Reset button doesn't work on some nRF52840 DK PCA10056 1.0.0 boards

[mtfurlan_t]

The reset button doesn't seem to work on two of my PCA10056 1.0.0 development kits, but works on two others, and works on some earlier versions.

I tested by running the peripheral/uart and peripheral/blinky examples with SDK 15.0.0 and SDK 15.2.0

nrfjprog -f NRF52 -r works fine.

What could I be doing wrong to make the reset button not work on two specific boards? I'm not modifying the examples to not define CONFIG_GPIO_AS_PINRESET or anything.

[AndreasF]

Hi.

Could you first measure if you have a signal on P0.18 when you click on RESET?

And then measure SB42 when you click on RESET?

You find SB42 close to DEBUG IN

- Andreas

[mtfurlan_t]

So on a board where the reset button does work, SB42 and P0.18 are around 3V unrelated to if I am pressing the reset button or not.

When the board is off, I can see connectivity between P0.18 and SB42, but not to any of the pads of the reset button.

I don't see a difference on boards that don't have a working reset button.

[AndreasF]

Hi.

1. Are the kits connected with USB? Make sure your kit is connected with USB. Could you measure using a oscilloscope that there is a pulse from P0.18 when you press reset? I had a 30ms pulse.

2. If there is no pulse, could you try modifying the following:

The function found in line 94 in nrf_drv_usbd_errata.h in location nRF5_SDK_15.0.0_a53641a\components\drivers_nrf\usbd

static inline bool nrf_drv_usbd_errata_type_52840_fp1(void)
{
    return ( nrf_drv_usbd_errata_type_52840() &&
               ( ((*(uint32_t *)0xF0000FE8) & 0xF0) == 0x10 ) &&
               ( ((*(uint32_t *)0xF0000FEC) & 0xF0) == 0x00 ) );
}

Try changing it to:

static inline bool nrf_drv_usbd_errata_type_52840_fp1(void)
{
    return ( nrf_drv_usbd_errata_type_52840() &&
               ( ((*(uint32_t *)0xF0000FE8) & 0xF0) == 0x20 ) && // note: modified from 0x10 to 0x20!
               ( ((*(uint32_t *)0xF0000FEC) & 0xF0) == 0x00 ) );
}

There could be that this small bug in the SDK is causing your issue.

- Andreas

[mtfurlan_t]

I do see a 30ms drop to ground on pin 18.

[AndreasF]

Hi.

Then there shouldn't be anything wrong with the hardware. Can you try to modify what I wrote in my last reply?

- Andreas