Will Maple Native run code from external (FSMC) memory?

LeafLabs Garden » Support » Maple Hardware Support

Will Maple Native run code from external (FSMC) memory?

(8 posts) (3 voices)

Started 4 years ago by gbulmer
Latest reply from mbolivar

gbulmer
Moderator

I'd like to know what kind of external memory LeafLabs are planning to put onto Maple Native's Flexible Static Memory Controller (FSMC)?
Is it some form of flash, RAM, or both?

Will it be possible to execute code directly from the external, FSMC attached, memory?
If Maple Native can run code from it, have you an estimate for the performance impact?

Does LeafLabs intend to make it possible to load code straight into the FSMC memory from the IDE, or will that process be command line/Makefile only?

Posted 4 years ago #
mbolivar
LeafLabs

The memory chip on the Native is an ISSI IS62WV5121BLL, 44-pin TSOP type, organized in to 512K 16 bit words. It's a PSRAM chip with a 55ns access time.

The Cortex M3 memory map specifies that the external RAM region (which the FSMC maps the chip into) is executable. However, I don't think I could give you an honest estimate of the performance impact, specifically because I don't know the penalty paid for sacrificing parallel instruction and data fetches.

If we support loading code into the memory chip, we'll definitely fully support it from both the command line and the IDE. It would be nice for RAM builds to be a useful thing again :).

Posted 4 years ago #
gbulmer
Moderator

Great!
We'd like to run a LISP system, so RAM is the best answer :-)

Posted 4 years ago #
mbolivar
LeafLabs

Err, typo: It's an IS62WV51216BLL (note the "6" before the "BLL")

Posted 4 years ago #
kqr2
Member

Now that the Maple Native is available, has anyone tried compiling to external RAM or using it for heap? Is it possible to do this by modifying the linker script?

My code seems to get bigger by the day, so the ability to use off chip RAM seamlessly would be great.

Posted 4 years ago #
mbolivar
LeafLabs

the heap is located on the external SRAM chip by default. no linker script modifications should be necessary.

Posted 4 years ago #
kqr2
Member

Nice. Are statically allocated variables and stack still stored in on-chip ram for faster access?

Posted 4 years ago #
mbolivar
LeafLabs

yes

Update I imagine that since the heap works now, these sorts of questions will be on a lot of people's minds. I've updated the FAQ to cover this: http://leaflabs.com/docs/faq.html#how-can-i-use-malloc-new

Posted 4 years ago #

RSS feed for this topic

Reply

You must log in to post.