[TI-H] PIXpander hacks
[Prev][Next][Index][Thread]
[TI-H] PIXpander hacks
Yeah, I bet some of you are getting tired of this topic, but I do have some good news. I have all but frozen the schematic design after only 2 revisions. This is actually pretty darn good, although this new design may have problems, which I need to test before I completely freeze the schematic. This news is good because I was prevented from continuing due to the lack of a 74HC125 or 74LS125, which both appear to fit the job, and only cost about a buck. The new connection design for the PIC<->PSX interface uses this chip (which costs as much as a single transistor would) to convert 5V signals to 3.6V and vice versa, doing this to 4 seperate signals, all independantly using the quad 3-state buffer chip.
I am currently finishing up the code that will be used to test the PIC<->PSX connection tonight, will flash the worn-out test PIC tonight, do the testing tomorrow (I forgot to grab some specific resistors that I need, I need some 2.5k-ish resistors, about eight of them for testing) during my electronics class, which is how I have the resources to deal with this problem in depth right now. If the test goes OK, I will report in that it succeeded. Hopefully, if everything goes great, I can get final schematics, part lists, instructions, details on how the sucker really works internally, PIC code/etc. for the first working version online sometime around the 14-17th of this month, around my high school graduation schedule. Sometime after that I will release updated code that will work with a custom protocol, which I allready have an outline and documentation written up on (not exactly good documentation yet) for those who might want to write ASM/C programs for their TI of choice to handle the custom protocol which will allow ASM/C programs/libraries to do the following:
-Get a listing of all variables/data objects stored on the card, including address
-Request a variable/data object by address (Allowing for complete usage of the card, instead of the 16k pieces)
-Send a variable to a specific address
-Send custom data objects (blocks of raw data which can be roughly 64k in size, perfect for game data/etc)
If you want documentation or early schematics (no... Sami's PIC code will not work, the hardware and software of Sami's device has flaws that I could not really fix without starting over), please e-mail me. I personally would like to contribute something worthwhile to the TI Calc community, even if I am just fixing up Sami's idea. Unfortunately, since Z80 Asm isn't fresh in my mind, and I don't have time to research all the TI-8x's Asm variants, I ask for a little help on writing the custom drivers for those that want to use them. The documentation does include tips on how to do memory management of the PSX card/etc, and handling of multi-page cards. I would also like to know if people want to see an add-on schematic to power the 7.2V pin for the card, for those with the hefty cards that run off of it. It will most likely be a Zener/Voltage Regulator deal, but if people can figure it out/etc. I probably won't put the part into the schematic, although a show of hands would help me here too.
Once again, sorry for the prolonging of this thread's death, but hey... TI users might get a new toy... I would like to see the look on a couple friends' faces when I walk into a college course, take notes on my TI and store them away on a PSX memory card for 'safe-keeping'... *grin*.
-Krevinek
_____________________________________________________________
-------------------------------------------------
Matrix-Zed E-Mail (Should This Be Removed?)