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'Help 16c54a and Sp5055s'
1999\06\23@221442 by Michael C. Sullivan

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I have a 2.4ghz transmitter and matching receiver that freq's are set by
using a 16c54a and a SP5055s... Here's the problem..the steps are
2400,2427,2454,2481---27mhz jumps...I need to program the pic to change
this to much smaller differences...The pic I have is code protected and
I can't figure out how they programmed it.. THE PRIZE..I will supply
schematics of the hook up to anyone that thinks they can do this and I
will give you the neatest 2.4ghz trans and receiver combo around if you
can solve the problem...Each unit has 1 video channel and 2 audio
channels...very high power output in a small package...Hmmmm who could
we watch with this???   Mike

1999\06\23@223523 by Dennis Plunkett

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At 18:45 23/06/99 -0700, you wrote:
>I have a 2.4ghz transmitter and matching receiver that freq's are set by
>using a 16c54a and a SP5055s... Here's the problem..the steps are
>2400,2427,2454,2481---27mhz jumps...I need to program the pic to change
>this to much smaller differences...The pic I have is code protected and
>I can't figure out how they programmed it.. THE PRIZE..I will supply
>schematics of the hook up to anyone that thinks they can do this and I
>will give you the neatest 2.4ghz trans and receiver combo around if you
>can solve the problem...Each unit has 1 video channel and 2 audio
>channels...very high power output in a small package...Hmmmm who could
>we watch with this???   Mike
>
>

These are simple PLLS you can get the imformation on the AMRC values to be
placed into the PLL from the data sheets, you will need to know the
reference frequency and the current divide values (Simple to measure and
calculate). The you will have to see if the PIC is controlling the power
stage bias with the aid of a lock signal and some other goddies. This is
quite simple code to create and can be done in about a day or so. So there
is not a real need to recover the codee from the PIC, just need the circuit.

Have fun

Dennis

1999\06\23@225706 by Henry Carl Ott

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At 06:45 PM 6/23/99, you wrote:
>I have a 2.4ghz transmitter and matching receiver that freq's are set by
>using a 16c54a and a SP5055s... Here's the problem..the steps are
>2400,2427,2454,2481---27mhz jumps...I need to program the pic to change
>this to much smaller differences...The pic I have is code protected and
>I can't figure out how they programmed it.. THE PRIZE..I will supply
>schematics of the hook up to anyone that thinks they can do this and I
>will give you the neatest 2.4ghz trans and receiver combo around if you
>can solve the problem...Each unit has 1 video channel and 2 audio
>channels...very high power output in a small package...Hmmmm who could
>we watch with this???   Mike


Been there, done that. Just last week as a matter of fact.

I've just been mucking around with the receiver module.
So far I've got a keypad, a 16f84, and a two line lcd display. Direct
freq. entry via keypad. Effective receive range is from about 2.25 ghz to
about 2.8 ghz (after that, the vco goes out of lock). Minimum frequency
resolution of 125khz. I was about to add a scan function tied to the rssi
output, but started running out of i/o pins. I've got a work around for
that, I've just have not gotten around to adding it (hint: the sp5055 has
some unused i/o pins).

I'm not sure where I'm going with this project. It might be a marketable
product or it might just be something that I post on my web site.
It's too early to tell yet, so I'm not giving any code away yet.

However....
I assume these are the same units that Mat-Co is selling (or some wave-com
variant)?
It's really not all that difficult.
Download the data sheet for the SP5055, all the information you need is
there. Just some basic I2C routines and a little bit of math.
I'll even give away a big piece of the puzzle.
The actual receive frequency = ((divider value * 125,000hz) + 479,500,000hz)

If you have any specific questions, fire away.
 Or if you just want one to play around with, maybe we can work something out.



carl

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Henry Carl Ott   N2RVQ    spam_OUTcarlottTakeThisOuTspaminterport.net
http://www.interport.net/~carlott/
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You're entitled to your own opinions.
You are not entitled to your own facts.

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