LPC3250 EMC interface with Spartan-6 FPGA

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LPC3250 EMC interface with Spartan-6 FPGA

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Contributor I

Hi,

I'm using LPC3250 to communicate with my FPGA through EMC interface.

When doing a read operation my data is read as a constant value (in my case specifically 0x0008).

I brought out the EMC pins on board and used a scope to tap the signals, I see that the EMC signals (Figure (1)) are meeting the specified timing requirements as mentioned in the datasheet. But the data latched by the controller is 8 instead of 205.

                                                                                 Figure (1).

pastedImage_3.png

Following are the EMC configuration details for the above observation.

WAITOEN = 0x2

WAITRD = 0xA

Bus Width = 16 bits

CS Polarilty = Active low

HCLK = 104MHz

I have tried with increasing and decreasing the wait states but nothing seems to work.

Am I missing something here?

Please help.

Thanks,

Vijay

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NXP Employee
NXP Employee

Don't know what happens before you read the value 205, but don't forget that the EMC has read buffers and that there is sometimes a burst read. So if you request a byte read from address x, the EMC will read more bytes than really necessary. If in the next step you want to read from address x+2, the value is taken from the buffer and not from the outside memory.

I didn't check whether the real cache of the ARM9 could also have an impact, maybe you should check this in a second step.

Regards,

Bernhard.

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