RAK 1 Watt Case With CardKB and OLED

I originally wanted to find a case that would accommodate a CardKB and a 1.3 Inch OLED display, but I was unable to find something that had it all. So I decided to make my own.

Disclaimer: this device is very beefy. It's bigger and heavier than a phone, but for me, size wasn't a major design restriction, as I wanted something that could do everything, including functioning as a power bank.

This case can fit the RAK 1 Watt Booster Starter Kit, as well as a CardKB with the connector de-soldered, a 1.3 Inch OLED Display, a Waveshare Solar Controller (D), and a 12mm x 60mm x 110mm Battery (1260110 10,000mah 3.7v Li-ion).

RAK 1 WATT KIT

The kit used is the RAK 1 Watt booster starter kit that uses the 19007 base board. The kit has updated in the time I bought mine, as it now comes in two variants instead of one with jumper. Make sure to buy the EXTERNAL 5V POWERED VERSION! The battery powered version will not work if you follow me and use the Waveshare solar controller, as we are not connecting the battery directly to the RAK. The Waveshare regulates the power and sends a steady 5V 3A output to the RAK (enough to get the full 1 Watt output). But if you are skipping the solar controller all together and connecting the battery directly to the RAK, get the battery powered one.

Side note: if you use the 5V powered version like me, the battery percentage reading will be inaccurate, this is unavoidable for now, and only way to fix it is to use an INA219 sensor connected to the battery. However you can get an idea on charge when looking at the LEDs on the Waveshare controller board.

OLED DISPLAY

The OLED display is a 1.3 Inch screen using the SH1106 display driver. The pins need to be de-soldered to fit the case. The dimensions are in the photos attached, but if you're buying from AliExpress like I did for all the parts, I would be careful with putting the screen in, as it seems like there are many different screens sold with a slight variance in dimensions that don't match the schematic diagram (3D model may need to be modified slightly). The schematic for the OLED display is just the one from the listing that I bought it from.

SOLAR CONTROLLER

The Waveshare Solar Controller (D) has its solar input exposed at the bottom of the case, as well as charging LEDs and USB-C for charging the Li-ion battery. The battery is connected to the bat+ and bat- terminal block, and the RAK is connected to the 5V out terminal block, via a toggle switch. This also means that you can charge the battery with the toggle switch off, as the battery is charged via the Waveshare. I found that this device can also act as a power bank to charge your phone. I just had to turn off Fast-Charging in my phone settings for it to work.

CARDKB

The CardKB needs to have its connector de-soldered (Carefully!) to fit in the case. I ripped off a solder pad doing this, so be careful. 

The VCC, GND, SDA, and SCL wires have a grove to be routed from the CardKB to the bottom of the RAK 19007 board. The OLED screen is soldered to the same pins, but on the other side. I used 0.14mm² (26 AWG) wire to connect these.

BATTERY

The battery should fit in the grove nicely, I opted to get the 1260110, 10,000mah, 3.7V, Lithium-ion battery with a BMS, but its not really needed as the Waveshare has one built in. I just wanted to be safe. I have made groves for zip-ties to fasten the battery to the case, either one vertically, or two horizontally. The grove is made for the battery to go in upside down (Wires on the bottom) with the wires to the right when looking at the inside of the backing part.

THREADED HEAT INSERTS

All of the holes have been sized to fit brass threaded heat inserts. The threaded heat inserts used were M2.5 and M1.4 at varying lengths. You could probably get away with just the shortest length for both the M1.4 and M2.5, I just bought a kit with multiple lengths, so I wanted to use the longest I could for each hole, so I would be stronger. Only screws I used not included in the kit were the main case screws as they needed to be longer (M2.5 20mm long). Sizes I used are:

• 4 x main case holes: M2.5x6x3.5

• 4 (Only 3 needed) x RAK 19007 holes: M2.5x3x3.5

• 2 x RAK Booster holes: M2.5x4x3.5 (Can use the M2.5x3x3.5 instead)

• 4 x OLED holes: M2.5x2x3.5

• 4 x Waveshare holes: M2.5x2x3.5

• 2 x Switch holes: M2.5x2x3.5

• 4 x CardKB cover holes: M1.4x3x2.3

Make sure to pick the right screw length for the holes, because if the screws are too long, and you tighten them too far, they will pop out the back of the plastic on some parts where the holes are shallow. For example the Waveshare screws and the toggle switch screws.

