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On 10 Dec 2013 14:04, "Jerome Vuarand" <jerome.vuarand@gmail.com> wrote:
>
> Hi,
>
> 2013/12/10 John Hind <john.hind@zen.co.uk>:
> > This is interesting:
> >
> > http://micropython.org/
> >
> > If only it was Lua! I know there has been some work on this sort of thing (i.e. http://www.eluaproject.net/) but nothing as elegant as this hardware implementation of Python. Just plug it into any USB host computer and edit the scripts as if on a flash drive, whilst a virtual com port gives you a console channel over the same USB.
> >
> > The main issue for these single chip systems is RAM - typically at the highest end you are working with 100-200KiB of RAM and 1-2MiB of Flash. This is plenty for a basic "bare metal" Lua implementation running a test script, but not enough RAM to do really serious work. Problem is there is a huge complexity step between the top end of on-chip RAM and boards with separate RAM chips such as the Raspberry Pi and Beaglebone Black - the RAM interface requires a lot of chip pins reducing the IO availability, and much more complex PCB routing. In practice a large RAM approach only becomes cost effective with very big production runs.
>
> I've been thinking about creating an electronics dev board based on
> Lua for quite some years, but as you say there is a large gap between
> higher end microcontrollers, and low end system-on-chip-s, and stock
> Lua (or Python for that matter) requirements fall just in that gap.
>
> In one direction, going to the next higher device increase complexity
> a lot, since SoCs are so complex it's hard to create firmwares without
> reusing existing operating systems like Linux (if nothing else because
> required drivers need to be so complex). And running Lua on top of a
> Linux quickly reduce the low level capability of such an embedded
> system.
>
> In the other direction, reducing the language requirements, is what
> Micro Python or eLua are trying to do. But not only does that require
> extensive work on the interpreter, it can severly constraint the
> programs running in it.
>
> Recently, triggered in large part by the recent Micro Python
> announcement, I've had a more in-depth look at solutions bridging the
> gap I mention above. Basically I've been looking at an elegant way to
> design an elegant board using a microcontroller (typically a Cortex-M,
> probably a M4F to allow Lua to use floats) and large RAM.
>
> The main problem is that micro-controllers most often only support
> SRAM to simplify the memory controller, and SRAM has relatively poor
> density compared to SDRAM used by SoCs. A typical SDRAM chip can get
> to 32Mbytes [1] (some at $2), while an SRAM one of the same size and
> price range usually tops at 1 or 2Mbytes [2].
>
> However I just found out that there are some micro controllers based
> on a Cortex-M4 of M4F that have an SDRAM controller. Two examples I
> found are the STM32F427xx series from ST [3], and the Tiva TM4C129x
> series from TI [4]. For example a 128 pins Tiva would only use 30 or
> so to access the RAM, leaving plenty of I/O pins for various purposes.
> I think they could be good candidates for a small dev board that you
> can program in Lua, along with a large SDRAM chip, a micro-SD card
> reader and a micro-USB connector.
>
> And if 1 or 2 megabytes is enough, there are plenty of alternatives
> (most Cortex-M-based MCUs have variants with an external SRAM
> controller).
>
> > I realise that Lua was not designed with precisely these priorities, but neither was Python. I'm interested in views of the feasibility of adapting Lua in the same direction that Damian has adapted Python.
>
> I hope you don't mind related views going in another direction :D
The Mizar32 is an option for this as it has 32MB RAM http://simplemachines.it/index.php/modules-menu
> Jérôme.
>
> [1] http://www.digikey.co.uk/product-search/en?pv142=1052&FV=fff40027%2Cfff80434%2C2380053%2C2380057%2C238007c%2C2380083%2C2380084%2C2380085%2C2380087%2C2380088%2C2380089%2C23800e0%2C2380106%2C2380116%2C2380119%2C238011c%2C238011e%2C238012d%2C2380131%2C2380132%2C2380137%2C2380162%2C238016c%2C238016d%2C238016f%2C2380182%2C2380183%2C2380234%2C2380235%2C238023d%2C238023e%2C23802ac%2C2380365%2C2380371%2C2380374%2C238037c%2C2380418%2C238041c%2C2380422%2C2380433%2C2380434%2C2380435%2C2540016%2C26801f7%2C142c00a9&mnonly=0&newproducts=0&ColumnSort=0&page=1&stock=1&quantity=0&ptm=0&fid=0&pageSize=25
> [2] http://www.digikey.co.uk/product-search/en?FV=fff40027%2Cfff80434%2C4002ea%2C401215%2C40353a%2C4037cd%2C2380053%2C2380057%2C238007c%2C2380083%2C2380084%2C2380085%2C2380087%2C2380088%2C2380089%2C23800e0%2C2380106%2C2380116%2C2380119%2C238011c%2C238011e%2C238012d%2C2380131%2C2380132%2C2380137%2C2380162%2C238016c%2C238016d%2C238016f%2C2380182%2C2380183%2C2380234%2C2380235%2C238023d%2C238023e%2C23802ac%2C2380365%2C2380371%2C2380374%2C238037c%2C2380418%2C238041c%2C2380422%2C2380433%2C2380434%2C2380435%2C2540008%2C2540033%2C26801f7&mnonly=0&newproducts=0&ColumnSort=1000011&page=1&stock=1&pbfree=0&rohs=0&quantity=&ptm=0&fid=0&pageSize=25
> [3] http://www.st.com/web/en/catalog/mmc/FM141/SC1169/SS1577/LN1789?icmp=stm32f4pr_pron_p3436s_sep2013
> [4] http://www.ti.com/lsds/ti/microcontroller/tiva_arm_cortex/c_series/tm4c129x_series/overview.page?paramCriteria=no
>