Standalone device

Hi friends, I’m trying to build a standalone communication device using rak modules and a cardkb. I’m sure others here have built something similar before so I thought I should reach out since I’m unsure of a couple things (and certainly missed some others). Goals:

  • solar power with usb-rechargeable battery
  • keyboard for freetext input (cardkb since that’s all that’s supported atm)
  • e-ink screen
  • GPS
  • waterproof/dustproof enclosure

Things I don’t care about optimizing for this first iteration:

  • size
  • cost (within reason)

Context: I’m not very experienced with hardware, I’ve done some soldering but not a ton. Done a bunch of software and have a bunch of friends who tinker with hardware so I’m not concerned about learning or getting in-person help. My current plan is to use rak modules. Current BoM:

  • cardkb
  • RAK19001 (dual io base board) – or can I use a RAK19007 and if so do I need the RAK13002 io module?
  • RAK4631 (nRF52840 core module)
  • RAK14000 (epaper display)
  • RAK12500 (GPS module) – or do I need RAK1910? Is this dependent upon the base board decision?
  • battery – I have no idea how to select this, pls help
  • waveshare solar panel – the rak ones are sold out so I think this one might work but the specs are defined differently from the rak one so I don’t actually know which voltage to look at (Solar Panel (6V 5W), 156 monocrystalline cell)
  • If I can use the RAK19007, the unify enclosure solar (SKU:910315) – not sure this will fit the other pieces; otherwise, just gonna have to 3d print something (I’ll have to anyway for the cardkb and screen so nbd)
  • a LoRa antenna
  • do I need a ble antenna if I want to be able to connect it to a phone?
  • probably some cables, but which ones? also halp

That’s pretty much it, any help would be very appreciated!

1 Like

I would start here Printables


I’m a little late to the party but have some similar questions and maybe some helpful info if you haven’t successfully built this unit yet.

-I’m looking at the cardkb as well; Does it require an additional device to translate for the RAK device(s)?
-The RAK19001 allows for lots of extra sensors (if you’re building a weather station or something), the RAK19007 is probably what you need and I don’t think the RAK13002 is needed. The RAK19007 has a charging circuit built in, USB-C and Solar as well as a plug for a battery. Check all the specs here: RAK19007 WisBlock Base Board 2nd Gen Datasheet | RAKwireless Documentation Center
-RAK4631 supports bluetooth AND LoRa. Both will require an antenna (included in their starter kit SKU 116013 assorted options on core modules)
-RAK14000 looks pretty sweet… it has a 3 button board built in which could be used for canned messaging but I don’t know anything about that yet.
-Specs on RAK12500 and RAK1910 suggest that either will work with the RAK19007… might come down to power consumption, manufacturer, firmware compatability and/or some other specific features.
-Battery: The datasheet on the RAK19007 states Li-Ion or LiPo 3.7V~4.2V (these are sold as 3.7V but the peak voltage may be as high as 4.2, mAh are a measure of capacity and correlate directly to battery life). That being said each type has some pros and cons. I’ll be using a Li-Po for my standalone build and probably Li-ion for any remote/solar-only nodes in a LoRa system. I’ll be happy to share why if anyone wants the boring details.
-Solar panel: the charging system of the RAK19007 is rated for 5 volts. Your PV panel selection is 6(+/-5%) and may damage the charging circuit and/or require a transformer or some other additional equipment to safely use it. It is also around 9" if you were concerned about size. I bought these (not here yet but I’ll update with my experience) (BTW, RAKwireless has the appropriate plugs/wires to connect solar(JST ZHR-2 1.5mm) and battery ( JST PHR-2 2mm) to the RAK19007 directly)
-I’ll be making my own enclosure once I get all of the pieces together. 3D printers are amazing!
-LoRa antenna; I’ll update with my experience when I have some. I’ll be working with the antenna that comes with the starter kit at first but will likely end up using an adapter to go from IPEX to SMA and buy or build an antenna.
-BLE antenna will be required. DO NOT power on a radio without an antenna as it may suffer damage.
-Cables: other than your solar and battery leads you will need a USB-C for charging and/or interfacing for programming and possibly a cable for your cardkb if it does not come with one.

Hope that helps.

Bought all the things and tried soldering it together but it was too finicky for my skill level, especially the keyboard. Battery didn’t work either. I still wish the screen were eink. The rest of it was a functional device when plugged in but pretty useless for the whole “standalone” part and honestly even if it had worked the soldering took too long to really be worthwhile for me. If someone made a $100 pre-assembled device I’d buy it, but until that happens I’m not sure how much more time I’ll spend on this.

As for “another device” for the cardkb, the only things necessary were in the BoM of the printables project.