OTHER

The case has a holder for a GPS module at the top, as well as two SMA connectors (I used 8cm long pigtails) for LORA and BLE.

The side has a slot for a toggle twitch (dimensions in the photos), that is meant to fit a switch with M2.5 screw holes. You may need to add a washer/spacer to be able to tighten the two screws properly to the case or else the screws could punch through the plastic to other side, as the shortest M2.5 screws that came with the kit were still too long. If you get a switch with a 4mm tall head, it will stick out only 1mm, meaning it won't be accidentally hit, but still easy enough to flick on and off.

Make sure to power the RAK with the 5V connector to the booster that comes with the kit, or else you will not get the full 1 watt output. I snipped the positive wire of the connector in the middle and connected it to the toggle switch to turn the RAK on and off.

FIRMWARE

I was unable to find Meshcore firmware that was supported by the RAK and that I liked the look of the UI, and that also supported the 1.3" OLED SH1106 display driver as well as the CardKB. So I decided to modify some firmware to support it. I really liked the look of the Mishmesh UI for the Wio Tracker, so I ported it over and made it work with the RAK as well as adding support for the SH1106 driver and the CardKB.

The firmware files can be found at the link below. Just drag and drop the .u2f file into the device when its in DFU mode (Double press reset button when plugged into computer via USB. It should show up as a device in file explorer): https://github.com/OSH1106/MeshCore-mishmesh

Link to the original Mishmesh firmware for the Wio Tracker is below. Eventually, I may add a pull request to merge my changes with the original author so that the RAK can be officially supported by the Mishmesh firmware:  https://github.com/burakcan/MeshCore-mishmesh 

PRINTING

I've only tested printing in PLA using a 0.4mm nozzle. I used Ironing on all top surfaces, but its only really necessary if you want a nicer finish. I'd recommend it on the buttons, as it makes them feel nicer to use. Make sure to add either modifier shapes with solid infill around the holes, or increase the wall/perimeter (to 5 maybe?), so that the heat inserts have enough plastic to grip onto when they get melted in place. 15% Gyroid infill is what I used and works great.

There are four 3D model files needed in the full build: the front of the case, the buttons, the CardKB back plate, and the back of the case. I have also uploaded the full assembly as a .step file, and the FreeCAD document file so you can easily change any part of the build if needed.

LINKS

I used 3D models of the CardKB and the Waveshare as a reference when creating the case. These files were created by other people that are linked here:

• CardKB by @Darkextratoas_243028: https://www.printables.com/model/793686-m5stack-cardkb-reference-model/files 

• Waveshare by Scott Willson: https://grabcad.com/library/waveshare-solar-power-manager-d-1 

PART LINKS

AliExpress links for exact parts I used (not sure how long these links will last, as they always seem to be deleting, but dimensions and images of parts used are attached in the photos, so you can find similar parts):

• RAK (External 5v): https://a.aliexpress.com/_mMZn9S7 

• OLED: https://a.aliexpress.com/_mr4aQUj 

• CardKB: https://a.aliexpress.com/_mqgwr4n 

• Waveshare: https://a.aliexpress.com/_mslMVIL 

• 1260110 Battery (With BMS): https://a.aliexpress.com/_mOl6NCf 

• SMA pigtails (8cm, SMA F): https://a.aliexpress.com/_mt9sweB 

• LORA antenna (SMA M): https://a.aliexpress.com/_mO1LnZp 

• BLE antenna (SMA M): https://a.aliexpress.com/_mNIEUjt 

• Switch (4mm tall head): https://a.aliexpress.com/_mrGHFlZ 

• Heat Inserts (M2.5 and M1.4/6 kit): https://a.aliexpress.com/_m0NqriL

• Case Screws (M2.5 x 20mm): https://a.aliexpress.com/_mrxOrOj 

Optional, but included in my build:

• RAK GPS (I used 12500, but it isn't listed anymore at the time of writing this. But the 12501 will work the same): https://a.aliexpress.com/_m0v08LZ 

• RAK BME680 Environment Sensor (RAK 1906): https://a.aliexpress.com/_mqZ8nfV