Microcontroller projects

LoRa key running on a single coin cell

last updated: 2024-02-26

more coming soon :)


lora key

Burning the bootloader and programming the chip

Everything is explained in the tips and tricks section.

Burning the bootloader

Name Arduino Uno ISP Arduino Uno Header ATmega328PB (TQFP_32)
MOSI 4 11 15
MISO 1 12 16
SCK 3 13 17
Reset (CS) 5 10 29
3V (5V) 2 3V3 (5V) 4

As I had problems by using the ISP header (wrong chip signature) I would recommend to use the normal header!

lora key burn bootloader            lora key burn bootloader

lora key burn bootloader

Programming with Arduino

USB to Serial cable (FTDI) ATmega328PB (TQFP_32)
RTS (green) 29 (Reset)
RxD (yellow) 31 (TxD)
TxD (orange) 30 (RxD)
3V (5V) 3V Battery +
GND 3V Battery -

lora key program it            lora key program it



lora key top      lora key bottom

lora_key circuit

To stabilise the ADC readings a second capacitor of 100nF should be soldered in parallel to R2 (C2 = 100nF // to R2)