dongle hardware

[Sama]

Hi,

I have several questions about the dongle board.

1. Why should the p0.19,20,..,25 be connected to the reset pin?

2. what is the difference between the reset button and disconnecting the power to enter the DFU mode?

I have downloaded the open bootloader code on the nrf52840 devkit. Then I have programmed the board with a blinky example. Once I switch off and then on the board, it enter the DFU mode, unlike the dongle running the app. Why?

3. If I want to power up the dongle with an external power through the vdd-nrf I should remove the SB2 and connect the SB1.

3.a. In this situation, can I program the dongle by using the USB port yet?

3.b. If I erased that through the link, how can I back to the DFU by using a USB port?

[Bendik Heiskel]

Hi Sama.

 

1. Why should the p0.19,20,..,25 be connected to the reset pin?

 The reset pin is connected to the inner row of GPIO pins to be able to route it out from under the chip without using micro vias.

2. what is the difference between the reset button and disconnecting the power to enter the DFU mode?

The reset pin is one of the possible ways to enter DFU mode, disconnecting power does not enter DFU mode. For more information on entering DFU mode see https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.0.2/lib_bootloader.html?cp=8_1_3_5_0_2#lib_bootloader_dfu_mode.

 

I have downloaded the open bootloader code on the nrf52840 devkit. Then I have programmed the board with a blinky example. Once I switch off and then on the board, it enter the DFU mode, unlike the dongle running the app. Why?

The reset button on the nRF52840 development kit is connected to a signal switch which is connected to the nRF52840 and the IF MCU on the board. By changing the config of the open bootloader example to use one of the GPIO pins connected to the buttons on the DK to enter DFU mode instead of the reset pin, the bootloader works as expected.

3. If I want to power up the dongle with an external power through the vdd-nrf I should remove the SB2 and connect the SB1.

 Yes, SB2 must be cut and SB1 shorted. Keep in mind that SB1 and SB2 must not be connected at the same time, as this will damage the chip.

3.a. In this situation, can I program the dongle by using the USB port yet?

 Yes it should be possible.

3.b. If I erased that through the link, how can I back to the DFU by using a USB port?

 If the bootloader of the dongle is deleted, a programmer/debugger connected to SWDIO and SWDCLK must be used to flash a bootloader with DFU over USB support to the dongle.

Best regards,

Bendik Heiskel