app_usbd_cdc_acm_write multiple write

[kleanthise]

Hello i am using an nrf52840 s140 and i am trying to write a specific event when takes place to the usb port. I am using the usbd_uart example. 

It works fine for the first write command but when i am trying to write for a second time it just writes random stuff.

i am basically updating the value of a characteristic using a counter and i would like that value of the counter to be transferred over to usb virtual port

Looking forward for your help on this

#include "sdk_common.h"
#if NRF_MODULE_ENABLED(BLE_NUS)
#include "ble.h"
#include "ble_nus_custom.h"
#include "ble_srv_common.h"

#define NRF_LOG_MODULE_NAME ble_nus
#if BLE_NUS_CONFIG_LOG_ENABLED
#define NRF_LOG_LEVEL BLE_NUS_CONFIG_LOG_LEVEL
#define NRF_LOG_INFO_COLOR BLE_NUS_CONFIG_INFO_COLOR
#define NRF_LOG_DEBUG_COLOR BLE_NUS_CONFIG_DEBUG_COLOR
#else // BLE_NUS_CONFIG_LOG_ENABLED
#define NRF_LOG_LEVEL 0
#endif // BLE_NUS_CONFIG_LOG_ENABLED
#include "nrf_log.h"
NRF_LOG_MODULE_REGISTER();

#define BLE_UUID_NUS_TX_CHARACTERISTIC 0x0003 /**< The UUID of the TX Characteristic. */
#define BLE_UUID_NUS_RX_CHARACTERISTIC 0x0002 /**< The UUID of the RX Characteristic. */
#define PROGRESS_VALUE_CHAR_UUID 0x0004	      /**< The UUID for Progress Characteristic */
#define RESULTS_VALUE_CHAR_UUID 0x0005	      /**< The UUID for Results Characteristic */

#define BLE_NUS_MAX_RX_CHAR_LEN BLE_NUS_MAX_DATA_LEN /**< Maximum length of the RX Characteristic (in bytes). */
#define BLE_NUS_MAX_TX_CHAR_LEN BLE_NUS_MAX_DATA_LEN /**< Maximum length of the TX Characteristic (in bytes). */

#define NUS_BASE_UUID                                                                                                  \
	{                                                                                                              \
		{                                                                                                      \
			0x9E, 0xCA, 0xDC, 0x24, 0x0E, 0xE5, 0xA9, 0xE0, 0x93, 0xF3, 0xA3, 0xB5, 0x00, 0x00, 0x40, 0x6E \
		}                                                                                                      \
	} /**< Used vendor specific UUID. */

/**@brief Function for handling the @ref BLE_GAP_EVT_CONNECTED event from the SoftDevice.
 *
 * @param[in] p_nus     Nordic UART Service structure.
 * @param[in] p_ble_evt Pointer to the event received from BLE stack.
 */
static void on_connect(ble_nus_t *p_nus, ble_evt_t const *p_ble_evt)
{
	ret_code_t err_code;
	ble_nus_evt_t evt;
	ble_gatts_value_t gatts_val;
	uint8_t cccd_value[2];
	ble_nus_client_context_t *p_client = NULL;

	err_code = blcm_link_ctx_get(p_nus->p_link_ctx_storage,
	    p_ble_evt->evt.gap_evt.conn_handle,
	    (void *)&p_client);
	if (err_code != NRF_SUCCESS) {
		NRF_LOG_ERROR("Link context for 0x%02X connection handle could not be fetched.",
		    p_ble_evt->evt.gap_evt.conn_handle);
	}

	/* Check the hosts CCCD value to inform of readiness to send data using the RX characteristic */
	memset(&gatts_val, 0, sizeof(ble_gatts_value_t));
	gatts_val.p_value = cccd_value;
	gatts_val.len = sizeof(cccd_value);
	gatts_val.offset = 0;

	err_code = sd_ble_gatts_value_get(p_ble_evt->evt.gap_evt.conn_handle,
	    p_nus->tx_handles.cccd_handle,
	    &gatts_val);

	if ((err_code == NRF_SUCCESS) &&
	    (p_nus->data_handler != NULL) &&
	    ble_srv_is_notification_enabled(gatts_val.p_value)) {
		if (p_client != NULL) {
			p_client->is_notification_enabled = true;
		}

