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Altera_Forum's avatar
Altera_Forum
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16 years ago

Terasic DE3 JTAG

Hi,

we developed a daughter board for the DE3 board's top connector and forgot to shorten TDI and TDO together. The daughter board itself does not use JTAG.

As a result the FPGA cannot be programmed while the daughter board is plugged in.

My question is how the DE3 decides if a daughter board is plugged in and when to bypass the connector?

Is there a solution without unplugging the daughter board?

Jan

6 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    Read the DE 3 User manual about DIP switches that configure the JTAG chain. There's a bypass switch for each HSTC connector.

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    That's only for the bottom connectors. We need a top connector. I think the only solution is to connect the pins with a wire.

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    Yes, I didn't notice, that the bypass switch is valid for the bottom connector only.

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    short answer: unplug the daughter board when you want to use JTAG. otherwise TDI and TDO _must_ be connected on the daughter board.

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    I can't really unplug, since i need to use signaltap with the daughterboard in use. I used to do that but its simply not an option any longer.

    Wierd thing is that im using alteras own daughterboard "Dual Highspeed AD DA" board, and I simply can't find any way to connect it! The only option i've found so far is getting hold of the SFF connector to disable JTAG (see attatched pic).