midi to rs232 bridge – for performance control of old video mixers & switchers

SKU: P003 Category:


the _transcribe_ circuit is a midi to rs232 serial utility module aiming to give better integrated performance capability to older/obsolete video gear.

some old video mixers and switchers have their own serial command specifications for externally controlling them. the arduino micro-controller in _transcribe_ runs open source firmware that maps incoming generic midi messages to these specific serial commands.

this allows you to (for example) use a deluge to rhythmically sequence wipes, trails and effects on a panasonic ave55 video mixer:

NOTE: although no coding background is required for this, you will need to be comfortable following install instructions and hacking at a few lines of arduino code to customize and set up your own midi to rs232 mapping ! underscores.shop distributes the hardware only – although we maintain the open-source firmware we have limited time for one-to-one tech support.


  • input USB-midi from a USB-HOST such as a computer or rpi
  • input serial-midi from older midi devices (din5)
  • input USB-midi from a USB-DEVICE such as a korg nanokontroller2 or otherwise
  • output RS232-serial commands over 3.5mm jack or dsub9 socket to control panasonic video-mixers and other devices
  • all these interfaces are bi-directional and so can be modified with firmware to do other useful things (eg like a USB-DEVICE midi -> SERIAL midi converter)

So far tested and supported with:
– Panasonic ave55
– Panasonic mx30/50 (partial)
– Extron video switchers
– Kramer video switchers

although in theory any device with a rs232 serial port and specification sheet documented is possible – let me know if you have success with something new.

this project – like everything in the underscores catalog – is fully open-source hardware – find all the source plus lots more information and guides on the github repo:

Additional information

Weight 130 g
video format


input type

midi-serial, midi-usb-device, midi-usb-host

output type

rs232-serial, midi-serial

power supply

5v over micro-usb