LoRaWAN 8-ch TTN gateway on a "Raspberry Zero W" !

Gerhard Peter

Initiator of "TTN Community Berlin"

Posted on 10-01-2018

Made by by Will Whang: Raspberry Pi Version: 99 USD, also Raspberry Pi Zero W (not commercial yet).

A Simple LoRa Gateway board using SX1308 and two SX1257

What is it?
This is a LoRa Concentrator/Gateway designed for Raspberry Pi, using SX1308 and two SX1257 @ 915Mhz band with MAX-7Q GPS module.

Why did you make it?
I started building LoRa gateway about a year ago because, in the early days, companies that made this didn't want to sell me only one unit. Also, I needed a little different setup(later description). Thus, trying to build my own version of the gateway.

What makes it special?
Well... If you don't know about LoRa Gateway, this board uses SX1308, which is a 8 frequency x 7~12SF @ 125Khz Bw LoRa + one Lora + one FSK channel decoder. Moreover, they can simultaneously decode, which means that even I have two nodes with different Spreading Factor but the same frequency and Spreading Factor, SX1308 still can decode both of them!

If you already know about LoRa - Gateways, this board is kind of a "stripped down version" of a normal gateway, because TX/RX is not combined together with an RF switch. On the dark-side, it means that you will have to use two antenna for RX/TX or adding your own RX/TX switch, but on the bright-side, you can tune RF like adding more powerful PA or lower noise LNA+Filter near antenna. Still, I've added a SAW Filter @ 915Mhz for RX, because SX125X doesn't have one onboard.

This board also comes with a MAX-7Q GPS module, and the pulse-per-second (PPS) output is connected both to SX1308 and to Raspberry Pi, so not only that SX1308 can have accurate timing, RPI also can be used it as a NTP server.

Also, because Raspberry Pi has two SPI hardware Chip-Select, I put a jumper on the bottom of the board, so you can select CE_0 or CE_1, and stack also two boards the same time, if you want to stack other boards, there's an option for "Extra Tall Header".

For TX/RX RF connector, you can choose U.FL or SMA. If you choose U.FL, it will come with two U.FL to SMA converters. Also, there is an optional GPS antenna, or you can connect to your own GPS antenna, as long as it is active Antenna.

The whole project is opensource. Files and WIKI are on GitHub. If you encounter any issue, please send an issue on the Github Page, also note that I might not able to provide strong support for this board, the SCH & PCB & software files are fully open, and this board is provided as is.
* https://github.com/will127534

* https://twitter.com/will_whang

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