NFC trigger hard fault

[Roei]

Hi,

I have a problem of crash device after trying to connect my device to the PC via NFC. 

The issue is very rare.

I think that the issue occurs because of an assert in the function nrf_drv_clock_hfclk_release - ASSERT(m_clock_cb.hfclk_requests > 0).

How can I solve that?

In addition - I noticed that the functions in that file can be called form an interrupt context - isn't that unsafe to enter critical regions from an interrupt context? Maybe that can also cause some errors.

Thanks!

[Jared]

Hi,

I'm assuming that you're referring to this bug. It's scheduled to be fixed in a future release of the SDK. A workaround is also provided in the linked thread.

best regards

Jared 

[Roei]

Hi,

I think I already have this fix:

[Roei]

Is that the correct fix?

[Jared]

Not quite, the fix is the added if clause that checks if there is already a field on. The idea is to only release the clock if it has already been request earlier, avoiding decrementing the semaphore twice.  Workaround provided in the previous linked thread:

        case NRFX_NFC_FIELD_STATE_OFF:
            if (m_nfct_cb.field_on)     //This added if clause is the workaround
            {
                nrfx_nfct_state_force(NRFX_NFCT_STATE_SENSING);
#ifdef NRF52840_XXAA
                /* Begin: Bugfix for FTPAN-116 (IC-12886) */
                if (m_nrf52840.eng_a)
                {
                    *(volatile uint32_t *)0x40005010 = 1;
                }
                /* END: Bugfix for FTPAN-116 (IC-12886) */
#endif // NRF52840_XXAA
                nrf_nfct_int_disable(NRFX_NFCT_RX_INT_MASK | NRFX_NFCT_TX_INT_MASK);
                m_nfct_cb.field_on = false;
                nfct_evt.evt_id    = NRFX_NFCT_EVT_FIELD_LOST;
    
                NRFX_NFCT_CB_HANDLE(m_nfct_cb.config.cb, nfct_evt);
            }                       //The if statement ends here
            break;

[Roei]

OK,

It's different in my version, probably because I'm using a different SDK (for example - I don't have m_nfct_cb).

So I need to fix it like that:

Am I right?

[Jared]

Which SDK version are you using? Is the issue still reproducible?

[Roei]

I'm using SDK 15, and I saw that issue 

[Jared]

The fix is correctly implemented. Have you remembered to include it on both the t2t and t4t driver?  

[Roei]

The fix was implemented by me, it wasn't there before. And now it seems OK