Fatar Keyboard Scanning with Teensy

[cpynbo.123]

I am budgeting out/planning a MIDI organ, but I can't figure out a cheap scanning method. There are some similar threads on this forum, but none have the answers I need. I will be using three independent Fatar TP/9S keybeds and I want to know a solution to scanning them. I am very much a newbie to the world of circuitry. I don't necessarily need code recommendations, I am just looking to understand.

(1) Ideally, (If this would even work) I would have three separate Teensy/Arduino boards, each with their own output to USB. One keyboard to one USB/MIDI out.

(2) If it is possible, I would love to have each of them also have an output to MIDI through DIN, but I don't know if that sort of thing is possible (Attaching other outputs to Teensy besides the USB).

(3) Really, I just want to know if it would be possible to scan the keyboards to Teensy. If another board would work better, than that's fine. I want the least amount of latency possible.

Also, I am very constrained on price, so please do not recommend an $80+ board unless that would be the best option (lowest latency) or the cheapest for what it does. I only need the keyboards scanned. Any other features/gimmicks are welcome, but only if they don't add too much to the price.

The TP/9S uses two 16 pin ribbon cables for output.

 

[Nantonos]

I will be using three independent Fatar TP/9S keybeds and I want to know a solution to scanning them.

Sure. This is easily possible, once you understand 2 things:

1. Row/column matrix to scan the keybed. Fatar used to have a diagram showing this on their site but it seems to have been removed; look here instead and also the links from this post.
2. Diodes on the matrix to prevent "ghost keying" if more than two keys are pressed on the same row. See this guide for an explanation. The diodes are already present on your Fatar keybed.

The end result is that for, say, a 44 key keybed you do not need 44 input pins on the Teensy; instead you have a matrix of, say, 14 rows and 16 columns and, in a loop, for each row you read the columns (so, 16 pins).

If you are just looking at key down/up then that is all; for velocity you need to note the key down time as well (in milliseconds) and then look at the second set of switches to determine the strike velocity. Probably not needed for an organ.

Fatar use Micromatch connectors (1.27mm pitch, i.e. 1/20 inch). On the smaller keybeds they put both rows and columns on a single 20-pin connector, on the larger ones they spread this across two 16-pin connectors.

(1) Ideally, (If this would even work) I would have three separate Teensy/Arduino boards, each with their own output to USB. One keyboard to one USB/MIDI out.

Sure, that is easy.

(2) If it is possible, I would love to have each of them also have an output to MIDI through DIN, but I don't know if that sort of thing is possible (Attaching other outputs to Teensy besides the USB).

For USB see MIDI USB and for DIN serial see MIDI Library.

The TP/9S is a nice, well-regarded keybed, usually seen with unweighted or semi-weighted keys (ie not hammer action) which is what you want for an organ. It usually has velocity, and some have monophonic (channel) aftertouch although you may not need either for an organ which makes coding simpler. The key profile is rounded, making glissando easier.