[TI-H] Re: PIXpander source

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[TI-H] Re: PIXpander source



Hi,

The source code of the PIC program is now available on my page.

I have used the (obsolete) PASM assembler from Parallax. To compile
the file with MPLAB from Microchip you need to use a special header
that contains all the definitions of the directives; Search the
net for this file.

In the source you can also see how the variable-transfer is done
between the PIC and the calculator.

I hope that many of you will be able to detect bugs in the code or
give me some ideas to implement.

Regards,

Sami Khawam 

http://sami.ticalc.org


On Mon, 4 Jun 2001, Sami Khawam wrote:

> 
> 
> I am resending this message, since the first time I sent it
> I was not yet subscribed to the list; I am not sure if it
> arrived:
> 
> 
> Hi all,
> 
> I have just finished my course and now I have some free time to
> continue the work on ti-calc stuff. I haven't had the time yet to
> read all the messages on this list concerning the PIXpand.
> 
> Adam Thayer and Stephan Effelsberg: I have just read the emails you
> sent a while ago (more than a month); Sorry for not being able
> to answer you sooner...
> 
> I saw Stephan's commented de-asm; I suppose that the first thing I have
> to do now it to release the original source code to make it easier to
> debug.
> 
> Also, could you please list all the points you think are wrong in the
> hardware? Here are some of the answers to the points I have found in
> Adam's messages:
> 
> -The 5V->3.xV conversion is implemented with the 120/330 resistors and the
>  3.3V zener on the power line only. I dont think that we need to add
>  conversion to every input pin of the PSX card, since they should be
>  5V tolerant.
> 
> -Adam: You are right about the fact that ACK is supposed to be open-drain
>  the that there is no pull-up resistor on it like the one on the DAT line.
>  However, when experimenting with the device I have found that removing
>  the pull-up resistor from ACK created better results (haven't investigated
>  on the reasons for this). Anyway, in the beta code the ACK line is not checked
>  as it should be (you will see this in the source code soon).
>  
> -Adam: Yes, Pin 1 of the 2.5mm jack is not like pin 2, this is made so to
>  save a pin on the PIC. The open-drain line on pin 1 is implemented in software.
>  The same thing could be done with pin 2 and save the diode.
>   
> 
> Again, this is a beta version and I know that it has many bugs (however, I was
> able to succefully transfer a variable with it).
> 
> 
> Regards,
> 
> Sami Khawam
> http://sami.ticalc.org
> 
> PS. In the archive on ticalc.org I was only able to read the messages sent
>     during May; Thus I dont know if Adam has released his version yet.
> 
>
References: