Custom OMM PPM Adapter v2

This highly specialized device is a PPM adapter for the futaba 617FS rx that converts the PPM to single PPM composite signal.


OMM Rx Converter Rev2
The converter board is the second revision of a clever design by Mike Cook, alias Old 
Man Mike. His design allows several of the Futaba FASST receivers to be used with 
quadrocopters that require a single PPM composite signal. It plugs directly into the 
receiver outputs, then generates a single PPM composite signal. There's a jumper that 
allows you to set 6 or 7 channel output as with the Rev1 version, but this Rev2 version 
has a new jumper position, to add a new mode for the Spectrolutions folks. The new 
mode allows you to control Ti on/off, and sensitivity with channel 5 alone, which 
means that channel 6 and 7 can be available for use with other servos. The LED 
shows the channel mode on initial power-up, and also flashes to show an active signal 
being received. 
The Rev2 board also provides connectors to access channels 6 and 7, where the Rev1 
did not. If you wish to use servos on channels 6 and or 7, you must make sure you 
have sufficient power to drive them. I believe the Spectrolutions board is the only 
board with this issue, but there could be others. There is also a separate plug that will 
allow an ESC BEC cable to be plugged into the converter if needed. 
What will it work with?
The converter is currently known to work with the following combinations of 
receivers and copter electronics. Others will be added as they're tested. Note that 
R607FS and R617FS receivers are both 7 channels, but the timing of channel 6 and 7 
is not the same. This converter board only allows 7 channel operation with the 
R617FS receiver. 
Note that the converter will not work with the 8 or 14 channel FASST receivers . Failsafe note- The Futaba FASST receivers hold the last known good signal, so if you 
lose your radio link the receiver will still provided the last known signal to the quad. 
This is a good news/bad news sort of feature. It's good because a brief signal loss 
won't be much of an issue, but it's bad for systems that have a failsafe which depends 
on being able to recognize a lost signal. As far as the quad will know, you are just not 
moving the sticks, but the signal will still appear valid, so the failsafe will never kick 
Spectrolutions Experimental Brushless board (OMM's 
Kquad Thread)
- Spectrolutions mode with R606FS, R607FS, and R617FS receivers.
- 6 channel mode with R606FS, R607FS, and R617FS receivers. 
- 7 channel mode should not be used with this board. 
If you don't plan to drive servos, the Spectrolutions board provides enough power for 
the receiver and converter. In this case, the cable needed to connect the 
Spectrolutions board to the converter is a simple 3 wire cable. A servo extension wire 
works well. The female end plugs into the converter. The male end has a protective 
plastic shell around the pins, which needs to be removed before you can plug it into 
the Spectrolutions board as shown (install photo). 
If you plan to drive servos with channel 6 and or 7, you must provide additional 
power to the converter from an ESC. If you try to drive a servo using only the power 
provided by the Spectrolutions board, there's a very real chance the signal will 
become disrupted, and the Spectrolutions board will shut down. As you can imagine, 
this wouldn't be a good thing to have happen in flight. A standard Y splitter cable 
from one of the ESC's should do the trick. It will be plugged into the aux power 
connector. When using this cable for power, you should cut the red (center) wire on 
the cable that goes from the convert output to the Spectrolutions board. This prevents 
the two power sources from interacting. The ESC will now be powering the receiver, 
converter, and any servos. 
Unless you absolutely need to use channel 6 for something else, I would recommend 
using the normal 6 channel mode for the Spectrolutions board. The clever new 
Spectrolutions mode allows the converter to create channels 5 and 6 using only the 
channel 5 input from the receiver. Support for setting this mode is best requested on 
the OMM Kquad thread, since Mike has the most experience with it. Mikrokopter
- 6 channel mode with R606FS, R607FS and R617FS receivers. Most people seem to 
want more channels, so I don't imagine this will be a popular mode. 
- 7 channel mode with R617FS receivers. 
- 7 channel mode with R617FS receivers. 
This is only needed if you wish to use the gyro stabilized output for camera tilt and 
roll, AND also want to manually control tilt and roll. 
- 7 channel mode with R617FS receivers. 
- 6 channel mode with R606FS, R607FS, and R617FS receivers. 
- Not tested, but it can be made to work with a very simple modification to the board. 
Contact me for details if interested. 
How does it work?The above photo was posted by Mike on the OMM Kquad thread. It shows all the 
connections and jumper positions. Ignore those extra 3 programming pins, since they 
aren't on the converters that I made. 
The 3 pin RX Serial Output plug connects to your quadrocopter electronics via a 
normal servo connector. Orientation is marked by red and black dots on the edge of 
the converter board. Power and ground are from the quadrocopter, and the signal pin 
is PPM composite signal output from the converter to your quadrocopter. 
Power and ground for the converter, and your receiver is normally supplied by the 
quad electronics through the red and black pins on the RX Serial Output plug. This 
should be typical receiver voltage of around 4.8V. The PIC processor chip has a max 
voltage rating of 6.5V, so don't exceed that. If you plan to drive servos from the 
converter, make sure you're quad type supplies enough power for this. The 
Spectrolutions board does NOT, so additional ESC power is required at the Optional 
Power Input plug, using a standard Y splitter cable from any ESC. When connecting 
this, it's a good idea to cut the power wire on the RX Serial Output connector, so the 
two power sources don't try to interact. 
The jumper selects 6 channel, 7 channel, or the new Spectrolutions (5 in/6 out) modes 
of operation. See the diagram for jumper positions. This is read during power up, and 
will not change afterwards, even if the jumper is moved, or removed. 
The LED confirms channel mode. Apply power without the transmitter on and the 
card will tell you which mode it is in: 
-One flash is 6 channel mode (R606FS, R607FS, and R617FS receivers) 
-Two flashes is 7 channel mode (R617FS receiver only)
-Three flashes is Spectrolutions mode (R606FS, R607FS, and R617FS receivers) 
There's an additional caveat to using 7 channel mode with the R617FS. Due to the 
timing that Futaba set for the output of the pulses, if channel 7's pulse width is near 
the max, it starts to interfere with the beginning of channel 1. For this reason, you 
will need to set your EPA for channel 7 to less than 100%. On my 7C, the magic number is 83%, but I'd go for 80% to be safe. Since channel 7 is a switch, this should 
not cause any problems. 
If you don't reduce your channel 7 EPA, you will find that it works just fine with the 
channel 7 switch in one position (shortest pulse width), but when you flip it to the 
other position, your roll axis (channel 1) will appear to have a large trim change. If 
you trim it out, then flip channel 7 back to the other position, the large trim change 
will be in the opposite direction, back where you started from.
Common Sense Disclaimer- These converters are tested before I ship them, 
and if you have problems, I'll help you get it working, or will refund your money 
when you return it. You will be responsible for making sure it works properly with 
your quad, before you fly it. Flying R/C models can cause injuries and property 
damage, and neither I, nor Mike will accept any responsibility for injuries or damage 
resulting from the use of these converters. Purchasing a converter acknowledges that 
you accept this responsibility
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