RAK833 LoRaWAN Concentrator

This board is a Raspberry PI Hat for the RAK833 LoRa Concentrator Gateway Module.

It is smaller version of the popular RAK831. The RAK831 is larger, about the same footprint than a Raspberry PI and requires a breakout board to convert the RAK831’s 24 pin connector to the Raspberry PI’s 40 pin connector. The RAK833 is a more elegant industry standard PCI Express Mini Card form factor (Type F2).

The RAK833 module consists of a Semtech SX1301 Digital Baseband chip for outdoor LoRaWAN Macro Gateways and two Semtech SX1257 Transceivers. The USB interface is provided by an FTDI FT2232H.

It supports both a USB and SPI interface selectable via the SPDT_SEL pin. This makes the module ideal for Raspberry PI and other Embedded Linux platforms that do no expose USB on the expansion connector.

Variants of the module are available for four different frequency ranges, 433MHz, 470MHz (China), 868MHz (Europe) & 915MHz (North America) and with or without the USB interface (FT2232H).

The RAK833-SPI/USB-xxx Mini PCie Module can be purchased from AliExpress for US$119. The non-USB version, the RAK833-SPI-xxx is US$99

Pinout

The following table provides details of the allocated I/O.

Pin No. PI Name PI I/O Type Net Name Function

8

GPIO14/TXD0 OUTPUT UART_TX GPS Receive (For configuration)

10

GPIO15/RXD0 INPUT UART_RX GPS Transmit

19

GPIO10/SPI_MOSI OUTPUT PCIe_MOSI SX1301 SPI Slave Input

21

GPIO09/SPI_MISO INPUT PCIe_MISO SX1301 SPI Slave Output

22

GPIO25 OUTPUT PCIe_RESET SX1301 Reset

23

GPIO11/SPI_SCK OUTPUT PCIe_SCK SX1301 SPI Clock

24

GPIO08/SPI_CE0_N OUTPUT PCIe_CSN SX1301 Chip Select

Software

Instructions for installing the software can be found at https://github.com/Lora-net/packet_forwarder/wiki/Use-with-Raspberry-Pi

The packet forwarder is configured via a global_conf.json file. Pre-prepared configuration files for different frequency plans/countries on The Things Network can be obtained from https://github.com/TheThingsNetwork/gateway-conf/

Design Files

Design files can be downloaded from the Circuit Maker website. Circuit Maker is a free EDA tool from Altium.

The PCB for this design was fabricated by JLCPCB.com. An earlier prototype was fabricated by pcbway.com.

8 Comments

  1. Jens,

    Yes, the PCB was designed in CircuitMaker and it requires designs to be made publicly available. Feel free to fork the design and modify it to suit your needs:
    https://circuitmaker.com/Projects/Details/Craig-Peacock-4/RAK833-LoRaWAN-Concentrator-Hat

    I have just added links on the above page to the Gerbers, Schematic and Bill of Materials for version 1.A.4. If you want to get boards make, you can submit these Gerbers to your preferred board house.

  2. Hi Craig,
    Nice work, thanks for sharing. I’m currently building one of your PiHat LoRa Gateway PCBs for use with the latest RAK2247 concentrator. I notice there’s a mis-match between the schematic and the BOM regarding R2 & R4 – the buck switch controller’s output voltage setting resistors. The BOM values seem to set an output voltage of 3.47V, whilst the schematic values are those of the Microchip reference design and set a voltage of 3.3V. Looks like you made a deliberate change here, I’d be very interested to hear your reasoning.
    Thanks again.
    Steve.

    • Steve,
      I’ve just cross referenced R2/R4 values with my prototype. The schematic is correct with R2 being 31.6K and R4 10K.
      I’m not sure what happened with the BOM, but these values are incorrect. Sorry for the confusion.
      Craig

  3. Thanks for your swift response and clarification. Couple of other quick questions if you’ll kindly indulge me: which GPS antenna do you use with the board? And do you have a feel for the average & peak total operating current on the 5V supply to Pi (2 or 3?), concentrator & GPS combined? I’ll let you know how I get on with the 2247.
    Thanks again,
    Steve.

  4. Thanks again Craig,
    I’ve now just got the 2247 working, through your board, with an RPi3B+ running from RAK’s disk image. FYI it draws 800mA of 5.1V current when used with an ethernet cable and with WiFi off, during boot the current peaks at about 1A. Had a small problem with the reset pulse to the 2247 – not sure if RAK’s software is driving the right pin – so I added a small script to pulse IO25 high then low at reboot which seems to make the system more reliable over power-cycles.
    I’m now considering a design for a super-cap based ups with enough energy storage to allow the Pi to shutdown cleanly prior to power-out – I’ve had quite a bit of trouble with trashed SD cards on RPis due to random power cuts.
    Thanks once more for sharing your excellent work, you’ve saved me many days of effort.
    Cheers, Steve.

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