		memset(&evt, 0, sizeof(ble_nus_evt_t));
		evt.type = BLE_NUS_EVT_COMM_STARTED;
		evt.p_nus = p_nus;
		evt.conn_handle = p_ble_evt->evt.gap_evt.conn_handle;
		evt.p_link_ctx = p_client;

		p_nus->data_handler(&evt);
	}
}

/**@brief Function for handling the @ref BLE_GATTS_EVT_WRITE event from the SoftDevice.
 *
 * @param[in] p_nus     Nordic UART Service structure.
 * @param[in] p_ble_evt Pointer to the event received from BLE stack.
 */
static void on_write(ble_nus_t *p_nus, ble_evt_t const *p_ble_evt)
{
	ret_code_t err_code;
	ble_nus_evt_t evt;
	ble_nus_client_context_t *p_client;
	ble_gatts_evt_write_t const *p_evt_write = &p_ble_evt->evt.gatts_evt.params.write;

	err_code = blcm_link_ctx_get(p_nus->p_link_ctx_storage,
	    p_ble_evt->evt.gatts_evt.conn_handle,
	    (void *)&p_client);
	if (err_code != NRF_SUCCESS) {
		NRF_LOG_ERROR("Link context for 0x%02X connection handle could not be fetched.",
		    p_ble_evt->evt.gatts_evt.conn_handle);
	}

	memset(&evt, 0, sizeof(ble_nus_evt_t));
	evt.p_nus = p_nus;
	evt.conn_handle = p_ble_evt->evt.gatts_evt.conn_handle;
	evt.p_link_ctx = p_client;

	if ((p_evt_write->handle == p_nus->tx_handles.cccd_handle) &&
	    (p_evt_write->len == 2)) {
		if (p_client != NULL) {
			if (ble_srv_is_notification_enabled(p_evt_write->data)) {
				p_client->is_notification_enabled = true;
				evt.type = BLE_NUS_EVT_COMM_STARTED;
			} else {
				p_client->is_notification_enabled = false;
				evt.type = BLE_NUS_EVT_COMM_STOPPED;
			}

			if (p_nus->data_handler != NULL) {
				p_nus->data_handler(&evt);
			}
		}
	} else if ((p_evt_write->handle == p_nus->rx_handles.value_handle) &&
		   (p_nus->data_handler != NULL)) {
		evt.type = BLE_NUS_EVT_RX_DATA;
		evt.params.rx_data.p_data = p_evt_write->data;
		evt.params.rx_data.length = p_evt_write->len;

		p_nus->data_handler(&evt);
	} else {
		// Do Nothing. This event is not relevant for this service.
	}
}

/**@brief Function for handling the @ref BLE_GATTS_EVT_HVN_TX_COMPLETE event from the SoftDevice.
 *
 * @param[in] p_nus     Nordic UART Service structure.
 * @param[in] p_ble_evt Pointer to the event received from BLE stack.
 */
static void on_hvx_tx_complete(ble_nus_t *p_nus, ble_evt_t const *p_ble_evt)
{
	ret_code_t err_code;
	ble_nus_evt_t evt;
	ble_nus_client_context_t *p_client;

	err_code = blcm_link_ctx_get(p_nus->p_link_ctx_storage,
	    p_ble_evt->evt.gatts_evt.conn_handle,
	    (void *)&p_client);
	if (err_code != NRF_SUCCESS) {
		NRF_LOG_ERROR("Link context for 0x%02X connection handle could not be fetched.",
		    p_ble_evt->evt.gatts_evt.conn_handle);
		return;
	}

	if ((p_client->is_notification_enabled) && (p_nus->data_handler != NULL)) {
		memset(&evt, 0, sizeof(ble_nus_evt_t));
		evt.type = BLE_NUS_EVT_TX_RDY;
		evt.p_nus = p_nus;
		evt.conn_handle = p_ble_evt->evt.gatts_evt.conn_handle;
		evt.p_link_ctx = p_client;

		p_nus->data_handler(&evt);
	}
}

void ble_nus_on_ble_evt(ble_evt_t const *p_ble_evt, void *p_context)
{
	if ((p_context == NULL) || (p_ble_evt == NULL)) {
		return;
	}

	ble_nus_t *p_nus = (ble_nus_t *)p_context;

	switch (p_ble_evt->header.evt_id) {
	case BLE_GAP_EVT_CONNECTED:
		on_connect(p_nus, p_ble_evt);
		break;

	case BLE_GATTS_EVT_WRITE:
		on_write(p_nus, p_ble_evt);
		break;

	case BLE_GATTS_EVT_HVN_TX_COMPLETE:
		on_hvx_tx_complete(p_nus, p_ble_evt);
		break;

	default:
		// No implementation needed.
		break;
	}
}

// Add the RX Characteristic.

