We identified an issue affecting some Litl v2 PCBs. Read on to see if your PCB is affected and how to address the identified issue.
Is my PCB affected?
- Litl v2 PCBs that have the option of a key switch on the rotary encoder positions are affected.
- Litl v2 PCBs that have no additional holes for rotary encoders are not affected.
- Litl v1 PCBs are not affected.
See photos below to identify your PCB
If you have an unaffected PCB, then no need to do anything else! Your Litl PCB should be working great.
How are the PCBs affected?
In the affected Litl v2 PCBs, one of the switch solder pads on the leftmost rotary encoder is shorted with the GND net. This will mean that any press of a key in the 2 right hand columns (rotary encoder presses, backspace, P, enter, split enter, period/. and right shift) will trigger other keys in the same row. This was an issue introduced when we added the alternative to have a switch or rotary encoders in the top right positions.
How to fix the issue
In order to fix the issue you will have to make a small cut of a trace on the back of the PCB.
This cut will isolate the top pad on the leftmost rotary encoder (when viewed from the front) and prevent any further issues from occurring. You are able to make this cut even if you have started soldering the board.
If you are using a Litl configuration with 1 OLED and 1 rotary encoder you will need to make this cut. If you are using a Litl configuration with 2 rotary encoders you will need to make this cut.
If you plan on using a key switch in the leftmost rotary encoder position, then this fix will not work for you and you will need a replacement PCB. We have reached out to all affected parties but if you believe you have an issue, please get in touch at hej@sthlmkb.com
See the image below for where to make the cut of the trace on the back of the PCB.
To make the cut you need to sever the small line running vertically between the two holes show above. It does not need to be a long cut, just enough to sever the small raised section between these two holes. We used a sharp kitchen knife to make the cut, but a box cutter or scalpel blade may work equally well.
How will I know that it has worked?
You will know that cut has worked if you use a multimeter to see if those two holes are not connected anymore (i.e. you will see infinite resistance on a multimeter). You can further verify this by checking to see if there is a connection between the lower hole and any ground pad on the board (e.g. the square OLED pad). If there is no connection after making the cut, then you have been successful.
Now when you test your keyboard after having flashed and installed the microcontroller you should not see multiple keys triggered when you press a single key.
We have reached out to all those customers who we believe have an affected board. We apologise for any challenges that this might have caused during your keyboard build.
If you have any questions about the fix or anything else, please get in touch at hej@sthlmkb.com