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geekhack Projects => Making Stuff Together! => Topic started by: 0100010 on Fri, 22 November 2013, 20:18:48
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Probably a dumb question, but is there a list of the maximum number of columns and rows that each Teensy variant could support?
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Depends how you read them
(http://www.openmusiclabs.com/wp/wp-content/uploads/2011/10/switch_marix.jpg)
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Probably a dumb question, but is there a list of the maximum number of columns and rows that each Teensy variant could support?
Number of available pins I/O pins = the sum of number of rows + number of columns. The Teensy 2.0 has 25 pins and the Teensy++ 2.0 has 46.
The Phantom uses all pins on the Teensy 2.0, with a 17×6 matrix and 2 LEDs. (17+6+2 = 25)
Note that the built-in LED is also on pin D6. On the Phantom, this LED is pulsing very fast all the time, faster than the eye can see.
It could instead have been a 8×13 matrix, and left the D6 pin alone, but the routing of that would have been a little bit more complex.
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Thanks guys.
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You can add simple decoders (http://www.electronics-tutorials.ws/combination/comb_5.html) to increase the number of rows (or columns). They are one-way - can be used only as outputs. Multiplexers (http://www.electronics-tutorials.ws/combination/comb_2.html) do pretty much the same a bit more complex and can be used on inputs as well. The next step is using an IO-expander which communicates serially with the controller. In theory you probably can expand a single pin to as many as you like serially, but that's more work than fun. All of the above come as through hole components, and should be quite easy to position somewhere. An only slightly harder package to solder is the SOIC surface mount.