Re: [ECOS] RedBoot - RAM Build - Questions

[Andrew Lunn <andrew at lunn dot ch>]

On Tue, Jan 18, 2005 at 02:13:12PM -0800, David Roethig wrote:
> 
> I'm attempting to use RedBoot[RAM] to program flash.
> RedBoot is loaded into RAM via JTAG/GDB.
> 
> 
> Our custom design is using the Sharp LH79520 processor.
> This processor has no internal FLASH and no boot
> loader/monitor.
> 
> The memory layout is:
>    FLASH            4 MBytes
>    RAM (Internal)  32 KBytes
>    RAM (SDRAM)     32 MBytes
> 
> 
> 
> I don't want a resident monitor. We need to use the
> entire flash for application/data.
>
> By reading the documentation and examples,
> I have the impression that the idea behind RedBoot is
> that it is a resident monitor. Is this correct?

It can be used this way. It can provide the stubs gdb uses so that you
can debug your applications. 
 
 
> Is the FIS necessary for just downloading code into flash?

You need some of it. The FIS commands give you the option to write to
flash etc. But if you have a jtag interface etc, you can use that
instead. Redboot can jump into code in FLASH, so if you have a ROM or
a ROMRAM application you could use RedBoot to start it and not need
FIS.

> Ideally, RedBoot should fit into 32K internal RAM because
> the external SDRAM requires setup. Would it be possible
> to slim-down RedBoot to this size?

Could be. Take a look at your configuration. There will be lots of
CYG???_BUILD_REBOOT_WITH_* options. Disable all the ones you dont need
to reduce the image size.

The other option is to not use RedBoot at all. Write a ROM or a ROMRAM
application which takes control of the system right from startup.  

You might want to think about having a different development system
than your final product. Your development system might have extra
flash/RAM so that you can have all the extra easy of using
RedBoot. Your final product uses a ROM or a ROMRAM application without
RedBoot.
 
        Andrew 

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