Driving WAV trigger with USB/MIDI keyboard

Sensors Sound & Audio
1

Hi all,

Just ordered a WAV trigger and was looking to drive it with a MIDI keyboard. I’ve read that a MIDI breakout board can be used for this, but the newer MIDI keyboards send the MIDI info over USB instead of the 5-pin DIN connector. Can I use an FTDI breakout board to connect the USB keyboard to the WAV trigger?

Thanks.

2

Hi sparky7,

That might work here with the serial port configured for MIDI control. The only thing I’m not sure about is how the FTDI Basic is going to interact with the USB out from your MIDI keyboard. The FTDI Basic is designed to primarily be connected to a computer and requires drivers to be recognized as a USB device. Depending on how your keyboard’s output works, it might be possible with the FTDI Basic but you may need to do a bit more work to translate from USB MIDI Out to TTL input on the serial header.

There is a bit more information on MIDI setup in the [WAV Trigger User Guide on Robertsonics’ website that may help you out here.](http://robertsonics.com/wav-trigger-online-user-guide/#chapter10)

3

Hi TS-Mark,

Thanks for the reply. After looking at the info on this web page (https://www.midi.org/articles-old/basic-of-usb), it doesn’t look like it will work to connect a USB/MIDI keyboard to the WAV trigger through the FTDI breakout. According to the article and video, two ‘USB devices’ cannot connect directly to each other. They must connect to a ‘USB host’. Unless the WAV trigger can be configured to be a USB host, another device acting as the host would be needed.

Regards.

4

The WAV Trigger has a TTL serial port that can be set to receive MIDI data protocol. It’s easy enough to convert a real MIDI output (20mA current loop) to TTL serial with an opto-isolator - that’s what the MIDI breakout does. But a USB MIDI keyboard expects to be plugged into a USB host which can recognize a MIDI Class Compliant USB device. The FTDI-Basic is not a host, just a different USB device class - a serial COM device, which converts USB data from the host into TTL serial.

There is a small device that can be a USB Host which recognizes a class-compliant MIDI controller such as keyboard and will output the MIDI as TTL serial that could be connected directly to the WAV trigger RX pin.

http://www.hobbytronics.co.uk/usb-host/usb-host-midi

I’ve never tried it, but if it does what it says it does, you could theoretically use it to connect a USB MIDI keyboard to the WAV Trigger.

5

Thanks for the info – that appears to be what I’m looking for. It comes as a kit (which is ok), but the minimum order quantity is 10 and has to be shipped from the UK, bringing the cost to around $200… Know of any available from the US?

6

Sorry, I do not. Another approach would be to use a Raspberry Pi Zero (the one without Wifi is only about $5). Linux has a built-in driver for class-compliant USB MIDI keyboards (I’m assuming Raspian is the same), but you’d have to write the code to grab data from the keyboard and send it to the UART.

7

You can use an Arduino with the usb host shield https://www.sparkfun.com/products/9947

Google searching for “usb midi host arduino” turns up many hits

/mike

8

Thanks for the suggestions. This is intended as a Christmas present for my college-age son who’s in to music. To get started, we’ll likely just plug both the keyboard and the wav trigger (through the FTDI breakout) to a laptop computer. We may explore the other options later…