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Old Nov 01, 2006, 08:41 PM
Martin - AKA mr.sneezy
PLMS's Avatar
Adelaide, Australia
Joined May 2004
1,678 Posts
Question
PCM 1024 decoder chip out there yet ?

Hi Guys,

Been quite some time since I posted on this forum.
I've been reading the info on other sites about the decoding effort done on the Futaba PCM1024 format. It seems to be more or less complete.

Has anyone done or begun a DIY PIC project (or with other micro) based on this info to make a hybrid PCM receiver out of a cheap common variety receiver (eg GWS etc) and a PIC ?

If so I would be a happy to help with the hardware build and test side of it. I have a bunch of cheapy PPM receivers that could be hacked to add a decoder on the output of the data slicer circuit.

Martin
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Old Nov 02, 2006, 03:27 AM
Ema
Registered User
Joined Nov 2004
5 Posts
Two italian guys (Alessio and Andrea) made a Joystick interface that is able to decode the Futaba PCM 1024 signal.

At this link you can find all documentation (also with sources) about the project:
http://alessioandrea.altervista.org/rcjoyng2.html

Hope this help
Bye
Emanuele
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Old Nov 02, 2006, 09:02 AM
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Belgium, Aalst
Joined Dec 2002
933 Posts
A few years ago I assisted in reverse engineering the PCM protocol. References can be found on my website (http://www.rc-flight.be/electronics.html)

I did it because I had lots of plans, making a PCM receiver form analog ones was one of them. However, I simply do not have the time to do it alone

If you start a project, I would be happy to assist

Frederic
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Old Nov 02, 2006, 04:56 PM
Martin - AKA mr.sneezy
PLMS's Avatar
Adelaide, Australia
Joined May 2004
1,678 Posts
Quote:
Originally Posted by FredericG
If you start a project, I would be happy to assist

Frederic
Hi Frederic, I can do some PIC programming myself but I'm not good enough to write code to interpret the PCM frame. I have been using PicBasicPro for all my PIC projects to date. I think if someone wrote an assembly routine to decode the frame and store the channel variables in RAM registers, I could do the rest in basic (PBP is very good and not slow if done well).

The first step in my mind is to pick a suitable micro. My first thought is the PIC16F628
http://ww1.microchip.com/downloads/e...Doc/40044E.pdf
It's 18 pin so we should be able to get 8 or 10 channels out. It can be run at up to 20Mhz. It's cheap and readily available from most electronic hobbiest suppliers. It also has analogue comparators so could monitor the battery voltage as well and sound an alarm for low battery.
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Old Nov 03, 2006, 01:28 AM
Xtreme Power Systems
Lake Havasu, AZ
Joined Jun 2005
15,784 Posts
A little word of caution... if you expect a good servo output pulse, DON'T use any micro's built-in oscillator. Use an external crystal. I fought this with our XtremeLink and just gave in and used a 16Mhz external oscillator. This gives us +/-10ns stability on the servo pulse.
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Old Nov 03, 2006, 06:14 AM
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Belgium, Aalst
Joined Dec 2002
933 Posts
Spectrum

I do not want to be a killjoy, but lately I am starting to wonder if investing in PCM is still that interesting. There have been many discussions about PCM vs PPM. There are people who believe in PCM, there are people who feel that PCM is worse than PPM. I do not want to open this discussion agian. I have always liked PCM, but now I am wondering if the spectrum technology is perhaps the way to go. I honestly donít know, I know very little about this yet.

There is a very hard real-time requirement of reading the input signal and, more important, generating the signals for the servoís. Several people have started threads about this before, and I believe it us more difficult that one might think. I would think that writing this in assembly could be advisable, while the PCM decoding would be written in a more high level language, especially for a proof-of-concept.


Frederic
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Old Aug 22, 2008, 11:16 PM
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Joined Aug 2008
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pcm 1024 encoding with AVR ATmega16

Quote:
Originally Posted by PLMS
Hi Guys,

Been quite some time since I posted on this forum.
I've been reading the info on other sites about the decoding effort done on the Futaba PCM1024 format. It seems to be more or less complete.

Has anyone done or begun a DIY PIC project (or with other micro) based on this info to make a hybrid PCM receiver out of a cheap common variety receiver (eg GWS etc) and a PIC ?

If so I would be a happy to help with the hardware build and test side of it. I have a bunch of cheapy PPM receivers that could be hacked to add a decoder on the output of the data slicer circuit.

Martin
hello martin
i write a program for atmega 16 (AVR Micro) that read pcm1024 from trainer cord of 9cap(a R/C model of futaba) and send amount of servos to rs232 serial port.
that amount is between 0 to 1023 .
if you want schematic and c program of this please email me
j_sadi63@yahoo.com
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Old Aug 25, 2008, 05:56 PM
Martin - AKA mr.sneezy
PLMS's Avatar
Adelaide, Australia
Joined May 2004
1,678 Posts
Quote:
Originally Posted by j_sadi
hello martin
i write a program for atmega 16 (AVR Micro) that read pcm1024 from trainer cord of 9cap(a R/C model of futaba) and send amount of servos to rs232 serial port.
that amount is between 0 to 1023 .
if you want schematic and c program of this please email me
j_sadi63@yahoo.com
Yes, I'll email you.
Thanks,
Martin
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