samples: 802154_sniffer: add bootloader command.

Add `bootloader` command that allows nRF52840 dongle to reboot
into bootloader by pulling the P0.19 GPIO pim connected to reset
to GND.

This allows easy reflashing of the dongle without physical access
to the device.

Signed-off-by: Maciej Baczmanski <[email protected]>

Author: maciejbaczmanski

samples/peripheral/802154_sniffer/README.rst

@@ -90,6 +90,21 @@ The ``sleep`` command disables the radio and ends the receive process.
 
       sleep
 
+bootloader - reboot the device to the bootloader
+================================================
+
+The ``bootloader`` command reboots the device in bootloader mode.
+
+   .. parsed-literal::
+      :class: highlight
+
+      bootloader
+
+The device reboots into bootloader mode, and the red LED starts pulsing.
+
+.. note::
+   The ``bootloader`` command is available only for the ``nrf52840dongle/nrf52840`` board.
+
 Configuration
 *************
 

samples/peripheral/802154_sniffer/src/main.c

@@ -14,6 +14,11 @@
 #include <stdlib.h>
 #include <dk_buttons_and_leds.h>
 
+#if defined(CONFIG_BOARD_NRF52840DONGLE)
+#include <zephyr/drivers/gpio.h>
+static const struct device *const gpio_dev = DEVICE_DT_GET(DT_NODELABEL(gpio0));
+#endif
+
 #define HEX_STRING_LENGTH (2 * MAX_PACKET_SIZE + 1)
 
 static const struct device *radio_dev =
@@ -128,6 +133,34 @@ static int cmd_sleep(const struct shell *shell, size_t argc, char **argv)
 }
 SHELL_CMD_ARG_REGISTER(sleep, NULL, "Disable the radio", cmd_sleep, 1, 0);
 
+#if defined(CONFIG_BOARD_NRF52840DONGLE)
+static int cmd_bootloader(const struct shell *shell, size_t argc, char **argv)
+{
+	/*
+	 * nRF52840 dongle has pin P0.19 connected to reset. By setting it
+	 * in `GPIO_OUTPUT_LOW` mode, reset is pulled to GND,
+	 * which results in device rebooting without skipping the bootloader.
+	 */
+	ARG_UNUSED(shell);
+	ARG_UNUSED(argc);
+	ARG_UNUSED(argv);
+
+	if (!device_is_ready(gpio_dev)) {
+		shell_print(shell, "GPIO device not ready");
+		return 0;
+	}
+
+	int err = gpio_pin_configure(gpio_dev, 19, GPIO_OUTPUT_LOW);
+
+	if (err) {
+		shell_print(shell, "Failed to configure GPIO pin. Error code: %d", err);
+	}
+
+	return 0;
+}
+SHELL_CMD_ARG_REGISTER(bootloader, NULL, "Reboot into bootloader", cmd_bootloader, 1, 0);
+#endif /* CONFIG_BOARD_NRF52840DONGLE */
+
 int main(void)
 {
 	(void) dk_leds_init();