static uint32_t rx_char_add(ble_nus_t *p_nus, const ble_nus_init_t *p_nus_init)
{
	uint32_t err_code;
	ble_gatts_char_md_t char_md;
	ble_gatts_attr_md_t cccd_md;
	ble_gatts_attr_md_t attr_md;
	ble_gatts_attr_t attr_char_value;
	ble_uuid_t ble_uuid;

	// Initiliaze the structures
	memset(&cccd_md, 0, sizeof(cccd_md));
	memset(&char_md, 0, sizeof(char_md));
	memset(&attr_md, 0, sizeof(attr_md));
	memset(&attr_char_value, 0, sizeof(attr_char_value));

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

	// Client Characteristic Configuration Descriptor metadata.
	cccd_md.vloc = BLE_GATTS_VLOC_STACK; // decide where to store the descriptor (the value of the CCCD), and once again we store it in the SoftDevice controlled part of memory (as we did with the characteristic)
	char_md.char_props.read = 0;	     // Enable read
	char_md.char_props.write = 1;	     // Enable write
	char_md.char_props.write_wo_resp = 1;
	char_md.char_props.notify = 0; // Enable notifications
	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_nus->uuid_type;
	ble_uuid.uuid = BLE_UUID_NUS_RX_CHARACTERISTIC;

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

	attr_md.read_perm = p_nus_init->rx_char_attr_md.read_perm;
	attr_md.write_perm = p_nus_init->rx_char_attr_md.write_perm;
	attr_md.vloc = BLE_GATTS_VLOC_STACK; // BLE_GATTS_VLOC_STACK is the memory location (stack memory) to store the attributes (characteristic)
	attr_md.rd_auth = 0;
	attr_md.wr_auth = 0;
	attr_md.vlen = 0;

	attr_char_value.p_uuid = &ble_uuid;
	attr_char_value.p_attr_md = &attr_md;
	attr_char_value.init_len = sizeof(uint8_t); // sizeof(uint8_t);
	attr_char_value.init_offs = 0;
	attr_char_value.max_len = BLE_NUS_MAX_RX_CHAR_LEN; // sizeof(uint8_t);

	err_code = sd_ble_gatts_characteristic_add(p_nus->service_handle, &char_md, &attr_char_value, &p_nus->rx_handles);
	if (err_code != NRF_SUCCESS) {
		return err_code;
	}

	return NRF_SUCCESS;
}

// Add the TX Characteristic.

static uint32_t tx_char_add(ble_nus_t *p_nus, const ble_nus_init_t *p_nus_init)
{
	uint32_t err_code;
	ble_gatts_char_md_t char_md;
	ble_gatts_attr_md_t cccd_md;
	ble_gatts_attr_md_t attr_md;
	ble_gatts_attr_t attr_char_value;
	ble_uuid_t ble_uuid;

	// Initiliaze the structures
	memset(&cccd_md, 0, sizeof(cccd_md));
	memset(&char_md, 0, sizeof(char_md));
	memset(&attr_md, 0, sizeof(attr_md));
	memset(&attr_char_value, 0, sizeof(attr_char_value));

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

	// Client Characteristic Configuration Descriptor metadata.
	cccd_md.vloc = BLE_GATTS_VLOC_STACK; // decide where to store the descriptor (the value of the CCCD), and once again we store it in the SoftDevice controlled part of memory (as we did with the characteristic)
	char_md.char_props.read = 1;	     // Enable read
	char_md.char_props.notify = 1;	     // Enable notifications
	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_nus->uuid_type;
	ble_uuid.uuid = BLE_UUID_NUS_TX_CHARACTERISTIC;

