[Milkymist-devel] SVN Access

[Sébastien Bourdeauducq]

Hi,

On Sunday 09 August 2009 22.12.36 Uwe Bonnes wrote:
> I must admit that my interest is in the LM32 core and not primary in
> Milkymist. On most boards I develop, you find a AVR and an FPGA. The AVR is
> not at it's limits, as it is doing the slow control, but the 5V/3.3V
> interface is one aspect I look for a solution to get rid of the AVR.

You may also want to have a look at AEMB (dual-thread barrel processor with 
the Microblaze ISA) and AE18 (PIC18).
http://www.opencores.org/?do=project&who=aemb
http://www.opencores.org/?do=project&who=ae18

Also, if you only make a basic microcontroller (no SDRAM, no graphics 
accelerators, etc.) compared to Milkymist the resource usage will be cut in 4.

Can we know a little more about your application? :)

> As the board sometimes have long support time requirements, an open
> solution with a strong community baking it would be fine. Joerg's soc-lm32
> seemed fine when I looked at it beginning at 2008, but now development
> seemes stalled.

That's what Milkymist was originally based on actually.

> Also the long times questions stay open in the lattice
> Mico32 forums at
> http://www.latticesemi.com/forums/forum/index.cfm?forumid=101
> didn't enhance the trust in the platform. As now Milkymist switched to
> MICO32, things are getting more interesting again.

From my experience with Mico32:
* HDL design is very good - fast, efficient, well-written and I found no bug 
so far
* GCC has some defects (like crashing or generating corrupt code when you 
compile big programs like a Linux kernel). Not to mention the abominable GNU 
coding style (like files of 10k+ lines containing macros of macros of macros 
of macros of macros of ...  spanning several .h files and tuned by autoconf), 
but this is a problem with every processor, softcore or not.
* GDB has more bugs than a rain forest and is completely unusable as-is

> By the way, could MICO32 run ins some way without external RAM?

Definitely; Mico32 is just a processor core and you are free to implement 
whatever you want in its address space. So you can just map a core that uses 
on-chip SRAM.

> I have a
> ADSP starter board with the XC3SD1800 ( and DDR2 RAM) which has as least
> enough slices.

Depending on your application, you may also want to have a look at Actel 
chips. They are slow and small, but low-power and with some analogue 
interfaces.

Sébastien