DSC MC56F8357 External memory access problem

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DSC MC56F8357 External memory access problem

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tshah
Contributor II

Hello community people,

 

I'm working on integrating external data RAM as well as Program flash with the DSC MC56F8357. I use CW 8.0 version for the external memory development. I'm facing problem to map the external memory to the external RAM even though I mapped the address of the data memory correctly as per the memory mapping details. I use CPU properties to configure or initialise the external memory for data RAM as well as external program Flash. I connected the /DS to the data RAM and /PS to the Program flash.

 

Now I'm trying to make the external RAM as my data RAM but its not working even though its configured through CPU properties - > External memory Buses enabled

 

My Current project Settings are given below for your references. I have attached the memory interface also for your reference.

 

Program Memory - Internal

Data Memory - External

Initialise OMR - Yes. (Tried with yes and No )

 

Kindly help me to make the external memory up and running.  All your comments and guidelines/notes are most welcome.

 

Thanks.

 

Regards,

AT T

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8 Replies

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johnlwinters
NXP Employee
NXP Employee

Try using wait states for the RAM.

Also, try setting the DRV bit so that the interface is always driven.

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tshah
Contributor II

Thank you John for your inputs and the information.The Pseudo SRAM worked after I removed a memory mapped peripheral device that was multiplexed on the same bus.I used wait states for R/W operations and also set the drive bit.

Thanks again for the support.

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1,950 Views
Ben
Senior Contributor I

Hello AT

I developed a project with the same configuration: same chip, internal program memory, external RAM for large data memory. It works good after manually changing the configuration file and adding #pragma in code, however, I worked with CW10.6 and not with the old 8.0.

As far as I remember, I had problems using the 8.0 and I switched to 10.x

If you agree to  import the project to 10.6 I can send you details.

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tshah
Contributor II

Hello Ben,

Thank you very much for the information. Yes I agree, please send the detailsto import to 10.6

AT

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Ben
Senior Contributor I

In the project settings files open the linker command file (.cmd).

There are 2 changes you should add there:

1) define the external memory address range

cmd_linker_file_memory_definition.jpg

(see the .x_ex_data from address 0x10000)

At the end of the file add the section definition:

cmd_linker_file_section_definition.jpg

Now you can use this memory section.

In the code file add the following pragma:

external_RAM_pragma_in_code.jpg

That's all!

After making the changes in the cmd file, make sure too disable the automatic linker file creation, otherwise it will overrun your changes every time you'll rebuild the project

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tshah
Contributor II

Hello Ben,

I have configured the external bus for internal memory boot and support for internal as well as external data memory. I had multiplexed the bus between parallel NOR flash (CS0) from spansion and PSRAM (CS1) from ISSI. I can access the NOR flash but I couldn’t access the PSRAM.

I checked all the configurations and it’s correct. I doubt with my PSRAM is not supporting with the DSC. What SRAM do you suggest to use? I selected PSRAM for low cost reasons. It would be a great help if you can advise on this.

In my project I need only external data RAM (probably around 512KB). Please suggest which SRAM to go with


AT

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1,948 Views
Ben
Senior Contributor I

Hello AT

I used ISSI RAM (see attached) and it works good.

Ben

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tshah
Contributor II

Thankyou Ben.The Pseudo SRAM worked after I removed a memory mapped peripheral device on the same bus.Thank you for all the inputs and support.

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