pcm2704 questions

[JAY X]

Hi!

I recently bought a USB pcm2704 dac very cheap. It is also available at Mouser to build your own pcb.

I thought it is an interesting piece to build around other circuits, and transmit data over USB.
Specifically i would like to build a small MIDI controller with an arduino, and send the MIDI data through usb, while i receive audio through the dac outputs.

The first idea i had to do that is to build a small USB hub with 1 input and two outputs. The input would be for the cable comming from the computer, and the two "outputs" for the MIDI controller to send data to the computer and the second "output" for the DAC to receive audio data from the computer...

I'm not a digital geek... so I ask here if there is a way to transmit/receive MIDI and receive audio through a single usb cable.

Jay x

 

[ccaudle]

a way to transmit/receive MIDI and receive audio through a single usb cable.

The USB protocol uses the term "endpoint" to refer to the logical receiver of a data stream. A single physical component can have multiple logical endpoints, so typically for something like a USB audio interface with MIDI capability there is a single processor which acts as an audio interface and a MIDI interface, and sends audio data to a separate DAC (usually using I2S interface), and MIDI data to the output transceivers needed for MIDI.

Since you already have a direct USB interface DAC you would need a USB hub, which is the term for a device which connects multiple USB devices to a single USB host. Your computer may have one inside already for connecting various external USB ports to a single host port in the chipset.

Multiple vendors make USB hub devices.
USB hubs at TI
USB hubs at Microchip
USB hubs at Infineon

Designing USB hubs is not very interesting though. Why not just get Amazon to deliver you a $5 USB hub tomorrow so you can get to work on your DAC and MIDI interface?

 

[JAY X]

Hi!

My idea is to embed both the USB dac and midi controller into an analog audio board... But, yeah, as a starting point, i'll better get a usb hub and experiment...

Jay x