PPM signal support for FS-i6 radio

FlySky FS-i6 (or branded Turnigy TGY-i6) is a very decent 6 channel entry level RC radio system. But support for PPM (CPPM) standard is somehow not clear. I have no idea why manufacturer keeps PPM support data so well hidden. Anyway, here it is: how can I enable PPM on i6 radio system?

FlySky FS-i6 (Turnigy TGY-i6) 6 channel 2.4GHz radio system with FPV mount

PPM signal is supported only on FS-iA6B (v2) receiver, FlySky FS-A8S Mini receiver and a couple of compatible ones: FlySky Pro Micro, FS82 Micro Receiver and iRangeX Tiny 2.4G 6CH Flysky Receiver

FS-iA6B v2 receiver with PPM and i-Bus

No PPM on FS-iA6 receiver

It is not possible to enable PPM signal on FS-iA6 receiver. So if you have simpler one, you would have to buy iA6B. Also, PPM signal is not enabled by default. To turn it on, you have to change radio settings:

  1. Open Menu and select “System setup” FS-i6 system setup
  2. Enter “RX Setup”FS-i6 RX setup
  3. Navigate to “PPM output”FS-i6 PPM Output
  4. And change it to “On”FS-i6 receiver PPM Output

This is all. From now on, FS-iA6B will output PPM 6 channel signal on port 1 labeled “PPM/CH1”.

You can get FS-iA6B from here.

PWM, PPM, and Serial RX explained

When speaking about radio systems for remote controlled models, multirotor, airplanes, gliders, there are some shortcuts that might be unknown for beginners. Those are: PWM, PPM, Serial RX, S.Bus. Today I will explain basic concepts behind them, and when they are used.

PWM

PWM, as Pulse Width Modulation, is something a standard for controlling different devices onboard remote controlled model. Almost all servos, ESC, flight controllers and radio receivers can work with PWM signal. There might be some exceptions, but they are so rare, that we can skip them.

Stick (switch, POT) position in PWM signal is encoded as length of signal. Signal that lasts 1000us encodes minimum stick position, and signal of 2000us encodes maximum stick position.

3 PWM channels connected to FlySky FS-iA6BIn PWM, each channel is available as separate port of 3 pins (Ground, +5V, Signal). So, if receiver has 8 channels in PWM mode, that means that it has at least 8 ports of 3 pins. 24 pins, 24 cables, lots of mess. And this was great for airplanes, where each control surface is controlled by separate servo connected directly to the receiver. But is not so great for quadcopters and event airplanes with flight controller. Not only it requires a lot of cables, but also complicates things on flight controller’s end. It requires an interrupt for each channel, takes a lot of space and to be honest, it’s completely not needed. Why? Because we have something better…
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