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QSPI Initial loading on secondary pinmux

Question asked by Dave Marples on Mar 9, 2019
Latest reply on Mar 15, 2019 by Dave Marples

Oh dear, this one is causing me some trouble!

I still cannot get my MIMXRT1021 QSPI to boot using the secondary pinmux configuration, but I think I understand why....I just don't know how to fix it.

I have BOOT_CFG[3:1]=111b and it is indeed going to the secondary chip at around 30MHz clock, selecting it, writing a read request and waiting for data to come back....trouble is, the data never comes back. The reason for that is that /HOLD (IO3) is low - so as far as the flash is concerned it isn't supposed to respond.  When I look on the 1021EVK (which uses the primary pinmux) /HOLD is high, and the flash reads out correctly. In all other respects the signals appear identical.

 

I have placed external (5K6) pullups on D0..D3 and now I can at least get the processor to read something from the flash, and it responds to erase requests correctly. I didn't see anything about needing external pullups in either the Technical Datasheet or the User Manual, and I can't yet write to the flash properly.

 

Is there any additional data about using the secondary/alternate pinmux or a bit of guidance?  Can't help feeling I'm flying a bit blind here...

Regards

DAVE

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