JP1 Remotes

zkidz · Joined: 16 Sep 2011 Posts: 13

I'm wondering if it's possible to get the full contents of flash (including the usually "read only" area) from a JP1.3 S3F8 remote, so I can disassemble it as a learning exercise. The "Raw Download" panel in RM would seem to be the way to do this, but when I click it all I get is "0600:" with no data. I've verified I can download and upload to/from this device by setting a macro, so cabling-wise I should be fine. Any hints?

Also, is there a protocol upgrade that's just a simple PWM executor so I can manually enter some raw codes for experimentation? I'm kind of lost among all the options Smile

Finally, are there linux tools for developing extenders?

vickyg2003 · Posted: Sat Sep 17, 2011 10:43 am Post subject:

Wow you sure are ambitious.

What is a PWM executor?

What remote are you interested in?
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zkidz · Joined: 16 Sep 2011 Posts: 13

The Robman · Posted: Sat Sep 17, 2011 12:58 pm Post subject:

The vast majority of protocols are PWM, with the various NEC protocols being a prime example. But, being PWM doesn't mean you don't have device codes and command codes in there too.
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Barf · Posted: Sun Sep 18, 2011 8:45 am Post subject:

Somewhere I read that protocols like NEC1 (which are varying the length of the gap between the pulses) should not be called pulse width modulation but rather something like gap width modulation. A "real" PWM-signal as used in e.g. automotive engineering (dimming "non dimmable" light sources such as LED being a prime example of its use) typically has a constant period time T and for a "duty cycle" d between 0 and 100% (endpoints sometime excluded) is on for the first d*T/100 time units, and off for the rest. Note that this is typically a signal being continuously transmitted, as opposed to the case of consumer electronic remotes.

A PWM in (extended) IRP-notation (with duty cycle in percent denoted by F) would go something like

{1000k}<>(F p,^100p)+[F:1..99]

zkidz · Joined: 16 Sep 2011 Posts: 13

Well so far I've tried to hack an RDF to get an extra 256 bytes at the beginning of the download by adjusting the base/size and all apparently base-relative addresses (including the checksums), but the data comes back all zeros.

Is the source to libjp12serial.so to be found anywhere public? RM just seems to have binaries.

Barf: you're right, outside of the local dialect here, PWM refers to a continuous periodic signal where the duty cycle is adjusted as a control signal. A prime example is in controlling RC-servos. It is simple to convert a PWM signal into an analog or digital sample on the receiving end, and with 555 timers being cheap, easy to create a control circuit on the sending side. So it's a pretty popular method among the solderers. The CS crowd is less enamored with it, of course, since packets/tokens are much easier to deal with on multitasking OSes.

The correct EE terms for the various protocols are rather diverse. Where the total ON+OFF tie for 1 is the same as 0, one might make an argument for calling those "2-ary Phase-Shift Keying", but not "Bi-Phase modulation" because (I think, based on what I've read so far) both 1s and zeros lead with an ON. The sticking point there is that without bit doubling, you don't have a full period of carrier to speak of. Where 0 and one have different total ON+OFF lengths, one could argue that to be "frequency shift keying" but for the fact that there is a DC component because the ON and OFF durations are not necessarily the same.

Barf · Posted: Sun Sep 18, 2011 1:12 pm Post subject:

zkidz · Joined: 16 Sep 2011 Posts: 13