Mini Ultra LoRaWAN

Description

Our first hurray into the LoRaWAN world! As with the tradition here at Rocket Scream, we do it with ultra low power fashion! We basically took our Mini Ultra 8 MHz board and mash it up with a LoRaWAN certified module. On top of that, we wanted to be able to power the board with a single cell battery such as 1.5 V AA or 3.0 V CR123A batteries. The Mini Ultra LoRaWAN works great with our beloved Arduino compatible low power library to allow flexible low power management of the board.  Read all about the design of the board here.

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 included and are sold separately (AA and CR123A).
• 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 and battery connector not included
• FR4 TG140 PCB with ENIG surface finish

Documentation:

• Design files on Github
• Schematic (pdf)
• Arduino compatible low power library on Github
• OTAA with TTN example sketch 
• Getting started guide (work in progress)