Hi,
I have been working on nRF since last week now. I've followed the tutorials on how to setup a custom service and custom characterics (Bluetooth low energy Services, a beginner's tutorial and Bluetooth low energy Characteristics, a beginner's tutorial). After setting up, I wanted to do my own thing, but I have been hitting a wall for a day now and I still don't know how to move on.
I'm working on the BLE_peripheral example of the heart rate service and I added the NUS example as well. I've also added a custom service and what I am trying to do is to send a payload of 69 bytes to a custom characteristic upon the writing of a character on the serial port (see code below).
/**@brief Function for handling app_uart events.
*
* @details This function will receive a single character from the app_uart module and append it to
* a string. The string will be be sent over BLE when the last character received was a
* 'new line' '\n' (hex 0x0A) or if the string has reached the maximum data length.
*/
/**@snippet [Handling the data received over UART] */
void uart_event_handle(app_uart_evt_t * p_event)
{
static uint8_t data_array[BLE_NUS_MAX_DATA_LEN];
static uint8_t index = 0;
uint32_t err_code;
switch (p_event->evt_type)
{
case APP_UART_DATA_READY:
UNUSED_VARIABLE(app_uart_get(&data_array[index]));
index++;
if ((data_array[index - 1] == '\n') ||
(data_array[index - 1] == '\r') ||
(index >= m_ble_nus_max_data_len))
{
if (index > 1)
{
NRF_LOG_DEBUG("Ready to send data over BLE NUS");
NRF_LOG_HEXDUMP_DEBUG(data_array, index);
do
{
uint16_t length = (uint16_t)index;
err_code = ble_nus_data_send(&m_nus, data_array, &length, m_conn_handle);
if ((err_code != NRF_ERROR_INVALID_STATE) &&
(err_code != NRF_ERROR_RESOURCES) &&
(err_code != NRF_ERROR_NOT_FOUND))
{
APP_ERROR_CHECK(err_code);
}
} while (err_code == NRF_ERROR_RESOURCES);
}
index = 0;
}
//custom code
else if ((data_array[index - 1] == 'c'))
{
index = 69;
uint16_t length = (uint16_t)index;
uint8_t data[index];
memset(data, 0, index);
data[0] = 0x01;
data[3] = 0x18;
data[4] = 0x42;
err_code = ble_nus_data_send(&m_nus, data, &length, m_conn_handle);
if ((err_code != NRF_ERROR_INVALID_STATE) &&
(err_code != NRF_ERROR_RESOURCES) &&
(err_code != NRF_ERROR_NOT_FOUND))
{
APP_ERROR_CHECK(err_code);
}
characteristic_data_update(&m_my_service, m_conn_handle, data, &length);
index = 0;
}
break;
case APP_UART_COMMUNICATION_ERROR:
APP_ERROR_HANDLER(p_event->data.error_communication);
break;
case APP_UART_FIFO_ERROR:
APP_ERROR_HANDLER(p_event->data.error_code);
break;
default:
break;
}
}
/**@snippet [Handling the data received over UART] */
void characteristic_data_update(ble_ms_t *p_my_service, uint16_t conn_handle, uint8_t* data, uint16_t* length)
{
if (conn_handle != BLE_CONN_HANDLE_INVALID)
{
//uint16_t len = length;
ble_gatts_hvx_params_t hvx_params;
memset(&hvx_params, 0, sizeof(hvx_params));
hvx_params.handle = p_my_service->device_control_handles.value_handle;
hvx_params.type = BLE_GATT_HVX_NOTIFICATION;
hvx_params.offset = 0;
hvx_params.p_len = length;
hvx_params.p_data = data;
sd_ble_gatts_hvx(conn_handle, &hvx_params);
}
}
I have added a condition where on 'c' character input it sends a payload full of 0x00 except for 3 bytes. The payload works just fine with the NUS service, but it starts to get itchy when it comes to the custom service. The first 8 bytes (sometimes the first 16 bytes) repeat themselves for the entire length of the payload. I suspected first my parameters but then I took the same as the NUS function, still the same problem. I also checked for parameters in sdk_config.h file like ATT_MTU but the value seems fine.
On the debugger; I looked for length pointer value once it is returned by hvx_params struct, and it said 8 but still wrote 69 bytes on the characteristic.
I work on Windows 10 with nRF52840 DK with nRF Connect for Mobile on my Android. My SDK is v17.0.2 and my softdevice is the pca10056.
Screens :
Thanks in advance for any tips that might help me.
FM
