ISP pins with external SDRAM

[lpelton]

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?

[Alice_Yang]

Hello  Larry Pelton ,

I think you'd better disable ISP, or it is easy to enter ISP mode when the pins are multiplexed.

Have a great day,
TIC

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