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    FX3 doesn't try to boot from SPI flash


      Hi all,


      I have an issue with FX3 booting from SPI flash. We have a custom design that supports booting from both USB and SPI. We have a jumper circuit that configure PMODE so that with jumper on, FX3 boots from USB, otherwise it boots from SPI. We have tested that booting from USB works with the jumper on. We also confirmed USB Control Center can successfully program SPI flash. Meanwhile I saw the activities on SPI bus. This verifies the connection from FX3 to SPI flash is good.


      But with jumper off, it doesn't boot from SPI, after pressing reset button. In fact, I saw no SPI activity on the scope, so it doesn't even try to boot from SPI. Below is what I did to troubleshoot:

           -  checked the PMODE[2:0] to be "0F1", as expected. Voltmeter reads 0 and 1.8V for PMODE[2] and PMODE[0]. PMODE[1] reads 0V but has large impedance to ground. So I believe PMODE[1] is floating.

           -  probe the SPI SCK/CS signals on scope after pressing reset button (works for USB boot), no SPI activity was seen.

           -  checked that all voltage supplies are correct: VIO[1-5]=1.8V, CVDDQ=1.8V, VDD=1.2V, VBATT=3.3V

           -  checked that 19.2MHz clock is good.


      Any idea where I might be missing? Thank you in advance.




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