Walkera DEVO for the 9x TX
I have been flying a Genius CP (DEVO) with a 9x for a few days now and while I probably don't have all the issues worked out I figured it's time to post some information. This will be a continuous work in progress.
BEWARE, the MTC-01 is known to be flaky at times and especially running this nonstandard configuration it could be dangerous. This is for informational purposes only, everything below could be incorrect, don't try this at home.
First a quick start for the impatient:
- Models created to be used with the MTC-01 should use a 23.5ms frame time with 400us pulse separator length. Do not use more than 8 channels (less is better) and if you're using an old MTC-01 with the original firmware it is a good idea to set any channels you're not using to -100 to help prevent the "channel mixup" issue. Newer MTC-01's don't have this problem.
- Binding requires first plugging the MTC-01 into your 9x, then turn on the DEVO RX, finally turn on the MTC-01. MTC-01 should have a solid blue light and the DEVO RX should have a flashing light.
- Next wiggle the stick, switch, or whatever that is on channel 2. The MTC-01's blue light should start flashing. Within a second or two the DEVO RX's light should go solid.
- Wiggle the stick on channel 2 again. Now the MTC-01's green light should start flashing. Within a second or two the DEVO RX should initialize (on my Genius CP the heli "comes alive" and wiggles the collective at this point).
- Now you're ready to fly.
Once bound if you do not power off the MTC-01 then it will rebind to the same RX automatically without having to go through the steps above.
Apparently there are two versions of the MTC-01, the new one just being released recently. Lets call these v1 and v2. I do not know what the differences are but there are hardware changes and probably firmware. Supposedly the v2 fixes some issues with failsafe and possibly the "channel mixup" issue. There is also a new firmware for the v1 that fixes the "channel mixup" issue but it's unclear if that actually fixes it or not.
The channel mixup issue is where the MTC-01 will get out of sync with the PPM stream and start transmitting the wrong channels to the receiver. In other words the channel order gets mixed up. Obviously this is very bad and dangerous when flying.
The failsafe issue comes in to play if you disconnect a v1 MTC-01 from your radio while it's still powered on. Apparently it can start sending random channel data like full throttle to your model. If that happens you need to turn off the MTC-01 as fast as you can, this will hopefully send your DEVO RX into its own failsafe mode.
My MTC-01 is a v1 and it also runs the old buggy firmware. This is all I have experience with and is what all my testing has been done with. I would be happy to try a new v2 MTC-01 or upgrade the firmware on mine if someone sends me one of the v2 MTC-01's and/or a DP02 firmware upgrade cable.
Alright, lets get into the details.
The first thing that needs to be done is to connect the MTC-01 to the 9x. The MTC-01 comes with a cable that can be plugged into the 9x's trainer port and this works fine. However, I put my MTC-01 board inside a 9x style TX module. This gives me a little more range because of the better external antenna and I power the MTC-01 from my radio so I never have to worry about its battery. I built a small PCB that has a 3.3V voltage regulator to supply power and connect to the 9x module pins. The audio plug needs to be removed from the board for it to fit in the case. The internal antenna can be removed and coax soldered in for an external antenna. I'm thinking of adding an RF amplifier in there as well to get a power boost and more range.
Once the MTC-01 is connected to the 9x now we need to create a model. I'm using er9x on my 9x which gives great control of everything. Other firmwares may be slightly different or possibly not work at all if they can't be configured properly, let me know.
Some adjustments need to be made to the PPM signal for the MTC-01 to recognize it. The frame length should be no longer than 24ms. I use 23.5ms. The most important setting is the pulse separator length should be 400us. The MTC-01 will also accept 350us but I have had problems with glitching when using that timing. My WK radio actually uses around 423us so I'm not sure how precise this value needs to be. On the v1 with the old firmware my guess is the channel mixup issue is caused by the PPM frame sync pulse not being long enough so if you use too many channels or too many channels have long enough pulses then the MTC-01 goes haywire and loses sync. To avoid problems either run less than 8 channels or with 8 channels I run the longest frame time I can and I set any channels I'm not using to -100 which makes their pulse as short as possible therefore giving a longer sync pulse.
See the quick start above for binding information.
Well, that's it for now! Simple right? Now the hard part,
, I will make a follow up post below to describe how I set up my Genius CP to work with my 9x.
to this cause