Thread Tools
This thread is privately moderated by North_of_49, who may elect to delete unwanted replies.
Feb 23, 2014, 04:08 PM
Scout CX | mCX2 | mSR | 120SR
North_of_49's Avatar
Thread OP

Spektrum DX9 sequencer - strobing an LED

I was asked to do a blog post about this...

click image to watch at YouTube

I won't go too in depth into the basics of using and setting up the DX9 sequencer; There are some good sources for that already. I highly recommend checking them out first before continuing with my post if you really want to understand what I'm about to write here if you don't already.

There's a great introduction to sequencing in the March 2013 issue of Flying Models magazine...

Apparently you can purchase a download of a single issue from within the free Carstens app...

I understand that, at the time of this writing, this is the only way to buy a single issue and in electronic format, and that it is currently only available for iOS (Apple) devices. There is some discussion about this here...

Alternately, you can find pretty much the same information on RCG member freechip's blog and YouTube channel...

EDIT: freechip wrote that article and has now made it freely downloadable. I'll update with a link soon.

Setting up the sequencer to strobe an LED
I was able to figure this out with help from RCG members freechip and Andy Kunz (Andy posted a sample strobing sequencer file in the DX9 thread for me to analize and play with... mine is a modification of his). Big thanks to both of you!

This is what I wanted to do. A sequencer has a timeline and it has both a forward and reverse direction and it can be set up to play continuously and automatically reverse direction when it gets to the end and beginning of the timeline. I wanted to place a short pulse on the timeline that gets triggered over and over at a regular interval as the timeline plays forward and back again in a continuous loop...
Name: DX9-LED-Sequencing-001.jpg
Views: 54
Size: 44.8 KB

To take this a step farther and make it into a double pulsed strobe, I knew all I needed to do is place the pulse near either end of the looping and self reversing timeline and it would get triggered twice as the the sequencer triggers it once, then reverses direction and immediately triggers it again. I placed the pulse close to the left end of the timeline... when the sequencer plays backward from the end of the timeline, it triggers the pulse then reverses its direction and triggers it again right away, then there is a delay until the sequencer gets to the end of the timeline again, reverses, and the same thing happens again, continuously...
Name: DX9-LED-Sequencing-002.jpg
Views: 62
Size: 73.0 KB

The DX9 has 2 sequencers. If you download and import my .spm sample model and go to the sequencer, you'll see in the 1st screen I'm using sequencer #1

NOTE: I had to power cycle my DX9 after importing the model or some stuff in the sequencer switch assignment screen didn't show up properly. Sequencer switch assignment was set to INH and I didn't have "Switch" on the next screen as one of my options to set it to until I power cycled the radio... do this power cycle immediately after importing the model from the SD card!

Note 2: this .spm now has the strobing (via a remote switch) set up on AUX1 (as per my other blog entry on switching the strobe via a toggle on your radio) and not GEAR as described in this blog entry. And some of these screen captures and steps will no longer apply if you take this to the next level and set up toggle switching of the strobe. This blog "how to" is for setting up a non controllable constant strobe and some things in this download-able .spm file will be different from what I'm describing here. You can edit the model to match what you see here though...


This is what you should see when you enter the sequencer if you've power cycled the radio after importing the model (EDIT: see note 2 above)
Name: sequencer_names2.jpg
Views: 86
Size: 46.6 KB

Choose the first sequencer and in the next screen you'll see some things that were set up for the strobe including...

- the switch that you want to use to activate or run the sequence... in the end, you want to set this to a virtual switch that continuously self-toggles (in the two screen captures below, you'll see I took it off the self-toggling "Switch" and put it on the DX9's manual physical "Switch A" toggle switch temporarily to stop the auto-looping of the timeline so you can adjust the settings, once the timeline settings have been scripted you'll want to change this back to just "Switch" which makes the sequence auto run... more on that in the next section)

- the speed the timeline plays at (separate settings for Forward and Reverse)

- give names and abbreviations to sequencer #1's two channels

- the receiver channel you want to output to, where your LED is plugged into via a remote switch of some sort (Gear in this case... NOTE: I had to reverse my Gear channel in the servo setup or else my LED was ON when it was supposed to be OFF and vice versa)

- the timeline event type you want to use. In this case, it should be set to "Step" so the 0 1 2 3 4 timeline events on the next screen are instant on-off to create a pulse, rather than ramped over a period of time like slowing a servo which won't work with an LED anyway, even if you wanted it to (you can't ramp the brightness of an LED over time or even turn one on and off using the sequencer alone... a transmitter only sends out a control signal to a receiver port's signal pin, it' can't dynamically control the current or voltage on a receiver port's power pin, in fact, it can't control the power pin at all in any way... you'll need to connect the LED(s) using some form of what's called a remote switch when you physically connect it (them) to your receiver. What the sequencer is then controlling is the remote switch, not the LED directly, but more on that later).