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

	attr_md.read_perm = p_nus_init->tx_char_attr_md.read_perm;
	attr_md.write_perm = p_nus_init->tx_char_attr_md.write_perm;
	attr_md.vloc = BLE_GATTS_VLOC_STACK; // BLE_GATTS_VLOC_STACK is the memory location (stack memory) to store the attributes (characteristic)
	attr_md.rd_auth = 0;
	attr_md.wr_auth = 0;
	attr_md.vlen = 0;

	attr_char_value.p_uuid = &ble_uuid;
	attr_char_value.p_attr_md = &attr_md;
	attr_char_value.init_len = sizeof(uint8_t); // sizeof(uint8_t);
	attr_char_value.init_offs = 0;
	attr_char_value.max_len = BLE_NUS_MAX_TX_CHAR_LEN; // sizeof(uint8_t);

	err_code = sd_ble_gatts_characteristic_add(p_nus->service_handle, &char_md, &attr_char_value, &p_nus->tx_handles);
	if (err_code != NRF_SUCCESS) {
		return err_code;
	}

	return NRF_SUCCESS;
}

// Add the Progress Characteristic.

static uint32_t progress_char_add(ble_nus_t *p_nus, const ble_nus_init_t *p_nus_init)
{
	uint32_t err_code;
	ble_gatts_char_md_t char_md;
	ble_gatts_attr_md_t cccd_md;
	ble_gatts_attr_md_t attr_md;
	ble_gatts_attr_t attr_char_value;
	ble_uuid_t ble_uuid;

	// Initiliaze the structures
	memset(&cccd_md, 0, sizeof(cccd_md));
	memset(&char_md, 0, sizeof(char_md));
	memset(&attr_md, 0, sizeof(attr_md));
	memset(&attr_char_value, 0, sizeof(attr_char_value));

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

	// Client Characteristic Configuration Descriptor metadata.
	cccd_md.vloc = BLE_GATTS_VLOC_STACK; // decide where to store the descriptor (the value of the CCCD), and once again we store it in the SoftDevice controlled part of memory (as we did with the characteristic)
	char_md.char_props.read = 1;	     // Enable read
	char_md.char_props.notify = 1;	     // Enable notifications
	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_nus->uuid_type;
	ble_uuid.uuid = PROGRESS_VALUE_CHAR_UUID;

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

	attr_md.read_perm = p_nus_init->progress_char_attr_md.read_perm;
	attr_md.write_perm = p_nus_init->progress_char_attr_md.write_perm;
	attr_md.vloc = BLE_GATTS_VLOC_STACK; // BLE_GATTS_VLOC_STACK is the memory location (stack memory) to store the attributes (characteristic)
	attr_md.rd_auth = 0;
	attr_md.wr_auth = 0;
	attr_md.vlen = 0;

	attr_char_value.p_uuid = &ble_uuid;
	attr_char_value.p_attr_md = &attr_md;
	attr_char_value.init_len = sizeof(uint8_t); // sizeof(uint8_t);
	attr_char_value.init_offs = 0;
	attr_char_value.max_len = sizeof(uint8_t); // sizeof(uint8_t);

	err_code = sd_ble_gatts_characteristic_add(p_nus->service_handle, &char_md, &attr_char_value, &p_nus->progress_handles);
	if (err_code != NRF_SUCCESS) {
		return err_code;
	}

	return NRF_SUCCESS;
}

// Add the Results Characteristic.

static uint32_t results_char_add(ble_nus_t *p_nus, const ble_nus_init_t *p_nus_init)
{
	uint32_t err_code;
	ble_gatts_char_md_t char_md;
	ble_gatts_attr_md_t cccd_md;
	ble_gatts_attr_md_t attr_md;
	ble_gatts_attr_t attr_char_value;
	ble_uuid_t ble_uuid;

	// Initiliaze the structures
	memset(&cccd_md, 0, sizeof(cccd_md));
	memset(&char_md, 0, sizeof(char_md));
	memset(&attr_md, 0, sizeof(attr_md));
	memset(&attr_char_value, 0, sizeof(attr_char_value));

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

	// Client Characteristic Configuration Descriptor metadata.
	cccd_md.vloc = BLE_GATTS_VLOC_STACK; // decide where to store the descriptor (the value of the CCCD), and once again we store it in the SoftDevice controlled part of memory (as we did with the characteristic)
	char_md.char_props.read = 1;	     // Enable read
	char_md.char_props.notify = 1;	     // Enable notifications
	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_nus->uuid_type;
	ble_uuid.uuid = RESULTS_VALUE_CHAR_UUID;

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

	attr_md.read_perm = p_nus_init->results_char_attr_md.read_perm;
	attr_md.write_perm = p_nus_init->results_char_attr_md.write_perm;
	attr_md.vloc = BLE_GATTS_VLOC_STACK; // BLE_GATTS_VLOC_STACK is the memory location (stack memory) to store the attributes (characteristic)
	attr_md.rd_auth = 0;
	attr_md.wr_auth = 0;
	attr_md.vlen = 0;

	attr_char_value.p_uuid = &ble_uuid;
	attr_char_value.p_attr_md = &attr_md;
	attr_char_value.init_len = 8; // sizeof(uint8_t);
	attr_char_value.init_offs = 0;
	attr_char_value.max_len = 8; // sizeof(uint8_t);

	err_code = sd_ble_gatts_characteristic_add(p_nus->service_handle, &char_md, &attr_char_value, &p_nus->results_handles);
	if (err_code != NRF_SUCCESS) {
		return err_code;
	}

	return NRF_SUCCESS;
}

// This is where we will implement the notification
uint32_t ble_progress_update(ble_nus_t *p_nus, uint8_t custom_value)
{
	NRF_LOG_INFO("In ble_cus_custom_value_update. \r\n");
	if (p_nus == NULL) {
		return NRF_ERROR_NULL;
	}

	uint32_t err_code = NRF_SUCCESS;
	ble_gatts_value_t gatts_value;
	ble_nus_evt_t evt;

	// Initialize value struct.
	memset(&gatts_value, 0, sizeof(gatts_value));

	gatts_value.len = sizeof(custom_value);
	gatts_value.offset = 0;
	gatts_value.p_value = &custom_value;

	// Update database.
	err_code = sd_ble_gatts_value_set(p_nus->conn_handle,
	    p_nus->progress_handles.value_handle,
	    &gatts_value);
	if (err_code != NRF_SUCCESS) {
		return err_code;
	}

	// Send value if connected and notifying.
	if ((p_nus->conn_handle != BLE_CONN_HANDLE_INVALID)) {
		ble_gatts_hvx_params_t hvx_params;

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

		hvx_params.handle = p_nus->progress_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_nus->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");
	}
	evt.type = UART_RX_DATA;
	NRF_LOG_INFO("Event type: %d", evt.type);
	p_nus->data_handler(&evt);

	return err_code;
}

uint32_t ble_results_update(ble_nus_t *p_nus, uint8_t *results_value)
{
	NRF_LOG_INFO("In ble_cus_results_value_update. \r\n");
	if (p_nus == 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 = sizeof(results_value);
	gatts_value.offset = 0;
	gatts_value.p_value = results_value;

	// Update database.
	err_code = sd_ble_gatts_value_set(p_nus->conn_handle,
	    p_nus->results_handles.value_handle,
	    &gatts_value);
	if (err_code != NRF_SUCCESS) {
		return err_code;
	}

	// Send value if connected and notifying.
	if ((p_nus->conn_handle != BLE_CONN_HANDLE_INVALID)) {
		ble_gatts_hvx_params_t hvx_params;

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

		hvx_params.handle = p_nus->results_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_nus->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;
}

uint32_t ble_nus_init(ble_nus_t *p_nus, ble_nus_init_t const *p_nus_init)
{
	ret_code_t err_code;
	ble_uuid_t ble_uuid;
	ble_uuid128_t nus_base_uuid = NUS_BASE_UUID;
	ble_add_char_params_t add_char_params;

	VERIFY_PARAM_NOT_NULL(p_nus);
	VERIFY_PARAM_NOT_NULL(p_nus_init);

	// Initialize the service structure.
	p_nus->data_handler = p_nus_init->data_handler;

	/**@snippet [Adding proprietary Service to the SoftDevice] */
	// Add a custom base UUID.
	err_code = sd_ble_uuid_vs_add(&nus_base_uuid, &p_nus->uuid_type);
	VERIFY_SUCCESS(err_code);

	ble_uuid.type = p_nus->uuid_type;
	ble_uuid.uuid = BLE_UUID_NUS_SERVICE;

	// Add the service.
	err_code = sd_ble_gatts_service_add(BLE_GATTS_SRVC_TYPE_PRIMARY,
	    &ble_uuid,
	    &p_nus->service_handle);
	/**@snippet [Adding proprietary Service to the SoftDevice] */
	VERIFY_SUCCESS(err_code);

	err_code = rx_char_add(p_nus, p_nus_init);
	if (err_code != NRF_SUCCESS) {
		return err_code;
	}

	err_code = tx_char_add(p_nus, p_nus_init);
	if (err_code != NRF_SUCCESS) {
		return err_code;
	}

	err_code = progress_char_add(p_nus, p_nus_init);
	if (err_code != NRF_SUCCESS) {
		return err_code;
	}

	err_code = results_char_add(p_nus, p_nus_init);
	if (err_code != NRF_SUCCESS) {
		return err_code;
	}
}

uint32_t ble_nus_data_send(ble_nus_t *p_nus,
    uint8_t *p_data,
    uint16_t *p_length,
    uint16_t conn_handle)
{
	ret_code_t err_code;
	ble_gatts_hvx_params_t hvx_params;
	ble_nus_client_context_t *p_client;

	VERIFY_PARAM_NOT_NULL(p_nus);

	err_code = blcm_link_ctx_get(p_nus->p_link_ctx_storage, conn_handle, (void *)&p_client);
	VERIFY_SUCCESS(err_code);

	if ((conn_handle == BLE_CONN_HANDLE_INVALID) || (p_client == NULL)) {
		return NRF_ERROR_NOT_FOUND;
	}

	if (!p_client->is_notification_enabled) {
		return NRF_ERROR_INVALID_STATE;
	}

	if (*p_length > BLE_NUS_MAX_DATA_LEN) {
		return NRF_ERROR_INVALID_PARAM;
	}

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

	hvx_params.handle = p_nus->tx_handles.value_handle;
	hvx_params.p_data = p_data;
	hvx_params.p_len = p_length;
	hvx_params.type = BLE_GATT_HVX_NOTIFICATION;

	return sd_ble_gatts_hvx(conn_handle, &hvx_params);
}

#endif // NRF_MODULE_ENABLED(BLE_NUS)

[Einar Thorsrud]

Where should this be printed? What you do here (except for the issues described in my previous post) is to take the integer value in the counter variable and convert it to a string in the buf char array. So now it resides as a C string in buf. But it is not printed by itself unless you do so.

[kleanthise]

This should be transferred over to the usb and printed on my computer terminal. I thought that this command : ret = app_usbd_cdc_acm_write(&m_app_cdc_acm, buf, j); would transfer the data over to my usb port and be printed on the terminal but this is not the case.

Is it correct the way i understood it ? or shall i use a different command to print the data to my terminal connection ?

[Einar Thorsrud]

Hi,

The app_usbd_cdc_acm_write() will write to USB CDC ACM, yes. So you should see it on your computer (provided things are done correctly and you have a terminal on your computer connected to that virtual UART port). You can see a simple example of the same in examples/peripheral/usbd_cdc_acm/main.c:

            static int  frame_counter;

            size_t size = sprintf(m_tx_buffer, "Hello USB CDC FA demo: %u\r\n", frame_counter);

            ret = app_usbd_cdc_acm_write(&m_app_cdc_acm, m_tx_buffer, size);
            if (ret == NRF_SUCCESS)
            {
                ++frame_counter;
            }

kleanthise said:

my terminal connection

If this is terminal via USB CDC ACM, then the above is the way to do it. If it is via UART or NUS, then other approaches are needed (see relevant samples for that). You have most of the code in your project though, the main thing should be to fix up the generic C programming mistakes we have discussed before in this thread.

[kleanthise]

Thanks a lot i have modified the code and now the counter is printed over to terminal. However the string is presented as an ascii. Is there a way to convert it to hex ? 

I have for example one condition in hex that is the command activation (0x01) when the user sends that command via BLE the code is activated and it runs a sequence. However when i switch my terminal to ascii i can only monitor the commands received from the counter and not the starting command. Is there a way to print the hex command while looking at ascii characters ? 

[Einar Thorsrud]

Convert the hex data to ascii(for instance using snprintf) so that everything you send to the terminal is ascii