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Altera_Forum's avatar
Altera_Forum
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14 years ago

Is there a way to slow down the USB Blaster Cable operation?

To improve the reliability...

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    14 years ago

    Hi,

    I had some similar issues with the JTAG interface on an older board not being routed "as it should", ending in noise and failures with the high-speed USB Blaster. The JTAG operated well with the slower one Byteblaster MV. My question on slowing down the USB Blaster was neglected - no way to adjust speed...

    But... who knows, some years have past since my request..
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    14 years ago

    In my case, the JTAG is routing is very short, less than 15mm in length, good GND and DC connection, but still there ate some problems with SignalTap.

    More than that - it behaves slightly different with different versions of Quartus II...

    Sometime in the past i had read about different driver, substitute to the Altera one, but i can't find it on the net now...
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    14 years ago

    JTAG signal quality issues aren't particularly related to the involved JTAG clock speed of 6 MHz, which isn't very high actually, rather than the transmission of the TCK signal. In some cases, ringing edges generate double clocking and respective protocol failure. Also crosstalk from fast on-board signals can cause trouble.