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finally i have understood the reason why my usb-jtag-cable is not working with my flex10K board: the problem is related to the jtag chain in where the jtag connector has been wired as "the last device in the chain", and this is terribly wrong !!!
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I think the Altera UP1/UP2/UP3 boards have a connection like this, so you can daisy chain boards. However, they have two JTAG connectors, one for the USB-Blaster (or ByteBlaster at the time they were created) and then another for the daisy chain. Does your board have two JTAG connectors?
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The byteblaster is the first device in the chain and his-244-chip is propagating signals through the jtag wires to the fpga chip, to the eeprom configuration chip (it's an optional, not soldered on my devboard but you can add it), and finally to the jtag connector on where you could plug a cable to connect other jtag device on the jtag chain.
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Ah, I see, so rather than having two 10-pin JTAG connectors on this board, they have the ByteBlaster built in. In that case, just build an adapter board to wire the signals from your USB-Blaster into the parallel port pins.
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It has no sense for me! A jtag connector to add external device ? what is the meaning of that ?
No sense, but it makes terribly wrong the wiring i did putting the jtag connector of my usb-jtag-cable on it because TDO and TDI can't be propagated in right way.
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Right, and the TCK and TMS signals would also be the wrong way.
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I really think the final solution is: i have to make a new dev-board putting a PLCC84 socket on a 1000-holes-pcb, putting a flex10k inside it, adding a 50Mhz 4-pin oscillator clock on the clk43 pin of the fpga, and wire the fpga jtag (TDI, TDO, TMS, TCK) signals the the usb-jtag-connector, then installing Quartus-II V8 and have fun with it.
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I'd create a USB-Blaster to ByteBlaster cable adapter. It won't take very long. Get a DB25 connector and a 10-pin header, and wire them up.
Cheers,
Dave
Honored Contributor
