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Altera_Forum
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8 years ago

MAX10 Dual Purpose/JTAG issues

I am using an M08 device and trying to set up dual mode pins. I enabled JTAG pin sharing and disabled nCONFIG, nSTATUS... I only needed two pins for my user mode (TCK and TMS), but I also added...
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Altera_Forum
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8 years ago

This doesn't sound right to me. Everything you describe sounds appropriate. I don't think you're suffering from anything dual-purpose pin related. If JTAGEN is high then, regardless of the JTAG pin sharing setting, you should be able to access the device via JTAG.

Can you confirm that the JTAGEN pin is indeed high? Can you measure it? I appreciate you have a pull-up but I think something untoward is going on.

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When I cycle power (re-loading the old, non dual use code), the JTAG recognizes the device again

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So you have something programmed into the CFM - right? Can you erase the FPGA's internal memory and work with a blank device?

I'm concerned that the design in CFM is causing the problem, perhaps with the power rails. If a rail is dipping, due to excessive load, then the JTAG is likely to break.

Cheers,

Alex