Hi everyone, I'm new here

I want to know if it's possible to program At91SAM7x256 without need to
use a JTAG connector and cable.

Thanks

You can program it over USB with the SAM-BA bootloader. See
http://www.atmel.com/dyn/products/tools_card.asp?t... for more
information.

thank you for help
I want to ask if it's a good practice to port linux on this MCU

Akrmi Yaacoub wrote:
> I want to ask if it's a good practice to port linux on this MCU

It is an ARM7 part so has no MMU.  There are distributions of Linux that
will run without an MMU (uClinux for example), but just because you can,
does not mean you would want to.  Lack of memory protection removes one
major advantage of using Linux.

Also no usable Linux distribution will run in the on-chip memory
resources; you'll need a board with external RAM and unless you boot
from removable media, external Flash too.

If you need hard real-time performance and small memory footprint, Linux
would not be appropriate.  If you want to take advantage of
communications devices and storage media of various types Linux may be a
good choice.

Consider something more suited to small devices such as eCos if you need
real-time and extensive device support, or FreeRTOS is you simply need a
real-time preemptive priority based scheduler.

Clifford

I agree, this is not the kind of controller that you would run Linux on.
If you are interested in playing with Linux on an ARM controller, use
one of the bigger ARM9 parts with a MMU, like the SAM9 series. But in
any case you will need external Flash and RAM and a whole lot of
infrastructure, so it's best to start with a board that already comes
with a working Linux distribution, otherwise you may be soon get
frustrated.

My application needs an I/O (LCD, SD, GSM via rs232) management with a
soft real time performance and not a lot of data to store on memory.


I know that it's not necessary to make it with embedded linux kernel
But I want to do so to familiarise with embedded linux.

Do you advise me to switch to an ARM9 MCU if so can you, please,
recommand me a low cost board that have these features?

Kind regards

How much is "low cost"?  To run Linux sensibly you need probably an ARM9
at 200MHz with >=16Mb external RAM and >=4Mb of Flash.  That is just teh
requirement to get the OS to run.  Linux is a general purpose OS, if
your application is very specific and small, you will be spending more
on hardware to support the OS than is strictly necessary to implement
the application.

I suggest then that you simple Google "ARM9 development board" if you
still think you need this.  I think eCOS may be more appropriate
however.

oresama wrote:

> and what about distributions like RTLinux can it run inside an MCU with
> an MPU but not MMU?
>
You are really stuck on this Linux thing aren't you!?  That is a
question probably best answered by checking out the project's own web
site.

RTLinux however has even more complex requirements that regular Linux.
Despite its name it is not in fact a Linux distribution, it is a VM that
runs a real-time micro-kernel with Linux as a virtualised guest OS.  So
not a chance on an ARM7 IMO.