SDRAM Controller

Can you explain to me about DQM (data mask) signal? How can i write RTL code for this signal?

Can you explain to me about DQM (data mask) signal? How can i write RTL code for this signal?

Can you explain to me about DQM (data mask) signal? How can i write RTL code for this signal?

dqm is used as (usually bytewise) enable signal. You only need it if a partial write is intended, e. g. whem you have a 16 bit wide memory but want to write single bytes without affecting the other half word. It's present in the previously posted refernece designs and documents but must not necessarily be used.

can i assign dqm signal equal 1 (hight level)?

Yes, you can assign constant '1' to dqm respectively hardwire the pins to VDD if you don't need to perform partial writes.

But dqm is a internal signal.What will happend if i assign constant 1 to dqm?I read in specification, they said that: I a given dqm signal is registered LOW, the corresponding data will be written to the memory; if the dqm signal is registered HIGH, the coresponding data inputs will be ignored, and a write will not be executed to that byte/column location".

Yes, you are correct, DQM is active low, so you have to pinstrap it to GND if unused.

Can you give me the code for this dqm?

DQM = 0 if no selective write is intended. Otherwise, DQM should be handled by the SDRAM controller.