Cheaper Teensy Alternative?

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recon8659

05 Aug 2016, 13:23

I recently cut apart an AT101W in order to make a 61 key keyboard, but I was wondering if this
https://www.amazon.com/gp/product/B012FOV17O
would be a viable alternative to the Teensy.

Thanks for the help in advance

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Wodan
ISO Advocate

05 Aug 2016, 13:24


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recon8659

05 Aug 2016, 13:26

ah. thank you so much

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Wodan
ISO Advocate

05 Aug 2016, 13:27

Thank Scottc, he did all the research :)

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recon8659

05 Aug 2016, 13:31

Wodan wrote: Thank Scottc, he did all the research :)
Another quick question if you know the answer, since this has about 18 usable pins, from my basic grasp, does that mean a keyboard matrix could use 9*9=81 possible inputs/keys, or does that mean it would be able to accept 18*18=alot of possible keys.

ty

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scottc

05 Aug 2016, 13:35

I think it's something like 14 usable keys, don't remember whether that's accurate though

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recon8659

05 Aug 2016, 13:40

scottc wrote: I think it's something like 14 usable keys, don't remember whether that's accurate though
14? that can't be all can it?

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scottc

05 Aug 2016, 13:45

Sorry, brainfart. I mean usable PINS, not keys. I think there was discussion in the thread about the number of pins, but can't find it.

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recon8659

05 Aug 2016, 13:46

scottc wrote: Sorry, brainfart. I mean usable PINS, not keys. I think there was discussion in the thread about the number of pins, but can't find it.
So the power for all of them would come from the VCC, and all the inputs would be, if its 14 inputs, up to 14 squared which is 196 keys?

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recon8659

05 Aug 2016, 13:47

recon8659 wrote:
scottc wrote: Sorry, brainfart. I mean usable PINS, not keys. I think there was discussion in the thread about the number of pins, but can't find it.
So the power for all of them would come from the VCC, and all the inputs would be, if its 14 inputs, up to 14 squared which is 196 keys?
that doesnt make sense to me anymore, would all the pins actually go to a ground?

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scottc

05 Aug 2016, 13:49

No...

14 pins would mean at most a matrix of 7 x 7 = 49 keys. I'm not sure about the actual number of usable pins, but it's low compared to a Teensy.

Edit: You can get Teensy clones from China for like $10-13 if you need the extra pins and really can't afford a Teensy.

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recon8659

05 Aug 2016, 13:50

oh thats unfortunate, so I would need to find a board with at least 16 I/O pins

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scottc

05 Aug 2016, 13:55

Like I said, I'm not 100% sure about the number of usable pins. That's something you'd need to verify before making a decision.

Findecanor

05 Aug 2016, 15:38

The Arduino Pro Micro has 18 bidirectional digital pins. Some pins on the AVR can also be used for special purposes such as serial, timer input, PWM output, etc. and they are therefore sometimes labelled by those functions which can be confusing.
Arduino makes it even more confusing in that it does not necessarily map its pin numbers to AVR ports and bits in any sensible way and I think it can be different for each Arduino board.
Here is the mapping:
ArduinoProMicroPinout.png
ArduinoProMicroPinout.png (343.29 KiB) Viewed 2797 times
In the figure above, Pxy stands for digital port x, bity.

Unlike the Teensy 2.0, The Arduino Pro Micro is made to run on batteries so it has a built-in voltage regulator.
There are two variants of the Pro Micro: One which feeds the AVR 3.3V, and one which is made to feed it 5V - the 5V version being the most common. If it does not say, it should be the 5V version.
If you do feed it with +5.0V from USB, however, there is a penalty - the voltage regulator will deliver only +4.9V.
The AVR should run well on 4.9V, but you could also bypass the voltage regulator by bridging J1 with solder.
RAW = +5V from the USB port (or power IN if you use battery). VCC = +4.9V (or 3.3V) from the voltage regulator, or +5V if bypassed.
On 3.3V, the AVR is limited to 8 MHz and the firmware needs to be made for it but since most firmwares are made for the Teensy 2.0 which runs always on 5V, if you have the 3.3V of the Pro Micro you should bridge J1 to run that firmware.

There is a thread in the Workshop area How to use a Pro Micro as a cheap controller/converter with more discussion and info.
(This thread too belongs in the Workshop ;) )

Edit: I saw now that the other thread was already linked to. Sorry
Last edited by Findecanor on 05 Aug 2016, 16:03, edited 2 times in total.

User avatar
Laser
emacs -nw

05 Aug 2016, 15:58

You could try this one (more pins) https://www.arduino.cc/en/Main/arduinoBoardMicro (arduido micro, NOT pro, with reset button). I used it instead of a teensy with soarer's controller to revive a Bigfoot (model f keyboard). See here: post192171.html#p192171 (two posts below, there's a table whose first 2 columns show the mapping between the pin notations for teensy vs. arduino micro)

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