Fox Cub Overview

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Fox Cub Overview

Please see the standard Disclaimers

More detailed documentation on Fox Cub can be found in the Fox Cub Documentation




Fox Cub is an Arduino Based RS485 Renard compatible dimming controller system that's designed to be very cost effective and simple to build / configure. The system has been designed to keep external cabling costs low. It also provides the ability to test channels and configure addressing in the field without the need for a computer during setup. Additionally it has a full 256 levels of dimming and on board zero cross detection. It can be used for centralized, decentralized or mixed layouts depending on boards used.


FoxCub16 (the controller board) is based around a minimalist Arduino, which is an Arduino with unnecessary parts removed. The design uses the ATMega328p, which is the most cost effective choice for the number of channels and distribution of lights around a layout. Software is uploaded via the Arduino IDE. The ATMega328 is the same chip used in the Arduino Uno / Duemilanove.


  • Compatible with Renard, uses the Renard protocol
  • 110VAC design. (240VAC will need adjustment for Zero Cross Detection).
  • Renard RS485 compatible, uses standard RJ45 connectors.
  • Wireless Capable, compatible with Ren-W with some minor changes.
  • Very cost effective
  • High channel count. Standard software handles 256 channels. Up to 1150 channels with minor software change and 115200 baud.
  • 60/50Hz - 256 levels of dimming with zero cross detection on board
  • In field addressing / baud rate configuration
  • In Field Testing (no computer required):
  • All Channel On
  • All Channels Dimming
  • Channels Stepping in Sequence
  • Larsen Scanner
  • Zero Cross Detector Operation Verification
  • One firmware, no need to switch firmwares for testing and operation.
  • Opto isolated from computer for protection
  • Optional repeater for decentralized layouts
  • Onboard test leds, 1 per channel, 16 in total
  • Easy build. Single layer, PCB's can be built at home. Could also be built on stripboard.
  • External 5V power to keep costs down
  • Runs at 4800, 9600, 19200, 38400 or 115200 baud.
  • Onsite programmable for software updates
  • Small, 8cm x 10cm
  • Inactivity Timer, lights switch off after 1 min if active communication ceases.
  • Works in colder temperatures too. All critical components are spec'd down to -40C, making it suitable for adverse climates in Alaska / Canada.

The Pieces and Layout

  • FCSquealer: Converts serial from computer to RS485 (opto isolated)
One required per display
  • FoxCub16: 16 channel controller
One required per 16 channels
  • FCRepeater: 4 channel RS485 repeater
Optional, used only in decentralized or very large displays
  • FCPowerInjector: Supplies 5V power to the system
One required per display
  • FCTerminator: Terminates an RS485 run
One required for centralized displays, or per every branch on decentralized or large displays

The following diagram illustrates the various layout options (click image for larger version):


Part Cost

(as of Dec 2012, supplier Mouser):

  • FCSquealer: $20.99
  • FoxCub16: $18.93 + $2.94(Zero Cross Detection) = $21.87
  • FCRepeater(4 Channel): $15.45
  • FCPowerInjector: $2.95
  • FCTerminator: $0.76

SSR Selection

Will drive AC or DC 4-Port SSR's at 50/60Hz. If you are driving DC SSR's, you can omit the AC components from FoxCub16. SSRNeon is recommend if you are home etching: SSRneon

Maximum Channels

FoxCub16 is a 16 channel controller which can be cascaded for more channels. The maximum number of channels is the same as Renard and is governed by your refresh interval and baud rate as per this chart: Renard channel limit.png

Ren-W Wireless

FoxCub16 is compatible with Ren-W, with some changes. By default, Ren-W provides RS232 voltage levels which are too high for the Renard RS485 used by FoxCub16. These changes solve that.

Baud rates have been tested for Ren-W up to 57600, which is the highest speed recommended for Ren-W.

The recommended Ren-W board is Rev 6.

Ren-W Construction

FoxCub16 changes to Ren-W

YouTube Video

Operational and Testing Videos:


This design pays homage to the wonderful work by the designers / contributors to Renard / SSRneon and this site.

Additional Disclaimers

This design uses high voltages. You are responsible for your own safety, make sure you know what you're doing or use a qualified electrician. USE AT YOUR OWN RISK.