LoRa32u4 An Alternative For Expensive Adafruit Feather M0 with RFM95 LoRa Radio.

Suddenly I got an idea of doing a project which neede LoRa and after done some googling I found an interesting board, Adafruit Feather LoRa32u4 RFM95. Awesome idea, ATmega32u4 and HopeRF RFM95 LoRa module on one PCB, Arduino compatible, reasonably small and light and also can be LiPo battery operated and has its own 1S LiPo charger. The only thing I did not like was the price tag: $34.95 is somehow slightly more than I’m willing to pay for ATmega32u4. Even with the radio module.

LoRa32u4

So, after some digging, I came across an awesome product that looks like a clone of Adafruit Feather LoRa32u4 RFM95. BSFrance LoRa32u4 II which cost only US $16.99

BSFrance LoRa32u4 II

LoRa32u4 II is a light and low consumption board based on the Atmega32u4 and HPD13 915MHz LoRA module and a USB battery charging circuit. Ideal for creating long-range wireless networks that can exceed 2.4 GHz 802.15.4 and similar, it is more flexible than Bluetooth LE. 

LoRa32u4
LoRa32u4

The ATmega32u4 is clocked at 8 MHz and 3.3 V. This chip has 32 K of flash, 2 K of RAM and built-in USB to Serial communication, debugging and programming capabilities without the need for an external FTDI chip, it can also act as an HID device (mouse, keyboard, USB MIDI device, etc). HPD13 wireless module, using high-performance, highly integrated RF transceiver chip SX1276 design.

Advanced LoRaTM spread spectrum communication technology to ensure that the module communication distance and anti-jamming capability greatly improved, and also achieved a very low current consumption.

Specifications

  • ATmega32u4 is running at 3.3V and 8MHz
  • All pins are 3.3V, 5V will fry the CPU
  • Onboard RF module is Semtech SX1276 based Shenzhen HPD13-868 (HopeRF RFM95W compatible)
  • There are both soldering pad and u.fl connector for antenna
  • RF module is connected via SPI bus plus:
    • SS pin: 8
    • RST pin: 4
    • DIO0 pin: 7
  • Board can be powered directly from 1S LiPo battery connected via JST connector
  • LoRa32u4 has build-in 1S LiPo charger. The charger works only when boards is powered from USB or 5V pin
  • There is no RAW input, that means it can operate only from 3.3V or 5V external power supply
  • Board can be used directly with Arduino when this board definition is installed. Just unzip it to Arduino/hardware the folder that it contains Arduino/hardware/bsfrance/avr
  • LoRa RF module can be programmed using Arduino LoRa library

Pin Out

LoRa32u4 RFM95 pinout

Connection of LoRa32u4 II and USBISP

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