Each sequencer has an A and B channel. You'll only need to assign the "A" channel to an actual receiver port. See more on this in the red writing below.
Name: sequencer_switch.jpg
Views: 70
Size: 60.1 KB
Name: sequencer_page2.jpg
Views: 56
Size: 49.5 KB

If you want to view and/or alter the sequencer's timeline settings in the 3rd screen, you'll need to stop it from playing and auto-looping. You do this by going back to the 2nd screen and taking its assignment off of the virtual "Switch" and assign it to one of your DX9's physical toggle switches (shown in the two pictures directly above). For example, assign it to Switch A. Now when you go back to the timeline screen you'll have stopped the auto-playing and looping and will be able to access the settings for both the forward and reverse directions of the timeline. Toggling the DX9's physical "A" switch back and forth while viewing the timeline screen lets you see and access the settings for both directions... in this case they should be set to be the same thing in both directions. You'll also see the timeline play out in real time for each direction as you toggle the switch back and forth... it'll happen quite quickly because I have the sequence set up to cover the entire timeline in about half a second in each direction. Once it gets to the end (or the beginning, depending which position your toggle switch is in) it will stop playing and you can view and adjust the settings of the 0 1 2 3 4 events.

In the timeline screen (observing the top channel or top half of the graph), I set my 0 1 2 3 4 events up as shown in the following pictures... this creates the short pulse and positions it on the timeline the way I described with graphics back at the beginning. Take note of the little arrow which shows you which play direction you are setting up the 0 1 2 3 4 events for... you'll have 0 1 2 3 and 4 for each direction. The bottom half of the timeline, Channel B, has to be set up like in my pictures as well (the values for the XXX positions)... to be honest, I can't remember why, but I just went in and changed those values and everything stopped working. If I remember why, I'll edit this.

It's coming back to me now. I think this channel of sequencer #1 (Channel B named as XXX) is just being used as the control track that drives the timeline forward then reverses it and runs it backward and keeps it looping. This is what the sequencer is using as the auto-playing and auto-looping virtual switch when you eventually assign the sequencer to "Switch" in the switch assignment screen. The reason you leave XXX inhibited (INH) in that settings screen beside "Chan B:" is because that setting is for receiver channel output and you are just using the XXX channel as a control track for the other channel (STR) which is the one that actually gets output to a receiver channel (GEAR)

Name: sequencer_page3_forward_point-0.jpg
Views: 67
Size: 49.6 KB
Description: Name: sequencer_page3_forward_point-1.jpg
Views: 64
Size: 50.6 KB
Description: Name: sequencer_page3_forward_point-2.jpg
Views: 59
Size: 53.2 KB
Description: Name: sequencer_page3_forward_point-3.jpg
Views: 62
Size: 49.9 KB
Description: Name: sequencer_page3_forward_point-4.jpg
Views: 68
Size: 55.9 KB

Name: sequencer_page3_reverse_point-0.jpg
Views: 64
Size: 54.0 KB
Description: Name: sequencer_page3_reverse_point-1.jpg
Views: 65
Size: 54.9 KB
Description: Name: sequencer_page3_reverse_point-2.jpg
Views: 68
Size: 55.2 KB
Description: Name: sequencer_page3_reverse_point-3.jpg
Views: 63
Size: 53.9 KB
Description: Name: sequencer_page3_reverse_point-4.jpg
Views: 52
Size: 47.0 KB

Once the timeline is set up, back in the 2nd screen the assignment needs to be taken off the physical "A" toggle switch and set to the virtual "Switch" which will be the very last one in the list of choices. The sequence will now auto run and auto loop and you'll see evidence of this happening in both the timeline screen and this screen in real time...
Name: sequencer_switch.jpg
Views: 70
Size: 60.1 KB

To mimic a true strobe, I wanted the duration of my LED pulses to be as short as possible. At first I set up my timeline events to give my pulse a duration of 1% and I had the Speed set to 0.5 (0.5 seconds) in both directions... this is the amount of time it takes for the entire timeline to play out which would then be one second (half second Forward and half second Reverse). This sometimes wouldn't trigger my actual physical LED, so I changed the duration of my pulse to 2% using the 0 1 2 3 4 timeline settings and slowed the Speed down to 0.7 as shown in the picture directly above. By changing the Speed of either the Forward or Reverse direction by just one value (can't remember which, I'll have to check) I was able to create a double strobe pulse during the first time through the sequence followed by just a single strobe pulse during the second run through the sequence and that kept alternating, which is what I wanted in the end. Accomplishing that was just sort of a fluke due to the Speed running too fast in one of the directions for it to actually trip the LED twice every other time it ran through the sequence.

