Hi all,
I have an idea in my head, but I’m a cable short, and looking for suggestions.
24-key split-ortho (2 keys per finger, where you press both top and bottom keys simultaneously to get the home row key), with per-key RGB and OLED display on the left side. But…
I’d like to run this off a single BlackPill controller on the left hand side, and use a CAT6 cable to bridge the two sides.
CAT6 has 4 twisted pairs, so 8 cables. If I run a 4x3 matrix then that’s 7 cables. Plus another for the VCC for the RGB. But then no more for the DIN/DOUT for RGB. GND should be fine as I can earth the right hand side separately, but I’m missing a cable if I want RGB.
Are there any suggestions on how I might be able to get around my challenge?
I’m not too familiar, but I’ve been told shift registers or IO expanders can save pins. In my small amount of research, it seems like they work (both of them seem to do the same thing? I’m honestly not sure what the difference is) by converting parallel signals to serial signals like SPI or I2C. For example, with I2C (the one that requires fewer wires), I think you could wire up your 4 columns… to the 4 wires of the I2C standard, which are VCC, ground, and two data lines, but if you’re able to use those same lines for ground and VCC for the rest of your board too, you’d be effectively saving two wires. Note1: If they share VCC cable with the RGB’s you’d have no ability to cut the external power, but maybe for a wired board you don’t care about that. Note2: Not sure if you could wire all 7 matrix wires to one expander… for me at least that wasn’t an option because to not have to do constant polling, you can only use an expander on the output side of the matrix. Avoiding constant polling is a power concern when building a wireless board.