Modify Adafruit UF2 bootloader

[SaidAlvarado]

And use it to be able to flash ZMK to your keyboard via USB.

This project: https://github.com/adafruit/Adafruit_nRF52_Bootloader or ~this project: https://github.com/adafruit/tinyuf2~

• tinyuf2 is a bootloader for ESP and STM microcontroller, not for nRF

[SaidAlvarado]

By complete, it seems that my schematic is compatible with the port made for the nice!nano pcb

Here is the nice!nano port

In the pin definition file it request that

• P.018 be used for RESET with an internal Pullup. (I think, double check this in the nice!nano schematic, it would be a shame that it is a hardware pullup)
• P.019 be unconnected

/*------------------------------------------------------------------*/
/* BUTTON
 *------------------------------------------------------------------*/
#define BUTTONS_NUMBER    2  // none connected at all
#define BUTTON_1          _PINNUM(0, 18)  // unusable: RESET
#define BUTTON_2          _PINNUM(0, 19)  // no connection
#define BUTTON_PULL       NRF_GPIO_PIN_PULLUP

This matches my PCB, therefore I can most likely just use the binary precompiled for the nice!nano in the releases

[SaidAlvarado]

If I want the boot loader to have access the LED I need to change the pin file definition.

/*------------------------------------------------------------------*/
/* LED
 *------------------------------------------------------------------*/
#define LEDS_NUMBER       1
#define LED_PRIMARY_PIN   _PINNUM(0, 15) // Blue
#define LED_STATE_ON      1

Currently it's set to P0.15, this pin is disconnected. It would have to be changed to P0.02, that's the green LED on the board.