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Altera_Forum
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13 years ago

Cyclone IV E JTAG issues - VCCA voltage level

Hi all, I have a custom board with Cyclone IV E (EP4CE115-F484). I am trying to access it via JTAG from Quartus, but keep receiving the "Error: Can't access JTAG chain". I check the Quar...
Altera_Forum's avatar
Altera_Forum
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13 years ago

Hi,

well - if there is only TDI and a pull-up on this Pin and the pin did some pulses initially, even being incorrectly driven with TCK in your first wiring, this TDI perm. low seems strange as both pins are driven by same "output power" from the BB point of view...)...

If the TDI pin is low as soon as the Cyclone is powered this indicates more or less that either the pull-up is missing or the device itself has a short on the input when being under bias. Second is less repairable :-/