PPM Decoder Chip: any off-the-shelf ones?

[CraigF]

Just wondering if there are any I can easily get in small quantities. Maybe some hobbiest sells pre-programmed PICs etc.? Thanks.

[Mr.RC-CAM]

Use a CD4015 or CD4017 shift regsiter. Cheap, and most legacy R/C Rx designs use them.

RC-CAM

[Dan Baldwin]

The only reasons I can think of to use a PIC for a PPM decoder is that you could have no external components, just send the output of the discriminator/detector to it, and you could use a smaller chip; 8 pins for up to 5 channels, 14 pins for 8 channels instead of the 16 pins of a 4015 or 4017. On the other hand, a 4015 or 4017 will be more accurate without the jitter that you would get with a microcontroller.

Dan

[XJet]

Don't forget the very important advantages you can get from performing some testing on the pulsetrain coming out of the receiver -- like FMA and Berg do with their microcontroller-based decoders.

This allows you to do cool stuff like auto-sense the transmitter shift, ignore pulses that are obviously in the wrong place or an invalid width (thus reducing the effect of interference) and add a failsafe capability.

Using a microcontroller-based decoder can turn a good receiver into a great receiver.

Bruce Abbot (sp?) has even been kind enough to publish his PIC-based decoder for those who want to copy it -- so you won't have to reinvent the wheel.

[Dan Baldwin]

I stand corrected. Heres a link to Bruce Abbott's source code for the 12c508 and 12f675.
http://homepages.paradise.net.nz/bhabbott/decoder/rxdecode.asm

Dan

[chaitanya]

Or you can buy some programmned PICs here,
http://members.dodo.net.au/~daviddewit
-chaitanya

[ilufa]

Don't forget the very important advantages you can get from performing some testing on the pulsetrain coming out of the receiver --

Another advantages is you can mix the signals, e.g. for dleta wing & V-tail :rolleyes:

[CraigF]

Thanks for the ideas guys. I kind of like the idea that I can "do things" with a micro. I don't have a PIC programmer, but some others, and I'm playing with Atmel these days. So I suppose I could translate the logic, for my amusement.