Disconnection request from peripheral device.

[viswa]

Hi Everyone,

sdk : nrf Connect v1.7.0

ide : VS code

I was trying out central_hr sample on nrf52840 dk. I have simulated hrs server in nrf Connect mobile application. So basically our dk is Central and nrf Connect app is peripheral here.

Suppose I have disconnected in nrf Connect app,after central made a connection, I couldn't see any callback related to disconnection on central side.

This isn't the case with peripheral_hr sample in nrf52dk. 

My question is ...

1.How the Central device knows if the peripheral is still in connection?

2.Can we disconnect from peripheral side in a ble connection?

3.Suppose I have both functionalities central and peripheral running parallely in a nrf52 chip, how to handle connection and disconnection from two independent roles?

[Simonr]

Hi

Most of the central applications in the nRFConnect SDK (NCS) handle disconnections with a disconnected event similar to this, so you should get a "Disconnected" logging message: 

static void disconnected(struct bt_conn *conn, uint8_t reason)
{
	int err;
	char addr[BT_ADDR_LE_STR_LEN];

	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));

	printk("Disconnected: %s (reason 0x%02x)\n", addr, reason);

	if (default_conn != conn) {
		return;
	}

	bt_conn_unref(default_conn);
	default_conn = NULL;

	err = bt_scan_start(BT_SCAN_TYPE_SCAN_ACTIVE);
	if (err) {
		printk("Scanning failed to start (err %d)\n", err);
	}
}

Generally I think most central applications have a button assigned to disconnect from peripherals, alternatively they'll disconnect automatically when the connection supervision timeout is exceeded.

Best regards,

Simon

[viswa]

yeah, I've waited for 10minutes long,

/******** My change to central_hr sample code ****************/

static bool eir_found(struct bt_data *data, void *user_data)
{
	bt_addr_le_t *addr = user_data;
	int i;
    uint8_t array[20] = {0};
	printk("[AD]: %u data_len %u\n", data->type, data->data_len);

	switch (data->type) {
	case BT_DATA_UUID16_SOME:
	case BT_DATA_UUID16_ALL:
		if (data->data_len % sizeof(uint16_t) != 0U) {
			printk("AD malformed\n");
			return true;
		}

		for (i = 0; i < data->data_len; i += sizeof(uint16_t)) {
			struct bt_le_conn_param *param;
			struct bt_uuid *uuid;
			uint16_t u16;
			int err;

			memcpy(&u16, &data->data[i], sizeof(u16));
			uuid = BT_UUID_DECLARE_16(sys_le16_to_cpu(u16));
			if (bt_uuid_cmp(uuid, BT_UUID_HRS)) {
				continue;
			}

			err = bt_le_scan_stop();
			if (err) {
				printk("Stop LE scan failed (err %d)\n", err);
				continue;
			}

			param = BT_LE_CONN_PARAM_DEFAULT;
			err = bt_conn_le_create(addr, BT_CONN_LE_CREATE_CONN,
						param, &default_conn);
			if (err) {
				printk("Create conn failed (err %d)\n", err);
				// bt_start_scan();
			}

			return false;
		}
	break;
	case BT_DATA_NAME_COMPLETE:
			
	memcpy(array, data->data,data->data_len);
	printk("Complete local Name: %s\r\n",array);
	if(strcmp(array,"Viswa's A52") == 0)
	{
	int err = bt_le_scan_stop();
	printk("BLE SCAN STOP\r\n");
			if (err) {
				printk("Stop LE scan failed (err %d)\n", err);
				// continue;
			}
			struct bt_le_conn_param *param;
			struct bt_uuid *uuid;
			param = BT_LE_CONN_PARAM_DEFAULT;
			err = bt_conn_le_create(addr, BT_CONN_LE_CREATE_CONN,
						param, &default_conn);
			if (err) {
				printk("Create conn failed (err %d)\n", err);
				// bt_start_scan();
			}
			return false;
	}
		break;
	}

	return true;                   
	
}

but in my case I couldn't see the callback triggered. the only change i did is to start connection based on "complete local name 0x09 flag" from advertising parameters into existing central_hr  sample code.

I have commented the discovery of services part too. Now the client simply connects. I have registered disconnect callbacks so i expect, it should be triggered.

please clarify my doubt below

Can we disconnect from peripheral side in a ble connection?

i