GPIO high during DFU

[Sergy]

Hello,

Id like to understand if its possible to held GPIO high during a DFU update? The usecase is as follows: 1)GSM module is usually controlled by NRF52832 and it also controls the power switch. 2)I will download a package and perform Serial DFU from GSM 3) I need to make sure that when switching to bootloader and after an update I dont get power pin low, otherwise it will shutdown GSM module.

The questions is how to make it work?

Thanks!

[Vidar Berg]

the gpio register is cleared on system reset, but you could try the approach we used in our legacy bootlaoder which was to branch to the reset handler of the bootloader instead of doing a system reset, see bootloader_util_reset() implementation in bootloader_util.c (included in SDK 11).

[jim-cat]

I solved a similar problem by making the following changes to my mcuboot image. This will keep the specified GPIO pin high while in bootloader/dfu mode. 

1. child_image/mcuboot.conf
   CONFIG_GPIO=y
   CONFIG_GPIO_HOGS=y
2. child_image/mcuboot.overlay
   &gpio0 {
       hog1 {
           gpio-hog;
           gpios = <24 GPIO_ACTIVE_HIGH>;
           output-high;
       };
   };

Reference:

github.com/.../36651