What is it?

RFM110L is a low cost replacement of official kits from STM/Semtech, provided you have any 3.3V Arduino compatible boards at hand, such as FRDM-KL25Z/KL26Z/KL46Z/K20, NUCLEO-64/F103RB/F401RE/F072RB/L053R8. Just plug it into Arduino connector (3V3 only), download the firmware, you can kick off a LoRa/LoRaWAN project.

Why did you make it?

From the very beginning of my development of LoRa, I want to build a clone of the official development kits, because they were so expensive. And I need at least two of them to test point to point communications, and even more in stress testing in pilot deployment of a LoRaWAN gateway. After building that, I realized that I can share my spare boards or even build more boards to people who have same issues.

What makes it special?

RFM110L have following features:

• RF module compatibilities, we only use pin to pin compatible RF modules from different vendors.
• MCU compatibilities, thanks to Arduino/mbed/Freescale/NXP/STM, we can use many MCUs.
• Firmware compatibilities, thanks for ARM mbed/Arduino and Semtech, and we can use MDK/GCC to build.
• Design compatibilities, you can port official code including LoRaWAN/Aloha/PingPong/TXC/SCPI easily, just a few I/O and register adaption.
• SPI logic probes, allows people to probe the SPI bus, which is useful in board bring up.
• LP mode, reserved low power measurement pads.
• NVM pads, reserved for EEPROM/FeRAM via I2C bus and a power switch.
• 2 programmable LEDs.
• IPEX uFL/SMA connector, to connect antenna to gain more link budget.
• Easy to expand, including GPIO/ADC/PWM/I2C/SPI/UART/USB/CAN/Ethernet and WiFi/BLE/GPS/4G modules. Since Arduino/Nucleo/Freedom boards are designed for prototype development.

During my survey, I found official kits are ONLY for evaluation, which has a gap to a real project. Why we need dual band kit in one specific region? In EU, we need 868MHz, in US, we need 915MHz, in CN, we need 433MHz. Dual band application is rarely in the real projects.

So, using off-the-thelf RF modules, escpecially pin to pin compatible modules can help us to reduce the cost of inventory, reuse our designs and resources.

CAUTION

• The board only support 3.3V operation. Don't use 5V Arduino like Duemilnave and etc.
• The default product option is the shield board only, excludes any MCU boards. You can reuse your own boards at hand.
• The shield can be sold with a local NUCLEO Clone (F103RB or other micro) with additional cost.
• The local NUCLEO clone has no STLinkV2 on board, due to copyright issue.
• Limited firmware support, the developers are encouraged to port official code base from LoRaWAN. However I will offer an open source for RFM110L to demonstrate how to change the I/O layout for NUCLEO board.
• More design files, source code and documents are still in translation. We will speed it up to release some simple version first.

Deliverables

• Schematics (shield)
• Firmware (PingPong/LoRaWAN)
• Documentations (GetStarted)