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Altera_Forum's avatar
Altera_Forum
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17 years ago

can't scan jtag chain in customer built board

I have a custom built board with EPM570T100C3N, this is the only programmable device in the board. The other chip is a CY68013A. The USB part of the board works well, but the CPLD cannot programmed b...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
17 years ago

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It's pin-by-pin identical to a EPM570T100 production circuit, that I designed. Did you also verify the correct pin numbering (and mounting position) of the TQFP100 package?

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I found one of the problem, a 10K Ohm resistor（R6 in schem) was misreplaced by a 1Kohm resisitor. After use the right value resistor, Quartus successfully recognize the CPLD. But in most of the time, the programming will failed during the "programming device" period after blank checking.

The length of tracks (TCK/TMS/TDI/TDO) are approx. 35mm. Are those tracks too long ?