Table of Contents

nRF52840 Notes

nRF52840 Notes

High Voltage Mode

Motivation

Simplify BoM and layout by using the nrf52840 VDDH → VDD LDO instead of an external 3.3 V LDO

Limitations

<25 mA output from VDDH to VDD (REG0)
2.5 V < VDDH < 5.5 V

Requirements

VDD must not be connected to VDDH or any power supply at reset
Adafruit nRF52 Bootloader → board.h → #define UICR_REGOUT0_VALUE UICR_REGOUT0_VOUT_3V3 (Adafruit nRF52 Bootloader GitHub search)
- If not defined, default REGOUT0 output = VDD = 1.8 V and GPIO output high = VDD = 1.8 V

Notes

nice_nano seems like a good bootloader variant to use if you need High Voltage mode

Further Reading

nrf52840 — POWER — Power supply

NFC Pins as GPIO

Motivation

Have more usable GPIO pins

Requirements

Adafruit nRF52 Bootloader → board.mk → USE_NFCT must not be = yes (Adafruit nRF52 Bootloader GitHub search)

Flash Bootloader with ST-Link

openocd -f interface/stlink.cfg -f target/nrf52.cfg -c "program nice_nano_bootloader-0.9.2_s140_6.1.1.hex verify reset exit"