Channel Wizard: Add/mix/encode/decode PPM channels
I'm proud to announce Channel Wizard
, a small circuit designed to add RC channels
to the "PPM" signals that's used for control in most RC vehicles. It can also perform a multitude of other tasks either on the ground or onboard the aircraft, such as combining multiple PPM sources, make PPM compatible with long-range UHF systems, decode PPM to servo signals or create a new PPM signal from switches and pots.
This post is an overview. The manual
has more info.
Connect Channel Wizard to the PPM stream between the Tx and the radio module. Wizard can be connected to switches and pots to add up to eight extra PPM channels
. If the radio module can't handle enough channels, a "multiplexing" scheme is used to inject multiple inputs into one channel. Multiplexing also helps if the receiver doesn't have enough servo ports. When multiplexing is active, another Wizard is needed in the aircraft to extract the extra channels again. See Adding Channels
for a more complete introduction.
Note that adding channels requires basic electrical skills and soldering in one way or another.
In the Aircraft
Channel Wizard can also be used in aircrafts to decode PPM to individual servo signals, reverse, change trim and EPA. Here the Wizard ports are used as servo connectors instead of inputs.
Channel Wizard is designed to handle all common PPM forms and signal levels. It accepts voltage levels of 3.3-18 V so both trainer and module ports can be used, or the 5 V used internally in Tx'es.
For use in aircrafts, the circuit features power filtering to avoid brown-outs and protection against flipped servo connectors. The circuit is designed to be as small as possible: 8 grams and 40x30 mm (plus space for servo connectors) is about the size of a regular receiver.
Two push buttons and a wheel are used for setup.
Connect to Computer
Optionally use a serial cable and computer to make advanced settings, switch between transmitter and aircraft mode or upgrade the firmware. Advanced settings include combining multiple PPM input streams (for example headtrackers), treat PPM formats to make them compatible with LRS modules, generating sound, doing various channel mixing or doing control diversity (switching between two receivers to control all servos). This is setup with a powerful command line mode with dozens of commands and mathematical functions. In the future, the serial cable could also be used to control PPM from the computer.
Wizard has been tested with a number of transmitters and should be compatible with all major transmitter brands as long as the radio module accepts PPM. New 2.4GHz transmitters with integrated radio modules typically don't
use PPM except for the trainer port. Multiplexing doesn't work with 35MHz or 72MHz radio links yet. Long-range systems are supported (including 12ch for DragonLink) as well as all standard receivers.
Channel Wizard is available in limited quantity at the price $50. See Ordering details
Comments are welcome!
Adding 8ch via Futaba trainer port: