Design Tradeoffs

If there's one thing I've learned over the years, it's that any project is about tradeoffs. Optimize one variable and a different one might suffer. With Gergo this point has been hammered into my head fairly hard. But I hope this document shows the various considerations I've taken into account here.

Cost. is the main factor many designs boil down to and Gergo aims to be a accessible keyboard first, and everything else second. To accomplish this SMD packages are used, keys were scrapped and the PCB footprint reduced. Each of these actions allows savings on the total cost to be passed down and works to minimize production costs. A caseless board can be put together with PBT caps off Aliexpress and Gateron switches for under 100$!

Accessibility. Keyboards are hard and the community fairly large, by offering assembly services users unfamiliar with PCB work can receive a mostly assembled keyboard with accessible through hole switches. Failing that, I'll build and test a board for the right price.

Size. As Gergo is meant to be portable and caseless, size consideration played largely in changing the overall footprint of the device. To fit in a bag well, the device can't have a large footprint so some sacrifices must be made. The number row was the first to go followed by the hard to reach 1u keys on the paddle, that reduced the board size, but still leaves it functional. Here I needed to be careful though, for every key you remove the user begins to rely more heavily on layers and special toggles.

Height. Coming from the ErgoDox one of the first things I noticed was how tall the entire unit is. With a case the ErgoDox is unusable for any length of time without a dedicated wrist rest, fine and dandy for at home but another item to the bag when out and about. To combat this instead of a case rubber standoffs are attached to rise the board and prevent scraping on a desk. This action alone reduces the overall height by almost a whole centimeter! This comes at a cost to aesthetics however and the silkscreen has been designed with exposed PCB in mind.

Extensibility. For a time I toyed around with replacing the Atmega32u4 with another micro to reduce cost. The problem with that is then you lose compatibility with the wonderful QMK software. For Gergo I opted to stay on the AVR platform as many makers are familar and can lend a hand with projects (Be it at a HackerSpace or online). But seeing as flashing firmware is part of the reality of DIY keyboards, it's safe to assume a technical crowd. This is why I've included pads for the ICSP and unused pins, if you choose you can integrate a little OLED display or some other external device by soldering on a few wires! Or if you botch your bootloader, force a flash using a usbASP or similar device.

Components, SMD wasn't really a choice here due to size. To keep costs down and improve durability through hole components were not a viable option. If there were SMD Cherry switches I'd probably have used those as well. The pads are all hand solderable because I'm not a sadomasochist. If you've never tried soldering these guys you'll know how to work with them by the end of your build!

Repairability. SMD is tough, and if you don't believe my try ripping off a 0805 with your hands. By having all the pads exposed swapping switches or replacing/touching up connections is less of a chore and more of something to do with a coffee on the desk. The less time I need to spend handy with a screwdriver the better!

This project has given me much to think about in regards to future designs. If there is anything you'd like to suggest please reach out to me!

2 comments:

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