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Jorge’s Status Report for Feb. 12

  • Jorge’s Status Report for 2/12/22

I started by designing some preliminary layouts for our keyboard which is designed for right handed use for now, but can be easily flipped if necessary. I based it off of existing layouts but with a goal to make a much simpler to use and intuitive layout. Besides the design of the keyboard button layout we also looked at the components we will be using. Standard mechanical keyboard switches work well and can be laid out in Eagle relatively easily.  We decided on linear key switches because they are the most comfortable to use and Carlos will be designing some custom keycaps for them that will be slightly bigger than standard.

For the board itself we will use a matrix scanning design to get the most use out of our IO pins on the Pi. Currently with only 26 GPIO pins it may be difficult to get 40+ keys to work but that becomes a non-issue when using matrix scanning. With Matrix scanning for every ‘n’ pins we get ((n^2)/4) possible input combinations which means we have more than enough input.

 

 

 

 

 

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Team Status Report for 2/11/22

We reached out to Professor Carrington in the HCI department for advice on designing with accessibility in mind as that is his specialty. We cant design assuming that we know everything going into it and the only time available to speak with the professor was after the design review so we scheduled it then. In the meanwhile, we designed a preliminary  layout for the board that we think works well, which is based on existing one-handed keyboards.

On the technical side of things we decided on a few components that we are going to use. We’re using standard mechanical keyboard switches which will have custom caps designed and 3d printed. They will be slightly larger than normal to improve ease of use without being too bulky.

The Pi only has 26 GPIO pins but thats more than enough even for a 40+ key keyboard because we will be using matrix scanning to make the most use out of them. for every N input pins this gives us (N^2)/2 possible inputs, which is more than enough.

On the 

Matrix scanning works by taking in one row and one column of keys. Each key is connected to a switch (depicted as transistors), and when a key is pressed, it alters the voltage on the col pin, so it reads all the pins in the col. It then detects which pin by looking at which row. This efficiently reduces the time and number of pins, but only one key can be pressed at a time.