advanced audio recording
MIDI Matrix Router

To transport data with low latency a 16MHz bus mixer is implemented in the workstation. To mix from outside the workstation a 32 input / output MIDI board was created performing with 200 MBit of bandwidth and transports data  with only low latency.

The mixer is the same wich already was used in the S/PDIF Mix Matrix.

32 x 32 channel - mixer / router:

FPGA -MIDI Matrix Router 32x32 channels

The FPGA can easily handle 32x32 virtual MIDI channels and route them from and to any source and destination nearly no latency. To handle 2x2 times the mixer's capabilities, 16 sub mixers are used running on 16 MHz each. Thus 8x8 x n paths operate at 31,250bps.

4  classic MIDI channels are grouped together and mixed into one of 4 S/PDIF channels by using a 32 x 4 word input buffer and four switch lanes at 32 MHz raw bandwidth.

Unlike in the former switch version, all channels can be routed to all outputs performing like an Ethernet-router. Therefore all inputs are registered with a 2-word input buffer and eventually switch to a 8 word output buffer. So 8 MIDI-input channels can drive the same output at the same point of time without overloading it. Currently there is no commercial studio device which can do this.

32 channel - IO - PCB:

FPGA MIDI Switch Matrix 32x32 PCB

A new Cyclone II FPGA from Altera is used using Quartus Design Software.
The Design has been done with CadSoft-EAGLE.

Development has been done with a evaluation board system:

A 1024 channel MIDI Router with Altera Cyclone II FPGA

real time signal test
A test of the signal including latency measurement is performed by a usb-based logic analyser from Intronix. It is able to measure signal delays with a precision downto 4ns effectively

Intronix Logic Analyser GUI
Intronix GUI

Read about the former version: 

MIDI switch 32x32

full transmission
of all channels
one clock cycle

8 Bits

32 x 32 channels

full routing

96 kHz
Audio DSP


© Dipl.-Ing. Jürgen Schuhmacher 2005