Arduino leonardo keyboard tutorial1/9/2024 ![]() It just does the scans across the matrix (after figuring out which wires on the cable correspond to each key press). The original instructable for that project was based on connecting to the existing cable inside the keyboard. More pins, but only one shift resister.Īre you at all interested in detecting multiple keys pressed at the same time? That would need a different matrix scanning structure. Instead of 5 input pins, one per octave, plus 2 shift registers to walk across the 12 notes. If you could use 12 digital input pins, one per note, then you could use a single shift register to walk across the 5 octaves. Then detect a key press as low instead of high. The pinMode() function can be used to enable an internal 10K pullup resistor for input. The pull down resistors may not be needed at all. As setup, the sense pins are being held low all of the time. The ‘sense’ lines need to go directly to the Arduino pins. The 10K resistors you have are not setup correctly for that. With the general way your sketch is wired, you are trying to have one of 5 (octave) sense pins go high (only) when the shift register output matches the single note key being pressed. Depending what else (like that midi interface) is to be connected to the same Arduino. With the number of pins being used, an Uno would be plenty for this. With my background, that is easier to verify for correctness, then use the ratsnest lines to wire up the breadboard. I normally start with the schematic view, instead of breadboard. Don’t forget to ‘debounce’ the keystroke readings. I assume you intend a ‘matrix’ scan, to determine which key (or maybe keys) are pressed. Midi includes “velocity” information as well as the note. Simply sending a note on key press is not going to be “full” midi. The documentation link from there points to the repository on github, and the readme contains examples. The downside is that one needs an ISP to transfer programs on the micro.Assuming you also have a standard midi interface hooked to the Arduino (there is none in your sketch), you can use a library to send midi commands. For this reason I designed the Pancake board ( ), which has a USB connector that can be used in an arbitrary way. Here, a “USB-keyboard” only device needs to be implemented. An example, where this does NOT work is, for example, the iPad with iOS. ![]() This approach works as long as your target device works well with arbitrary aggregations of USB devices (usually every PC), because the Uno, Leonardo and other newer Arduino-like boards provide USB serial communication and USB keyboard/mouse/joystick at the same time. A very quick search for “Arduino Uno joystick” gave, for example. Older versions of the Arduino just provide serial communication capabilities with the USB connector (as far as I know). This would be possible with the Arduino Uno or newer. I used these schematic for setting up the button circuit: ![]() 2x 68R (i.e., “68 Ohms”) resistor, 1/4Wįor the assembling, we need a breadboard and some jumper wires.I have a Duemilanove, but I assume that any other board (even any other ATMEGA controller?) would also do. ![]() ![]() To setup the USB keyboard, we need the following parts: This example makes use of the Arduino 1.0 IDE and the fifth alpha release of the V-USB library. For a deeper understanding I give a list of usefull links that should help for an understanding at the end of this post. I do not want to repeat all the detailed explanations from these sources in the following, but rather show how to build a working example. This exemplary project is a summary from various sources. The V-USB library allows you to implement exactly the device descriptor that can be understood by the other device. This is useful, for example, if the device that you want to connect to can only handle certain types of USB devices. The motivation: The V-USB library provides a quite simple possibility to realize USB devices with arbitrary USB descriptors. I show, how an USB keyboard functionality can be implemented. This is another short example of a demo application that makes use of the V-USB library together with an Arduino. ![]()
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