BLE Disconnect error from within timers timeout callback function

[Stjepan Brlecic]

Hi,

I have a question regarding the nRF5340 Development Kit.

I use nRF5340 in the BLE Central role, I'm using a similar code like in the example central_bus.

Sometimes service discovery "bt_gatt_dm_start" takes too long.

To resolve that I start the timer before calling discovery (k_timer_start before bt_gatt_dm_start) so that way if it takes too long I want to disconnect from BLE peripheral, but I get an error when trying to disconnect from within timer_timeout__func.

The error that I get is

ASSERTION FAIL @ WEST_TOPDIR/zephyr/kernel/sem.c:121
E: r0/a1: 0x00000004 r1/a2: 0x00000079 r2/a3: 0x00000001
E: r3/a4: 0x0000372d r12/ip: 0x00001000 r14/lr: 0x000120b7
E: xpsr: 0x41000025
E: Faulting instruction address (r15/pc): 0x00015388
E: >>> ZEPHYR FATAL ERROR 4: Kernel panic on CPU 0
E: Fault during interrupt handling

E: Current thread: 0x20000fa0 (unknown)
E: Resetting system

Can someone help, how to disconnect from within timeout callback?

[Edvin]

Hello,

You can't call the disconnect function from a k_config timer interrupt. The correct way to do this is described in the "Timers" documentation from the zephyr project:

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/reference/kernel/timing/timers.html#using-a-timer-expiry-function

Look at how it defines K_WORK, and a k_work_handler. From there you can disconnect your connection:

void my_work_handler(struct k_work *work)
{
	int err = 0;
	LOG_INF("my_work_handler:);
	if (default_conn != NULL) {
		err = bt_conn_disconnect(default_conn, BT_HCI_ERR_REMOTE_USER_TERM_CONN);
		LOG_INF("disconnect err = %d", err);
	}
}

void my_expiry_function(struct k_timer *timer)
{
	LOG_INF("Timer expired.");
	k_work_submit(&my_work);
}

At least I tested your approach, and got a similar assertion, but this implementation worked without any issues.

Best regards,

Edvin