Arduino Forum

Products => Arduino Due => Topic started by: prefect on Jul 30, 2013, 10:16 am

Title: Just for confirmation: DUE cannot have external parallel RAM?
Post by: prefect on Jul 30, 2013, 10:16 am
I am quite sad about this if true.

On the 2560 I loved the feature to add external RAM, but it had to be bankswitched.
On the DUE now, I do have speed and a good basis for RAM but I cannot extend (behold some SPI RAMs which are ... small ... by all means).

We got 24bit address range but no wire to plug the RAM in, right?
All that remains is to use  a software library to interface some static RAM??

:smiley-sad-blue: I could cry!  =(

Anybody having a clue on alternatives (do LARGE SPI RAMs exist maybe in the range of 512kB or anything else I can do with reasonable effort?)

Thanks in advance for any hints.

Best regards!
prefect
Title: Re: Just for confirmation: DUE cannot have external parallel RAM?
Post by: sierrasmith71 on Jul 30, 2013, 05:28 pm
There are large (128KB) i2C FRAM (non-volatile and fast) devices from several vendors. For example see: http://www.futureelectronics.com/en/technologies/semiconductors/memory/fram-mram/Pages/6338354-FM24V10-G.aspx (http://www.futureelectronics.com/en/technologies/semiconductors/memory/fram-mram/Pages/6338354-FM24V10-G.aspx)
Title: Re: Just for confirmation: DUE cannot have external parallel RAM?
Post by: sierrasmith71 on Jul 30, 2013, 05:40 pm
Better yet: a  40 MHz SPI 256K x 8 8 pin SOIC package F-RAM : http://www.digikey.com/product-detail/en/MB85RS2MTPF-G-JNERE2/865-1250-6-ND/4022691 (http://www.digikey.com/product-detail/en/MB85RS2MTPF-G-JNERE2/865-1250-6-ND/4022691)

David Garrison

Title: Re: Just for confirmation: DUE cannot have external parallel RAM?
Post by: LMI1 on Jul 31, 2013, 10:45 pm
I am not sure what kind of RAM you mean, but you can use ordinary parallel RAM (and ROM), if you have some IO pins left and multiplex them to drive what the memory needs. Was that what you meant by banking?
Title: Re: Just for confirmation: DUE cannot have external parallel RAM?
Post by: graynomad on Aug 01, 2013, 02:46 am
One of our members has added an external RAM, there's a thread about it somewhere.

There's a problem though with the connection of two pins (A6 and NRD or some such) and I can't remember how/if he got around that.

Personally I think that the Due design in this regard is a total screw up.

You could look at the Tiaijuino (sp?) board, they may have done a better job in this regard.

______
Rob
Title: Re: Just for confirmation: DUE cannot have external parallel RAM?
Post by: LMI1 on Aug 01, 2013, 04:57 am
Yes. I have seen that thread. "    
Parallel library for Due External Memory Bus/Static Memory Controller "

What is NRD?
Title: Re: Just for confirmation: DUE cannot have external parallel RAM?
Post by: ralphnev on Aug 01, 2013, 02:29 pm

Yes. I have seen that thread. "    
Parallel library for Due External Memory Bus/Static Memory Controller "

What is NRD?

NRD == RD active low
NWR == WR active low