Enter bootloader from app on stock nRF52840 dongle

Question

Hi, 
 using a stock nRF52840 dongle and willing to enter bootloader (same as pushing the relevant button on the dongle) from app. How can that be done, using stock bootloader? 
 Regards, 
 Andrea

bjorn-spockeli · Accepted Answer

Hi Andrea, 
 it turns out that you were correct, the bootloader used on the nRF52840 dongle does not have the NRF_BL_DFU_ENTER_METHOD_GPREGRET. It only enables NRF_BL_DFU_ENTER_METHOD_PINRESET and NRF_BL_DFU_ENTER_METHOD_BUTTON_PIN. 
 I knew that we are able to switch from application to bootloader without manually pressing the button on the nRF52840 when programming it with nRF Connect: Programmer. So I took a look at the schematic file(attached) of the nRF52840 dongle and saw that several GPIOs were connected directly to the RESET pin, which is how nRF Connect is able to switch from app to bootloader. We have a dedicated USB library for this, called the DFU Trigger Library (USB) . 
 So I do not know how you want to trigger the nRF52840 to go to bootloader moder, but in essence you only have to pull on of the GPIOs connected to the RESET pin low, i.e. 
 
#define BSP_SELF_PINRESET_PIN NRF_GPIO_PIN_MAP(0,19)

// Call the following functions at the start of main()
nrf_gpio_cfg_output(BSP_SELF_PINRESET_PIN);
nrf_gpio_pin_set(BSP_SELF_PINRESET_PIN);

// Call the following function when you want to switch to BL mode. 
nrf_gpio_pin_clear(BSP_SELF_PINRESET_PIN); 
 I have verified this on a nRF52840 Dongle with the factory bootloader. 
 PCA10059_Schematic_And_PCB.pdf

Enter bootloader from app on stock nRF52840 dongle

Top Replies