What is the function of the DQS line with SDRAM?

cancel
Showing results for 
Search instead for 
Did you mean: 

What is the function of the DQS line with SDRAM?

115 Views
Contributor I

What is the purpose and function of the DQS signal in the SEMC SDRAM interface?

Labels (1)
0 Kudos
5 Replies

98 Views
NXP TechSupport
NXP TechSupport

Hi Gerry,

DQS signal is to compensate the delay of data path and clock.  Certain devices use this pin to indicate the dummy cycles needed (before Program/Read data transfer).

Best regards,

Felipe

-------------------------------------------------------------------------------

Note:

- If this post answers your question, please click the "Mark Correct" button. Thank you!

- We are following threads for 7 weeks after the last post, later replies are ignored. Please open a new thread and refer to the closed one, if you have a related question at a later point in time.

------------------------------------------------------------------------------ 

0 Kudos

94 Views
Contributor I

Hi Felipe,

Thanks for the response however you don't explain how this is signal is used in the RT1050 with SDRAM. Is it an input to the 1050? If so, how is it used internally and how is it normally connected to external circuitry?

Regards,

Gerry

0 Kudos

79 Views
NXP TechSupport
NXP TechSupport

Hi Gerry,

SEMC_DQS is input/output when the MCU writes data to the SDRAM, it outputs the DQS in the center of the data it is writing. When reading data, the SDRAM sends the DQS edge aligned with the data.

 

image.png

The recommendation is to leave the pin floating and internal loopback enabled as this is needed for SDRAM read and write operations at 166 MHz, otherwise performance will not be optimal.

image.png

Best regards,

Felipe

-------------------------------------------------------------------------------

Note:

- If this post answers your question, please click the "Mark Correct" button. Thank you!

- We are following threads for 7 weeks after the last post, later replies are ignored. Please open a new thread and refer to the closed one, if you have a related question at a later point in time.

------------------------------------------------------------------------------ 

 

 

0 Kudos

73 Views
Contributor I

Hi Felipe,

Thanks for the information and the recommendation not to use the DQS line. However, I would like to understand it's function in detail. Is there documentation about this functionality with timing diagrams?

Regards,

Gerry

0 Kudos

49 Views
NXP TechSupport
NXP TechSupport

Hi Gerry,

You can find timing diagrams in our Reference Manual.

Regards,

Felipe

0 Kudos