Keysight LPDDR5, User Manual

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LPDDR5 Decoder User’s Guide 7
Setting Up for LPDDR Bus Decode 2
Sampling Positions
Sampling positions tell the logic analyzer when each signal is valid. Correct sampling positions are
required for Command and Address, Read Data, and Write Data to reliably capture data on your bus.
If you need assistance in setting sampling positions correctly, please contact your Keysight
Technologies representative.
Field Description
Chip Selects You must enable all chip selects that are being used in the system to ensure that the decoder functions correctly.
Likewise, any chip selects that are not used must not be enabled.
Bank Mode Choose the type of LPDDR5 bank mode reflecting your bank architecture.
The decoder supports the following three bank modes.
• BG - Bank-group mode (4 Banks, 4 Bank-groups)
• 8B - 8-Bank
• 16 B - 16-Bank
Refresh Management Select this checkbox if your LPDDR5 bus is using the Refresh Management (RFM) feature and therefore you want
to instruct the decoder to account for the occurrence of Refresh Management commands.
Match Read/Write to Activate Select this checkbox if you want the decoder to match the Read and Write commands to the corresponding
Activate commands in the captured data.
Max Search Depth This field is enabled only when you select the Match Read/Write to Activate checkbox.
This field allows you to specify the limit for the number of row addresses that the Decoder should search to find a
matching Activate corresponding to a Read or a Write command in the captured data.
The default value is 1024.
This limit is specially useful when:
• you have qualified the storage to NOT store the Activates.
• the Activate may not be available for some read/write commands. For instance, during the initialization phase
of the LPDDR5 bus.
By specifying a shorter search limit, you can significantly reduce the processing time taken by the decoder in
searching extensively for the matching Activates in situations such as those mentioned above. However, if you
notice that the search limit is so short that the Activates present in the trace are not being found by Decoder and
the decode for Read/Write is showing "Row Address = Unknown", then you can increase this limit.
NOTE
The DDR Setup Assistant tool automatically sets the required sampling
positions on your DDR command, address, and data read and write signals.