USB disconnect causing system reset

[donbosley]

Software : C / GCC - SDK 15.0.0 - SD140 6.0.0 - building on multiple platforms. 
Hardware : nRF52840-DK (Q1AAC0) - and secondary testing on custom board using the Fanstel BT840 Module 

Whenever the chip is in low-power, and the USB is disconnected there is a system reset.

We're using POWERMANAGE_... for sysoff, wakeup
And in the case of including an event handler it's the 


1) No USB device, no USB handlers or events included. Enter low power via button push, plug in USB, unplug results in full system reset. 
2) USB Event Handler included : nrf_drv_power_usbevt_init() --> linked to custom power_usb_event_handler(nrf_drv_power_evt_t event)
-- but no other service (no ACM, MSD, etc...) 
-- Plug in USB (reaches NRF_DRV_POWER_EVT_DETECTED) puts device into sleep
-- Unplug never hits USB event handler NRF_DRV_POWER_USB_EVT_REMOVED

So no USB handler set up, reset, USB handler set up - reset. Happens on both boards.

Is there some flag deep in the sdk we need to unset in order to tell the chip not to reset on unplug or are we looking at something in hardware? 

[Kenneth]

Hello, can this be the case: https://infocenter.nordicsemi.com/topic/errata_nRF52840_Rev1/ERR/nRF52840/Rev1/latest/anomaly_840_197.html?cp=4_0_1_2_1_29 

Also please update to SDKv15.2 for various bug fixes.

[Mihal]

hi. looks like i have a similar problem on SDKv15.2 

NRF_DRV_POWER_EVT_DETECTED is presented and i can process it BUT only when firmware is active. 

my code is super simple. 

switch (event)
{
case NRF_DRV_POWER_USB_EVT_DETECTED:
    NRF_LOG_INFO("USB power detected");
    if (!nrf_drv_usbd_is_enabled()) {
        if ( !POWER_ON() ) sleep_mode_enter();
    }
    break;
case NRF_DRV_POWER_USB_EVT_REMOVED:
    NRF_LOG_INFO("USB power removed");
    if (!nrf_drv_usbd_is_enabled()) {
    if ( true ) sleep_mode_enter();
    }
break;
default:
}

it supposed to check whether program have been already running before the event.

NRF_DRV_POWER_USB_EVT_DETECTED works perfect

but NRF_DRV_POWER_USB_EVT_REMOVED can not be processed from sys_off even if there is always true as i put in example

UPD: your link in a comment above is broken