I'm finding that the MCUBoot stays stuck in bootloader mode sometimes when using a CONFIG_BOOT_SERIAL_DETECT_PORT.
I've narrowed it down to setting up the GPIO as input/pull-up and reading it being the next immediate operation - there are old posts outlining this could be an issue in nRF52 - i.e. can't read a pin immediately after it was pulled up and expect to get a high.
I'm using an nRF52840DK, PCA10056 v1.0.0 2018.17. Not sure if this is a silicon/DK issue or across the board with nRF52.
Using GPIO0 pin 12 (Button 2 on nRF52840dk)
/* The default presence value is 0 which would normally be
* active-low, but historically the raw value was checked so we'll
* use the raw interface.
*/
rc = gpio_pin_configure(detect_port, CONFIG_BOOT_SERIAL_DETECT_PIN,
#ifdef GPIO_INPUT
GPIO_INPUT | GPIO_PULL_UP
#else
GPIO_DIR_IN | GPIO_PUD_PULL_UP
#endif
);
__ASSERT(rc == 0, "Error of boot detect pin initialization.\n");
k_sleep(K_MSEC(10));
#ifdef GPIO_INPUT
rc = gpio_pin_get_raw(detect_port, CONFIG_BOOT_SERIAL_DETECT_PIN);
detect_value = rc;
BOOT_LOG_INF("det pin = %u rc = %u", CONFIG_BOOT_SERIAL_DETECT_PIN, detect_value);
The snippet above is from: ncs/bootloader/mcuboot/boot/zephyr/main.c
As you can see I added a k_sleep() betweeen the GPIO calls _configure() and _get_raw() and that seems to have eliminated the issue.
I'd appreciate if anyone else can confirm the issue or provide a better fix.
MCUBoot config file attached.
Thanks,
FJ
