Getting strange RSSI values from Bluetooth scans

RE: Getting strange RSSI values from Bluetooth scans

Kenneth — Thu, 25 Sep 2025 12:00:03 GMT

Good to hear that the example works, I think you approach sounds like a good plan, closing case.

Kenneth

RE: Getting strange RSSI values from Bluetooth scans

Nicholas Robinson — Wed, 24 Sep 2025 15:09:47 GMT

I have tried to identify the difference(s) between my code and the working example. I can't see it. I think I will start again using the working example as a starting point! Thank you for your help.

RE: Getting strange RSSI values from Bluetooth scans

Nicholas Robinson — Wed, 24 Sep 2025 13:15:10 GMT

All devices are now showing good (and varying) RSSI values!

RE: Getting strange RSSI values from Bluetooth scans

Kenneth — Wed, 24 Sep 2025 12:24:40 GMT

Can you try opening the same example as me and replace scan_recv() as suggested to check on your end?

Kenneth

RE: Getting strange RSSI values from Bluetooth scans

Nicholas Robinson — Wed, 24 Sep 2025 12:13:29 GMT

Hello,

Thank you for looking at this. I am using an NRF54L15_xxAA_REV2 and v3.1.1 (zephyr 4.1.99).

RE: Getting strange RSSI values from Bluetooth scans

Kenneth — Wed, 24 Sep 2025 11:38:17 GMT

Hello,

I tried to recreate your problem by using \ncs\v3.1.0\nrf\samples\bluetooth\scanning_while_connecting\src\main.c with the following modification of scan_recv()

static void scan_recv(const struct bt_le_scan_recv_info *info, struct net_buf_simple *buf)
{
	/** We're only interested in connectable advertisers to
	 * show faster connection establishment
	 */
	if (info->adv_type != BT_GAP_ADV_TYPE_ADV_IND &&
		info->adv_type != BT_GAP_ADV_TYPE_EXT_ADV) {
		//return;
	}

	char name_str[ADV_NAME_STR_MAX_LEN] = {0};

	bt_data_parse(buf, adv_data_parse_cb, name_str);

	uint32_t current_time = k_uptime_get_32();
	char addr_str[BT_ADDR_LE_STR_LEN];
    bt_addr_le_to_str(info->addr, addr_str, sizeof(addr_str));

	static uint32_t total_scan_count;
	total_scan_count++;

	/* Log every scan for specific problematic device (using string comparison) */
    LOG_INF("PROBLEMATIC DEVICE SCAN: %s, RSSI: %hhd, Time: %u ms, Count: %u", 
                addr_str, info->rssi, current_time, total_scan_count);

	if (strncmp(name_str, adv_name, ADV_NAME_STR_MAX_LEN) == 0) {

		char addr_str[BT_ADDR_LE_STR_LEN] = {0};

		bt_addr_le_to_str(info->addr, addr_str, sizeof(addr_str));

		uint32_t bytes_written = cache_peer_address(info->addr);

		if (bytes_written > 0) {
			LOG_DBG("Scanned and cached connectable addr %s", addr_str);
		}

		try_connect();
	}
}

Though it seems to work as intended here:

What nRF54L15-DK are you using and which nRF Connect SDK are you using?

Kenneth

RE: Getting strange RSSI values from Bluetooth scans

Nicholas Robinson — Tue, 23 Sep 2025 16:00:47 GMT

My test is if (info->rssi > 0) and not as shown above!