{"id":2678,"date":"2024-11-16T18:31:59","date_gmt":"2024-11-16T17:31:59","guid":{"rendered":"https:\/\/www.nico-maas.de\/?p=2678"},"modified":"2024-11-16T19:02:35","modified_gmt":"2024-11-16T18:02:35","slug":"geeekpi-rpi-4g-hat-for-rakwireless-rak5146-usb","status":"publish","type":"post","link":"https:\/\/www.nico-maas.de\/?p=2678","title":{"rendered":"GeeekPi RPi 4G Hat for RAKwireless RAK5146 USB"},"content":{"rendered":"

In 2021 I started playing around with the SX1303 based RAKwirless RAK5146 USB LoRaWAN concentrator in mini-PCIe form factor ( 1<\/a>, 2<\/a> ). Back at the time I used the RAK2287 Pi Hat<\/a> which - even though the website states otherwise ("Note: RAK2287\/RAK5146 Pi HAT is compatible only with the SPI version of the RAK2287 and RAK5146 LPWAN concentrators.") is actually compatible with the USB version of RAK5146. In the second post I even want so far to hack the RAK2287 and bridge the PPS (Pulse Per Second) output of the included GPS onto the RPi GPIOs so that I could turn the RPi into a precise GPS NTP server - and I even added an I2C\/"poor-mans-QWIIC connector" to it.<\/p>\n

While all these hacks were successful and the balenaOS backed RPi 3 LoRaWAN concentrator was still working (with regular updates) in 2024, I finally wanted to streamline my overall IT setup: I had an WD My Cloud Mirror Gen2 NAS I updated to Debian 11<\/a> in 2022, the LoRaWAN concentrator\/NTP server<\/a>\/Room sensor RPi 3 and an very old Medion Laptop was I was abusing as the main "server" - it was time to unify those systems and move on.<\/p>\n

Luckily, I had gotten a TuringPi 2 and Turing RK1 SBCs which were a powerful combination: My plan was to use one RK1 in Node 3 position on the TuringPi 2 which did give the SBC one NVMe slot, a PCIe attached Dual Port SATA bridge and the additional USB 2.0 port which could be switched to any Node on the board. With the RK1 as a way more powerful CPU (in contrast to the old AMD 1 GHz Dual Core on the Medion Laptop...) and the Dual Port SATA bridge I already got Server and NAS functionality solved. But what about LoRaWAN and the other functionalities?<\/p>\n

Well, as I bought the RAK5146 USB (with LBT and GPS), I could just use the RAK2287 to plug a cable from the Micro USB cable into the additional USB 2.0 port of the TuringPi 2 - and this was done. However, what about the GPS and PPS input to allow for an NTP server? And did I really wanted to install the RAK2287 into an ugly box - or leave it open for further projects?<\/p>\n

Thats when I realized I still had the GeeekPi RPi 4G Hat at hand, an RPi "Hat" I bought back then when I thought that might be the cheaper alternative, but went out of my way to also buy the RAK2287 and never really tested it.<\/p>\n

The GeeekPi is just an ordinary hat, well - lets say it does not even has any connection to the RPi, just an USB C port - not even some GPIO connection - its basically just an "USB LTE Modem in mini-PCIe to USB breakout" in the shape of an RPi Hat.<\/p>\n

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Looking at the SIM Card Slot I had some mixed feelings and hoped that it would not interfere with the RAK5146 - so I rechecked the pinout<\/a>: <\/p>\n

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Luckily it turned out that the RAK engineers thought about this and marked the SIM Card Slot connectors as NC\/not connect. With this, this card could be inserted into any Laptops WWAN slot or an SBC like the balenaFin. Neat!<\/p>\n

After the pinout situation was clear, there was just one thing left: Soldering the needed connections directly to the mini-PCIe connector:<\/p>\n

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The needed pins were GND, PPS, PI_UART_TX and PI_UART_RX which I broke out onto a 2.54mm female header and fixed them into place with a bit of hotglue as strain relief:<\/p>\n

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Then I just needed to add an FTDI USB UART to the mix and connect these pins:<\/p>\n