You can slow the sequencer right down so you can watch and better see in real time what's happening in the timeline screen... and also the DX9's main servo monitor screen. Try slowing down the sequencer's Forward and Reverse speeds to 4 seconds each and then watch the DX9's main servo monitor screen on the Gear channel which will now show up with the name STR which is what we named it in the sequencer settings ... watch closely what happens to the servo position marker every 8 seconds. Try going into the sequencer's timeline screen and watch the timeline's play position indicator go back and forth

Next, I'll explain how I actually physically hooked up an LED to a receiver channel in a way that the sequencer can run it (using a remote switch) ... to be continued
Last edited by North_of_49; Apr 23, 2016 at 07:52 PM.
Sign up now
to remove ads between posts
Mar 21, 2014, 01:19 PM
Closed Account
Last edited by ClosedAccount; Jun 16, 2014 at 10:00 AM.
Mar 21, 2014, 03:24 PM
Scout CX | mCX2 | mSR | 120SR
North_of_49's Avatar
Thread OP
Steve, it's the very last one when you' scroll through them all. Sometimes I didn't see it there, I can't remember what circumstance created that situation or if I even figured out why. It might have been the thing I first highlighted in red above about having to power cycle the radio for it to be created and show up in the choices. I know that's a "must do" during this whole process, am just trying to remember if the reason for it is because of the issue you brought up. Reading my own post (and remembering a conversation I had with freechip in a pm), it would appear so... I think that procedure applies to creating the switch in the first place from scratch as well as when importing my model. Try power cycling the radio and let me know what happens.
Last edited by North_of_49; Mar 21, 2014 at 03:43 PM.
Mar 21, 2014, 08:51 PM
Closed Account
Last edited by ClosedAccount; Jun 16, 2014 at 09:59 AM.
Mar 21, 2014, 09:15 PM
Scout CX | mCX2 | mSR | 120SR
North_of_49's Avatar
Thread OP
Originally Posted by {}{steve}{}
Did you also tie yours to a mix? I'll have to take screenshots because I can't remember everything I did, but I had to remap the gear channel to an unused AUX channel, then reverse the channel, and the assign the mixes to the physical switch. I still don't understand exactly what I did, but it works
I'd have to go look at mine, but where I mapped my stuff to was just an example... you can use whatever channel you want and whatever switch you want for that channel (you do need to actually assign a switch to the channel... to be clear, this is the master switching of the LED from "strobe" to "always-on" or "completely off" I'm talking about... not setting up the strobing itself in the sequencer. It's discussed in the other blog thread of mine regarding master switching the LED, which is the next step someone might want take things to after getting what's discussed in this thread working ).

But, regarding what's actually being discussed in this thread, I did have to reverse the channel my LED was on to get proper order of the duty cycle of the actual flashing (on-time vs off-time). This could also have been done directly on my remote switch (the physical component plugged into my receiver that my LED is hooked up to), it has its own reversing capability using a little DIP switch on the circuit board.

But, again, the actual switching of the LED from Off to ON SOLID to STROBE is discussed in my other topic on my blog.
Apr 07, 2018, 08:45 AM
Bank & Yanker!!
prawlin's Avatar
Thanks for all this looping sequencer info. Yesterday, I spent the entire day losing my sequencer virginity on my DX8 G2. I now have double flash sequence wing tip red/green very high intensity 180 view angle Lambertian LEDs set up. I switch the sequencer output via mixing on 3 position switch B to give Lights off/Lights On (strobed)/Lights On (continuous). So cool.

It's a tricky subject to understand, especially at first but I think I'm getting it now. Will be interesting to see if I can manually do it again from scratch on another model setup.

Not flight tested yet, but I'm hoping that apart from looking cool, these lights will actually be useful for relocating lost sight/orientation at extreme distances. I'm not into scale stuff, just everyday sport fun flying.

I'm going to mount the wide angle EPILED LEDs at a tip corner angle so should be visible from front, underside and wings end on, hopefully. They are mega bright even at just 40mA drive current. Very uncomfortable to look directly at in close range. Am wiring the two LEDs in series along with a 22 Ohm resistor for current limiting running off Rx 5V power rail via a mosfet servo switcher gizmo (which I made 25 years ago! It wasn't much use then as even the best LEDs were naff back then)

Thanks also to Freechip and Andy of course.


Last edited by prawlin; Apr 07, 2018 at 09:02 AM.

Quick Reply
Thread Tools