Rocketscream presents a new Arduino ultra low power node

Gerhard Peter

Initiator of TTN Berlin

Posted on 02-08-2018

http://www.rocketscream.com/blog/2018/06/18/single-cell-arduino-compatible-lorawan-low-power-node/

Specifications:

  • Compatible with Arduino IDE using “Arduino Pro or Pro Mini (ATMega328 3.3V 8 MHz)” as the board option
  • Microcontroller – ATMega328P-AU
  • Clock – 8 MHz crystal
  • Operating voltage – 3.3 V
  • Ultra low power:
  • Minimum 35.0 μA in sleep mode with a fresh 3.0 V Lithium CR123A battery
  • Minimum 70.0 μA in sleep mode with a fresh 1.5 V AA battery
  • Battery voltage can be as low as 1.1V (with alkaline based AA batteries, performance varies with various battery chemistry, brand, temperature and other factors)
  • Battery connector options – AA or CR123A battery holder but battery power can also be supplied through the breakout pins (single or dual 1.5 V batteries of any size can be used):
  • Battery connector are not mounted by default even if included
  • RN2483A/RN2903A can be used as a wake up source while the ATMega328P is in sleep mode
  • All pins of RN2483A/RN2903A are made available on the breakout pins:
  • Up to 14 digital IO pins can be used as input or output
  • Battery monitoring on pin A6
  • Ultra long range LoRaWAN radio module options:
  • Microchip RN2483A – 868 MHz (433 MHz port are made available with u.FL connector)
  • Microchip RN2903A – 915 MHz
  • 2 options of antenna connector:
  • SMA
  • u.FL (u.FL connector is also assembled on 433 MHz port on the RN2483A version)
  • Reverse battery protection
  • Automatic power switch over from battery to external 3.3 V power supplied on the FTDI 6-pin header
  • Indicator LED connected to digital pin 13 through a MOSFET
  • ATMega328P communicates with RN2483A/RN2903A over UART through pin D8 & D9 using AltSoftSerial written by Paul Stoffregen (vs the Arduino IDE stocked SoftSerial library)
  • Side reset tact switch for easy access (for both ATMega328P and RN2483A/RN2903A)
  • Slide switch to isolate the RN2483A/RN2903A UART pins from the ATMega328P’s pins during RN2483A/RN2903A firmware upgrades
  • FTDI USB serial 6-pin header for code upload
  • Works below sub-zero temperature
  • Footprint for optional encryption chip ATECC508A/ATSHA204A from Microchip that runs on the I2C bus (also fits many other memory devices that works on I2C bus)
  • 900 mil in between 2 breakout headers – suitable for breadboard usage
  • Dimension – 25.4 mm x 77.47 mm (1.0″ x 3.05″) (without the SMA connector)
  • RoHS compliant – Yes
  • Antenna not included
  • FR4 TG140 PCB with ENIG surface finish

Documentation:

Design files on Github
Schematic (pdf)
Arduino compatible low power library on Github
Getting started guide