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Altera_Forum
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15 years ago

JTAG did not work.

Hello all. We are make PCIe board at Aria GX2. It's highly simplified kit from Altera. The DC/DC is working very good. But JTAGs didn't work at all. I can see signals at JTAG TDI, TMS, TCK but no...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

The JTAG tap controller enables TDO, when it's state advances to a SHIFT_DR or SHIFT_IR state. Never reaching this state (respectively not seeing TDO activated) in standard JTAG scan and similar actions most likely indicates:

- device is held in reset, because one of the supply voltages required for JTAG operation (see the manual for details) is below it's reset threshold

- TMS, TCK or TDO are not connected correctly