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Altera_Forum's avatar
Altera_Forum
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8 years ago

Passive Serial vs. JTAG programming

I encountered a very puzzling problem. The FPGA code is compiled and downloaded to the Cyclone chip with JTAG, then the Cyclone hardware system is verified to be functional as expected. The same FPGA...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
8 years ago

Are you absolutely sure that it's the same fpga image which is loaded?

There could potentially be a problem with the inclusion of the file in the processor boot image, and you're getting an older version.

Since you have jtag access you could put a constant (e.g. git sha1) into a probe and read it out using jtag in both cases. Then you know for sure it's the same image.

Could the process of downloading get your software into a different software state than when you simply download the image using jtag?

A good place to start would be to check the state of the communication interface using signaltap in the two cases.