[TenTec] CorsairII obsolescence - MCU copying

[Steve Hunt]

Glenn,

It's possible, but quite difficult.

The processor chip does not allow the code to be accessed directly. As I 
understand it the trick that some have used successfully is to force the 
chip into programming mode, but keep the voltage on the programming pin 
low so that its contents are not changed. At some point in the programme 
cycle the chip does a "Verify" operation. At that stage you cycle every 
byte of the attached memory through all possible 256 values and look to 
detect a slight change in chip timing which would indicate that the 
external value matches the internal value. Once it's complete you have a 
record of the contents.

One guy did it all by hand using laboratory logic analysers; another 
developed a piece of kit which did it in automatically, but it can take 
many hours - possibly several days. I eMailed him offering to supply a 
chip if he were willing to extract the code using his kit. He declined 
saying that the risk of damaging the chip was too high, but offering to 
give advice if I tried to replicate his kit!

At the end of the day, the PIC solution was much easier.

I hate to say it, but another issue could be the availability of the LED 
driver chips. If they were to fail I know that the PIC solution would 
allow me to drive the LEDs directly and eliminate the need for the 
driver board.

73,
Steve G3TXQ


On 12/08/2011 18:31, Glenn wrote:
>   Hi Steve,
>
> Great post and thanks for sharing.
>
> I may have mentioned that I have found a large inventory, 200 pieces, of the original MCU chip in the Corsair II.
> Do you have any experience of pulling the firmware in that chip for a burn into the replacements?
>
>
> Regards and 73,
>
> Glenn WA4AOS
>
>
>
>
>
>
>
>
> -----Original Message-----
> From: Steve Hunt<steve at karinya.net>
> To: Discussion of Ten-Tec Equipment<tentec at contesting.com>
> Sent: Fri, Aug 12, 2011 12:57 pm
> Subject: Re: [TenTec] CorsairII obsolescence - MCU copying
>
>
> Folks,
>
>
>
> I've now added the iambic keyer functionality to my board using a second
>
> PIC. I didn't include the keyer memory functionality because I never use
>
> it, but the connectivity is there if I decide to add it at a later
>
> stage. I've posted the schematics and the object code, plus a rough
>
> layout of the major components, on my web site:
>
>
>
> http://www.karinya.net/g3txq/corsair_display/
>
>
>
> If anyone has a go at building one I'd be very interested in your
>
> experience; in particular:
>
>
>
> 1) Does the simple input circuitry work OK with your levels of HFO signal
>
> 2) Does the board change the number/levels of any spurii heard in the
>
> receiver
>
> 3) Is the board immune to high levels of RF on Tx
>
> 4) Does the "last digit jitter" look about the same as the original
>
>
>
> 5) Does the keyer speed range seem about right
>
> 6) Does the iambic implementation "feel" right. I don't use iambic
>
> myself so it's difficult to judge if it's correct.
>
>
>
> 73,
>
> Steve G3TXQ
>
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