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ISP pins with external SDRAM

Question asked by Larry Pelton on Sep 4, 2019
Latest reply on Sep 8, 2019 by Alice_Yang

The ISP boot pins are multiplexed with external bus interface data pins.  I'm having a problem where resetting the chip sporadically results in the LPC54608 getting stuck in the NXP bootloader.  As far as I can tell, the SDRAM pins which are multiplexed with ISP0-ISP2 are high impedance when this happens, because DQML is high.

 

Is this a known problem/error with the boot process?  Disabling entry to ISP using the ISP pins via an OTP memory setting is an option that I've seen listed in another thread, but that doesn't seem like a good solution to me.  Is it possible to reliably use the ISP pins for ISP entry in an LPC54608 design which uses an external memory?

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