Difference between bt_scan_start and bt_le_scan_start?

[cscase]

I'm working with the observer example, and in trying to make modifications to it I have looked at a couple of other projects, both online and from another product under development here, and in those projects I see bt_scan_start and bt_scan_init, etc. This is consistent with what I see in online documentation, too - for example, on this page:

developer.nordicsemi.com/.../scan.html

However, in the observer example, I see it uses bt_le_scan_start, and other references that all start with "bt_le_"

It seems like these two are not interchangeable and I've spent some time spinning my wheels experimenting and trying to figure out what works and what doesn't, but I think it's better if I just ask:

What is the difference between the two, and what factors should be considered when deciding which is better to use? It seems like the former is better documented online - or maybe I'm just looking in the wrong places?

Scott

[Hung Bui]

Hi Scott, 

If you have a look at \nrf\subsys\bluetooth\scan.c you can see the source code of ble_scan_start()

int bt_scan_start(enum bt_scan_type scan_type)
{
	switch (scan_type) {
	case BT_SCAN_TYPE_SCAN_ACTIVE:
		bt_scan.scan_param.type = BT_LE_SCAN_TYPE_ACTIVE;
		break;

	case BT_SCAN_TYPE_SCAN_PASSIVE:
		bt_scan.scan_param.type = BT_LE_SCAN_TYPE_PASSIVE;
		break;

	default:
		return -EINVAL;
	}

	/* Start the scanning. */
	int err = bt_le_scan_start(&bt_scan.scan_param, NULL);

	if (!err) {
		LOG_DBG("Scanning");
	}

	return err;
}

The \nrf\subsys\bluetooth\scan.c  is just an Nordic's abstract layer on top of the base scan.c in Zephyr's host layer inside. \zephyr\subsys\bluetooth\host . This is provided to simplify the API you need to call to do BLE. 

If you want you can use the bt_le_scan_start() directly and provide the scan parameters directly in the function. You can see that in Zephyr's sample they use the default bt_le API. 

There is no difference regarding BLE functionality between the two, it's just more simple to use the ble_scan_start abstract layer. If you want more advanced feature, for example scan callback , then you would need to use the bt_le_scan_start(). 

[cscase]

Thank you!