12CH 3-way PPM mixer - Page 6 - RC Groups
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Oct 30, 2010, 08:02 PM
fast
fmkit's Avatar
I've learned that many controllers put out PPM way above 5v,
input voltage higher than supply line shorted via built-in diodes and yes, the chip will get hot.
As far short on output pin - it's safe, there are internal resistance of 27 OHm .
Single shorted pin won't make much heat and won't cause supply line to puul down.
Without seeing wiring/ o-scope diagram I'feel helpless, PPM is all about logic levels (simple), as lomg as input signal is under 1.3v(low logic) and above 1.3v (high ==1) and below supply voltage the mixer must work.

If the circuit left hanging next to powerful booster chances are it won't work without shield and coaxed signal lines. Friend of mine turned on 7W TLRS booster near LI-PO charger and it went smoking purely because of RF radiated into charger circuit, wired mixer gets even stronger EMI.
@ LICHI : PM your address I send another chip.
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Oct 31, 2010, 07:25 AM
Registered User
Hugeone's Avatar
FM,

I'm trying the mixer with PCtx and trackR2, so far the PCtx work.
The TrackR2 channels follow the PCtx's 1-9, but it's glitchy. Looking with the scope I see the channels 10-11 coming back to 1.5ms for split-second. Like if the mixer was not accepting the signal and coming back to buttons. Also, if I leave the trackr2 without moving the mixer will permanently select the buttons. The trackR2 signal is 0-2.5V (pulled down 400ohms) and clean. I tried 10K, 1K or no pull down, problem is the same. 2ch B input limit or no don't change anything either.
Last edited by Hugeone; Oct 31, 2010 at 03:21 PM.
Nov 08, 2010, 08:45 AM
Registered User
Moose2's Avatar
I have the following equip:
9C
Dragon Link
TrackR1 rev. 2.1

I need 10 channels.
I only want to use the ppm mixer with the head tracker.
Has anyone installed one of these PPM mixers in a 9C and could you post some installation pics?
Has anyone had success using it with the DL yet?
Has anyone used it with a TrackR1?

Last, does the mixer come with some better instructions than what is shown on the website? I assume "buttons" are switches but what exactly is a "port"? Does it require 1 or 2 buttons? Am I correct that the buttons wouldn't need to be hard wired (could have one switch that could be plugged into either circuit as needed)?

Thanks in advance
Nov 08, 2010, 09:12 AM
Registered User
Hugeone's Avatar
"Port" are PPM input, buttons are optional.

So far, I never heard of sucess with that mixer. I have 4 of them here and not one will take ppm stream to port B form either trackR2 or from another mixer's output.
Nov 12, 2010, 05:11 PM
Registered User
mr..speed's Avatar
Quote:
Originally Posted by Moose2
I have the following equip:
9C
Dragon Link
TrackR1 rev. 2.1

I need 10 channels.
I only want to use the ppm mixer with the head tracker.
Has anyone installed one of these PPM mixers in a 9C and could you post some installation pics?
Has anyone had success using it with the DL yet?
Has anyone used it with a TrackR1?

Last, does the mixer come with some better instructions than what is shown on the website? I assume "buttons" are switches but what exactly is a "port"? Does it require 1 or 2 buttons? Am I correct that the buttons wouldn't need to be hard wired (could have one switch that could be plugged into either circuit as needed)?

Thanks in advance
Search back for my posts. I got it running but don't use it at the moment because my system changed.
Nov 29, 2010, 07:09 PM
Registered User
Nestor Vald's Avatar

In France ?


Hi Peter, could you please tell me if you can send your little plate un France ?

Thanx in advance.
Nov 29, 2010, 07:28 PM
Praying for better weather
Coyote64's Avatar
Quote:
Originally Posted by lichy
well, i'm afraid its got nothing to do with my uhf system..
Yeah i know that, but your trying to get it working / fixed so it does work. This mixer wont work with a UHF system so whats the point ?
Jan 10, 2011, 07:44 PM
fast
fmkit's Avatar
I've re-worked ppm mixer,
output resolution is 255-512 (was 100-200)
input ppm sampled and output at 512 that is native Wii Nunchuck resolution

at startup the mixer is trying to read Nunchuck and if not found within 0.5s the the pins (SDA/SCL) used as on/off channels added to input ppm
if there is nunchuck you can program 3 to 12ch frame, set constant sinc or constant frame rate, set body box mode or just use nunchuck standalone.
settings changed the same way as in RF Beacon, codes entered as X.X - to separate digits pause for 1-3s and 4s inactivity ,
example:
4.3 == reverse ch3,
1.2 == 1st 2channels input ppm added to nunchuck channels,
2.3 == use only 3 ch. generated by nunchuck(added to input ppm)

anyone wanting special mode ? I'll program what seem useful
Jan 10, 2011, 07:55 PM
fast
fmkit's Avatar
I've just tested two mixers in series, one is feeding another one.
the mixer chip adds no latency, input pulses placed into output buffer without waiting for complete frame
Jan 11, 2011, 01:33 PM
Registered User
Nestor Vald's Avatar
Wow great news and good job Peter.
I hope you could now send its to France if you have some ;O))

Nestor.
Jan 13, 2011, 03:41 AM
Up up and away!
FpvKiwi's Avatar
Hi fmkit! I'm a fan of your work and read much of what you wrote here.
Nice to see that you're still working on the ppm mixer. I saw that you had some problem with DL / Scherrer LRS. I'm looking into this as well at the moment and just posted some findings. Let me know if I can be of assistance.
Jan 13, 2011, 12:10 PM
fast
fmkit's Avatar
FpvKiwi, if you wait for incoming frame to complete by the time you output mixed channels added latency become annoying.
In last version ppm mixer input pulses placed into output buffer without delay , worked smooth with pc sim (realflight) but for some reason had glitches with TLRS probably because of frames longer than 28ms.

In new version mixer user can set constant frame rate or constant sinc as well number of channels in output frame (1-16) and ppm polarity, also incoming channels forced to 1ms-2ms, that is if incoming pulse stretched to 2.4ms it will output as 2ms and 0.5ms as 1ms, this way output is always predictable.
Now channels sampled at 512step. I've also added master/slave mode, if set 1st four channels from slave ppm source replaced with master ppm if aileronor elevator sticks moved off center. Tomorrow will ship 1st nunchuck w/built in mixer, it works absolutely smooth and as fast as you configure it.
Jan 13, 2011, 12:52 PM
Up up and away!
FpvKiwi's Avatar
Ok, sounds like the new version would work better with TLRS. Modifying the PPM stream as you describe without incurring any delay sounds like quite some thought work!
When you say sampled at 512 steps, what does that mean? 512 steps within the range 1-2ms (= 2us per step) or in the range 0-2ms? Just curious.

Clever thing about the master/slave mode.
Feb 04, 2011, 07:30 AM
fast
fmkit's Avatar

new version ready


the mixer was much imroved,
now user can set any number of output channels, choose constant frame rate of 25.5ms, or constant sinc rate of 5.5ms and output polarity
most imoprtant all channels now fixed at user programmed offset
(in old version if there was glitch in ports A/B all remaining channels were shifted up and down).

FpvKiwi: channels output 256 to 511, that is 256 true steps.
Feb 11, 2011, 03:52 PM
Registered User
Hugeone's Avatar
I just received the new mixers, I tested them with my 12Z and I got a 36ms frame rate, what's wrong?


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