topic Re: Can XGATE address external memory? in S12 / MagniV Microcontrollers

Can XGATE address external memory?

AndersJ — Mon, 05 Jan 2009 18:28:46 GMT

Does XGATE have any limitations in how it accesses external memory?

If so, what are the workarounds?

Thanks,

Anders J

Re: Can XGATE address external memory?

kef — Mon, 05 Jan 2009 19:36:54 GMT

Don't know how on S12XE, but S12XD and S12XA XGATE can't access external memory and EEPROM. Only all onchip RAM, whole 2k registers block and 30kB of flash.

Re: Can XGATE address external memory?

HSW — Mon, 05 Jan 2009 21:02:11 GMT

This is also true for S12XE devices. The XGATE's memory map does not contain any external address space.
There are only two ways to let the XGATE access data from an external memory:

Let the CPU12 copy the data into shared RAM space.
Switch into single-chip mode and drive the external memory interface through GPIO. (...but, wouldn't really recommend that )

Re: Can XGATE address external memory?

Fast — Tue, 20 Jan 2009 07:41:15 GMT

Have you tried to reach the port replacement registers such as PORTA and PORTB in emulation modes?

And GPIO is not too bad if you do not often need to change direction and wait for DDR.

Fast