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Re: [Paparazzi-devel] Futaba 5 channel radio showing six PPM pulses, not

From: Michel GORRAZ
Subject: Re: [Paparazzi-devel] Futaba 5 channel radio showing six PPM pulses, not seven
Date: Tue, 6 Jan 2009 09:13:37 +0100

The signal i see on your picture isn't the PPM signal you need, it's the RESET generated for the PPM decoder 74VHC164 (probably related with his pin #9)
You must find the right PPM signal : transmitter number of channel + 1 "nice" pulses (try pin #8 of the 74VHC164)


2009/1/6 Paul Cox <address@hidden>

I'm hoping to use a 5 channel futaba radio for paparazzi (Tiny v2.11). I've opened up the receiver and found the PPM input to the shift register. What I'm seeing is six pulses (five associated with the transmitter channels and one sync) instead of the seven that the wiki says I should be expecting ( I have two questions:

1 - Does having six pulses per frame present a problem for the LPC2148 or the airborne code, and what changes to the software may be required?
2 - My pulses look considerably different than the nice square waves I was expecting (see link below for image), so I'm concerned they are not as the Tiny controller expects them. The PPM goes into a standard 8-bit shift register (74VHC164) so is it safe to say that hooking it up to my Tiny will be ok?

Some details of my efforts along with a scope shot of the pulses are available on the wiki at the bottom of the following page:



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