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).
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
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.