UART DFU for nRF52833

[rcerati]

HW setup is my boart connected to a windows10 PC with an uart link.

I tried secure_bootloader_pca10100_uart_ses_nRF5SDKThreadv4.1.0.zip example, with some modification for my board, es UART pins in custom_board.h

#define RX_PIN_NUMBER 7
#define TX_PIN_NUMBER 6
//#define TX_PIN_NUMBER 35
#define CTS_PIN_NUMBER 8
#define RTS_PIN_NUMBER 40
#define HWFC true

To validate uart pins changes I tested the uart example in examples\peripheral\uart\pca10100\blank\ses and it works fine both without HW flow control and with HW flow control.

When I send 

nrfutil dfu serial -pkg blinky_pca10100_mbr.zip -p COM5 -b 115200

it seems all freezed: RTS signal from PC goes low, but nRF52833 RTS pin remains high. If I force low that signal PC starts transmitting.

A second question

The DFU example uses (in sdk_config.h) Button for entering DFU mode and set NRF_BL_DFU_ENTER_METHOD_BUTTON_PIN to 25: in my board I cannot access to that pin and I want to use PIN0.2.

I set in custom_board.h

#define BUTTON_4       2

and in sdk_config.h

#define NRF_BL_DFU_ENTER_METHOD_PINRESET 1

I add Enter DFU mode on pin reset

Is it correct ?

How can I debug the DFU example ?

Best Regards

[rcerati]

Now  interface chip works !

With PCA10100 board connected to PC with a usb cable on j2 connector, I programmed fw with MSD functionality, then I tried to use virtual com with nrfutil but it didn't work.

All changes if I program the board with 

nrfjprog -f NRF52 --sectorerase --program NORDIK_SDK_v4\examples\dfu\secure_bootloader\pca10100_uart\ses\Output\Release\Exe\secure_bootloader_uart_mbr_pca10100.hex --reset

Now nrfutil is able to program the chip

nrfutil dfu serial -pkg blinky_pca10100_mbr.zip -p COM6 -b 115200

  [####################################]  100%

Device programmed.

I want to perform another test with the PCA10100 board:

move nRF52833 UART on other pins, using pins P1.01/02/03/04, and connect the UART to the PC with an external USB-UART serial bridge.

[Vidar Berg]

Glad to hear that it works. It should be sufficient to to change the UART pinout in the bootloader FW to support the external serial bridge.