CAF: Latch register for all button GPIOS are set when wakeup from deep sleep by single button press, making it impossible to know which button that did the wakeup

[tellg]

I used the Common Application Framework preview sample, with the following additions at end of prj.conf:

# Power management
CONFIG_PM_POLICY_APP=y
CONFIG_CAF_POWER_MANAGER=y
CONFIG_CAF_POWER_MANAGER_TIMEOUT=10
CONFIG_CAF_BUTTONS_PM_EVENTS=y
CONFIG_CAF_LEDS_PM_EVENTS=y

NCS 1.9.1 was used

The nrf52840dk then enters deep sleep after 10 seconds.

When I then perform a button wakeup, by clicking one of the DK buttons, then the GPIO LATCH bits for all 4 buttons are set.

I would expect that only the LATCH bit is set corresponding to the button that was pressed.

Since the LATCH bit is set for all four buttons, this makes it impossible to see the cause of wakeup.

Could this be a bug in the CAF Buttons module?

BTW: This issue was discovered when looking at the case in devzone.nordicsemi.com/.../how-to-detect-gpio-interrupt-source-from-deep-sleep , but using CAF and ncs instead

[tellg]

Seems to be a problem only when debugger is active.

But to get the real button wakeup source, the latch can be read and cleared in

PRE_KERNEL_1 hook before main() as shown in attached modified main.c

Fullscreen 773083.main.c Download

/*
 * Copyright (c) 2021 Nordic Semiconductor ASA
 *
 * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
 */
#include <event_manager.h>
#include <device.h>

#define MODULE main
#include <caf/events/module_state_event.h>

#include <logging/log.h>
LOG_MODULE_REGISTER(MODULE);

static volatile uint32_t g_wakeup_latch;
static volatile uint32_t g_wakeup_latch_after_clear;

static int detect_wakeup_latch(const struct device *dev)
{
	ARG_UNUSED(dev);

	g_wakeup_latch = NRF_P0->LATCH;
	// Reconfigure the button pins to reset condition before trying to clear the latch
	NRF_P0->PIN_CNF[11] = 0x00000002;
	NRF_P0->PIN_CNF[12] = 0x00000002;
	NRF_P0->PIN_CNF[24] = 0x00000002;
	NRF_P0->PIN_CNF[25] = 0x00000002;
	NRF_P0->LATCH = NRF_P0->LATCH; // clear the latch
	
	// 3 dummy reads (needed according to errata)
	(void)NRF_P0->LATCH;
	(void)NRF_P0->LATCH;
	(void)NRF_P0->LATCH;

	g_wakeup_latch_after_clear = NRF_P0->LATCH;

	return 0;
}

SYS_INIT(detect_wakeup_latch, PRE_KERNEL_1, 0);

void main(void)
{
	LOG_INF("NRF_P0->LATCH, at wakeup = 0x%08x, after clear = 0x%08x", g_wakeup_latch, g_wakeup_latch_after_clear);

	if (event_manager_init()) {
		LOG_ERR("Event manager not initialized");
	} else {
		module_set_state(MODULE_STATE_READY);
	}
}

Please note that the original issue is still present if running with debugger.

[Priyanka]

Hi,

What is your J-Link version?

-Priyanka

[tellg]

7.60c

It also seems like after running with debugger, I have to flash again (using flash button) to get it to work again

[Priyanka]

Hi,

I am not able to reproduce the problem at my end so far. I have a few questions though.

In the screenshot that you shared, it looks like you are trying the default main file for caf and not the one that you have shared here in the ticket.

Also, when you say that you are not able to latch separately when using a debugger, do you mean that when you start the debug session, you get this error? or only when you connect an external debugger this problem arises?

Could you share a zip file of your entire project folder so that I can try to reproduce it here?

Regards

Priyanka

[tellg]

Yes the screenshot was for before the one I shared.

The problem is still there if I start a debug session instead of just flashing the nRF52840dk board

I used the built-in debugger on the board, not an external J-Link

Board label is: PCA10056, 2.0.2, 2021.43, 683783911

0576.caf.zip

[Priyanka]

Unfortunately the CAF button module does not allow to mention which key should be used for wake up etc. So if you want have a wakeup using only one of the DK buttons, you could try to go back to sleep if all other buttons are pressed.

-Priyanka