Catnip Cable : will you buy one ?

[The_Laird]

A poll has to have choices . . . .

[Zerosquare]

Interesting.

 

Couple more questions. You are using a USB to 232 chip from what I gather. Are you using this for interfacing to your CF board, and supporting connecting to joypad 2 for BJL transfers?

There are two connection modes available.

 

When connected to the JagCF, the Catnip acts basically as a USB-to-RS232 converter, at up to 3 Mbauds (the JagCF has an internal, high-speed UART). The protocol has not been defined yet, but it won't be based on BJL. Uploading programs this way is mainly intended for developers (debug features will also be accessible). For "standard" users, it will be easier to copy the software they want to run on a CF, using their computer.

 

When connected to joypad port 2, the Catnip emulates a parallel BJL cable. This is done through an internal ATtiny2313 microcontroller, which gets its data from the FT232R chip, and handles the BJL protocol (using a standard USB-to-parallel chip directly would have been too slow, as BJL requires constant synchronization between the Jag and the computer, and USB is not optimized for transferring little blocks of data ; it also avoids the sync problems of the parallel cable on modern machines).

 

(OK, I lied. There are three modes in fact, as the microcontroller can also be used to update the JagCF's FPGA )

 

I've also included a bootloader in the microcontroller, so that the firmware can be updated through USB to fix bugs, add new protocols and features, etc.

 

If it does the latter (which I think it does) are you supporting 4 bit transfers or 8 bit transfers?

Both , as well as the commands needed to auto-select the upload mode, reset the Jag, read/write the cartridge EEPROM, etc.

Debug features (registers and memory dump, etc.) work also, but very slowly due to unfortunate timing requirement in the protocol.

 

I am not familiar with that FTDI chip (although I have used one of their chips on my OS X machine for a USB to serial interface for a couple devices non-jaguar).

If you know the FT232BM, the FT232R is basically the same chip with fewer peripheral parts needed, and a few new features.

 

Just curious on how you implemented this. Sounds interesting.

Thanks for the interest. Edited November 10, 2006 by Zerosquare

[Zerosquare]

A poll has to have choices . . . .

http://www.atariage.com/forums/index.php?s...t&p=1123735

[belboz]

Thanks for the info.. Sounds like a sensible approach for a USB-BJL interface, and enabling your higher speed serial modes for the CF.