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This is a group for folks designing and programming embedded systems using the Rabbit Semiconductor C-programmable microcontroller. This group is not affiliated with either Rabbit or Z-World, but is a user forum for sharing ideas, asking questions, flaunting knowledge, and other typical user group stuff. The Rabbit is a powerful uC, supported by a full-featured C-compiler.
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RCM3900/RCM3910 memory map - Ian Lovatt - Aug 7 11:02:51 2012
We are designing a board based on the RCM3910 module and have a question
regarding memory configuration. Any help with this would be greatly
appreciated.
As we understand the RCM3900/RCM3910 can be run at high speed (44MHz) with program code copied from flash to a fast SRAM chip at boot time or without the clock doubler and execute code directly out of flash. When operating in high speed mode it looks like the bios sets up memory quadrants with only 256k of the normal RAM (which is 512k in total) accessible. It looks like it would require us to alter the bios ourselves if we wanted to make ALL the 'normal' RAM available whilst executing at 44MHz ie. No flash mapped in- 2 quadrants mapped to program code in 'fast' SRAM and the other 2 mapped to normal RAM.
Can anyone confirm this? Has anyone had any experience in making this modification or customising the rabbit bios libs in general?
Cheers,
Ian
Ian Lovatt
Embedded Software Engineer
t-mac Technologies
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t-mac Technologies Ltd
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As we understand the RCM3900/RCM3910 can be run at high speed (44MHz) with program code copied from flash to a fast SRAM chip at boot time or without the clock doubler and execute code directly out of flash. When operating in high speed mode it looks like the bios sets up memory quadrants with only 256k of the normal RAM (which is 512k in total) accessible. It looks like it would require us to alter the bios ourselves if we wanted to make ALL the 'normal' RAM available whilst executing at 44MHz ie. No flash mapped in- 2 quadrants mapped to program code in 'fast' SRAM and the other 2 mapped to normal RAM.
Can anyone confirm this? Has anyone had any experience in making this modification or customising the rabbit bios libs in general?
Cheers,
Ian
Ian Lovatt
Embedded Software Engineer
t-mac Technologies
[cid:image001.jpg@01CD74AA.C3085D20]
t-mac Technologies Ltd
Stand Park, Sheffield Road, Chesterfield, Derbyshire, S41 8JT
T. +44 (0)844 287 0007 F. +44 (0)844 287 0006
Technical Support. +44 (0)203 322 3001
E. i...@t-mac.co.uk
B. blog.t-mac.co.uk/<http://blog.t-mac.co.uk/>
________________________________
www.t-mac.co.uk<http://www.t-mac.co.uk/> Monitor, Meter, Manage, Control. BMS & Energy Management.
Telephone: 0844 287 0007 (International +44 (0)1246 233 632)
Support: 0203 322 3001 (International +44 (0) 203 322 3001 )
Fax: 0844 287 0006 (International +44 (0)1246 201193)
Please consider the environment before printing this email message.
This message contains confidential information and is intended only for r.... If you are not r... you should not disseminate, distribute or copy this e-mail. Please notify s...@t-mac.co.uk
t-mac Technologies Ltd. Registered in England. Company No 5254756. Stand Park. Sheffield Road. Chesterfield. S41 8JT.
(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )
Re: RCM3900/RCM3910 memory map - Scott Henion - Aug 7 11:31:28 2012
On 8/7/2012 10:06 AM, Ian Lovatt wrote:
>
> We are designing a board based on the RCM3910 module and have a
> question regarding memory configuration. Any help with this would be
> greatly appreciated.
>
>
>
> As we understand the RCM3900/RCM3910 can be run at high speed (44MHz)
> with program code copied from flash to a fast SRAM chip at boot time
> or without the clock doubler and execute code directly out of flash.
> When operating in high speed mode it looks like the bios sets up
> memory quadrants with only 256k of the normal RAM (which is 512k in
> total) accessible. It looks like it would require us to alter the bios
> ourselves if we wanted to make ALL the 'normal' RAM available whilst
> executing at 44MHz ie. No flash mapped in- 2 quadrants mapped to
> program code in 'fast' SRAM and the other 2 mapped to normal RAM.
>
> Can anyone confirm this? Has anyone had any experience in making this
> modification or customising the rabbit bios libs in general?
>
The RCM3900 (and 33xx, 32xx modules) have 768k of RAM. 512k of fast RAM
and 256k of battery-backed RAM.
The bios copies the flash to fast RAM and maps it to the lower 512k, The
battery-backed RAM is mapped at the 512k address (0x80000). The upper
256k is mapped to flash so it can access the user and ID block.
So, all the RAM is available. xmem should be available from the end of
your code in fast RAM to the top of the bbram.
--
------
Scott G. Henion, Consultant
Web site: http://SHDesigns.org
------
(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )
>
> We are designing a board based on the RCM3910 module and have a
> question regarding memory configuration. Any help with this would be
> greatly appreciated.
>
>
>
> As we understand the RCM3900/RCM3910 can be run at high speed (44MHz)
> with program code copied from flash to a fast SRAM chip at boot time
> or without the clock doubler and execute code directly out of flash.
> When operating in high speed mode it looks like the bios sets up
> memory quadrants with only 256k of the normal RAM (which is 512k in
> total) accessible. It looks like it would require us to alter the bios
> ourselves if we wanted to make ALL the 'normal' RAM available whilst
> executing at 44MHz ie. No flash mapped in- 2 quadrants mapped to
> program code in 'fast' SRAM and the other 2 mapped to normal RAM.
>
> Can anyone confirm this? Has anyone had any experience in making this
> modification or customising the rabbit bios libs in general?
>
The RCM3900 (and 33xx, 32xx modules) have 768k of RAM. 512k of fast RAM
and 256k of battery-backed RAM.
The bios copies the flash to fast RAM and maps it to the lower 512k, The
battery-backed RAM is mapped at the 512k address (0x80000). The upper
256k is mapped to flash so it can access the user and ID block.
So, all the RAM is available. xmem should be available from the end of
your code in fast RAM to the top of the bbram.
--
------
Scott G. Henion, Consultant
Web site: http://SHDesigns.org
------
(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )