文件列表:

原理图.pdf (136269, 2007-06-13)
cpld\epm7064.qpf (945, 2007-01-28)
cpld\epm7064.qsf (3087, 2007-01-28)
cpld\jtag_logic.vhd (7234, 2007-01-28)
93lc46配置文件 (0, 2007-06-19)
cpld (0, 2007-06-19)

usb_jtag using FT245BM + CPLD ============================= The jtag_logic.vhd in this directory describes the logic for a parallel-serial converter to be connected to a FT245BM USB chip from FTDI Inc. The newer FT245R, which has the EEPROM AT93C46 for Vendor/Product ID and 6 MHz clock source integrated, could be used as well. Additionally, the FT245R has an option to output 12 MHz from its internal oscillator; that could be used to clock the CPLD (though it would run at half the speed then). _________ | | | AT93C46 | |_________| __|__________ _________ | | | | USB__| FTDI 245BM |__| EPM70*** |__JTAG (B_TDO,B_TDI,B_TMS,B_TCK) |_____________| |_________| __|__________ _|___________ | | | | | 6 MHz XTAL | | 24 MHz Osc. | |_____________| |_____________| The Quartus assignments file epm70***.qsf here lists a possible pin assignment, valid for the PLCC-44 variant of EPM70***. For testing, I just wired a FT245 module (as it is available directly from FTDI and several distributors) directly to an EPM70***, and added only a few external resistors in series with the JTAG I/O pins. I didn't draw detailed schematics yet because the connections can be completely taken from FTDI datasheets. To match the logic voltage levels of my specific target, I chose an EPM70***SLC44-10 with 5V I/O. There are others that use 3.3V etc. For more flexibility, you should add level shifter and some protection circuit on the JTAG I/O. Please note that this CPLD code is NOT the same as in an Altera USB-Blaster, it just behaves very similar. It's very probable that logic of real USB-Blaster performs better than this design. Changes since initial release on 2006-04-23: - added this readme.txt - reorganized my project folder: diff is now created from Subversion repository - explicit state machine encoding to avoid illegal states at powerup - added AS/PS mode Thanks to the readers at edaboard.com for their interest, testing and comments!

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