.write_wo_resp = 1;
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;
// Add the MIDI Data I/O Characteristic UUID
ble_uuid128_t base_uuid = {BLE_UUID_MIDI_DATA_IO_CHAR_BASE_UUID};
err_code = sd_ble_uuid_vs_add(&base_uuid, &p_midi_service->uuid_type);
if (err_code != NRF_SUCCESS)
{
return err_code;
}
ble_uuid.type = p_midi_service->uuid_type;
ble_uuid.uuid = BLE_UUID_MIDI_DATA_IO_CHAR_UUID;
// Configure the characteristic value's metadata
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 = 0;
// Configure the characteristic value
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 = sizeof(uint8_t);
attr_char_value.init_offs = 0;
attr_char_value.max_len = 29*sizeof(uint8_t);
attr_char_value.p_value = NULL;
return sd_ble_gatts_characteristic_add(p_midi_service->service_handle, &char_md, &attr_char_value, &p_midi_service->data_io_char_handles);
}
I am also attaching the full code for your reference. Please have a look.
Hi,
Change the Line 46 as
attr_char_value.init_len = 29*sizeof(uint8_t);
-Amanda