Next, repeat the same with the 4 cells to form a line of 8, then a line of 16 cells, and remove the last one to form a 15 keys row. Note that it is also possible to perform the move and place with the keyboard arrow keys and enter to validate. Now repeat the shift drag selection operation on both cells at once to duplicate them and form a 4 keys schema: Then click the left mouse button to validate. This will duplicate the selection (our cell), then move the mouse pointer so that the diode bottom pin is perfectly aligned with the first cell horizontal wire: Once done (if you also are following this for your design make sure the wires have the same size as mine), maintain the shift key depressed and drag a selection around the cell (wire included). This cell forms the atomic core of the matrix. Next wire them as in this schema (notice that there’s no connection between the vertical and horizontal wire): Let’s first design our key cell, by adding a SW_PUSH and a regular D diode. There are other ways to do it, for instance by generating the schema with this tool or this other tool.
It’s cumbersome to add those components by hand for all the 67 keys, so I’m going to explain how to do it with a selection copy. As I explained in the previous article, the matrix is the combination of one switch and one diode per key. It is possible to access this hierarchical sheet with the View → Show Hierarchical Navigator menu:Ĭlicking on the matrix will open this new (blank) schema sheet. The following window should open:īecause I’m designing the matrix, I named this new sheet matrix (yes that’s quite original). This can be done by pressing the s shortcut and clicking anywhere in the schema. Since the MCU schema is taking some space in the main sheet, I recommend creating a hierarchical sheet to place the matrix components. I’m going to design the electronic schema of 67 switches and diodes. Trust me, it will be probably the most boring part of this series. how to assign references and values to its components.how to design the matrix electronic schema.
This episode will cover the following topics: The first episode focused on the electronic schema of the keyboard controller.
Welcome for the second episode of this series of post about designing a full fledged keyboard from scratch. Thanks to Druz who discovered there was a mismatch between the reset button in the electronic schema and the footprint.I forgot that it will be under the PCB and thus everything is mirrored.