Question about SATA eye pattern test

Hi,

The way we take the Eye Diagram is after placing the h/w into testmode.

There are couple ways to do that.

One way is to use the BIST Activate FIS where a remote device places our h/w into testmode by sending BIST Activate FIS. The h/w transitions to BIST-L mode when BIST Activate FIS is received automatically. You start with a normal link establishment process. Soon as Link is established, you will need to set P0CMD[ST=bit0]. The h/w will then goes into test mode when a BIST Activate FIS is received and will loop back the data sent by the remote device. See SATA spec for BIST Activate FIS and BISTAFR register description of the user's guide. The is BIST-L mode.

The other way to do it is to force the h/w to go into testmode and push one of the supported data pattern out.

For that you will need to initialize the h/w as you normally do but since you do not have a remote device available, you will not be establishing a link. You will configure BISTCR[PATTERN] with the pattern type you want to drive out and you will set BISTCR[TXO] bit. This is BIST-T mode.

Caution

When taking an Eye Diagram you would want the signals directly from the data lines (not tapping on the connector). For this reason, you will need to purchase a breakout board that would break out the data lines from iSATA connector to SMA. That way using matched SMA cables, you can connect the data lines directly to a scope. However, if you attempt to capture the Eye by tapping onto the back of a connector, you will introduce SI issue and you will not be getting a valid Eye diagram.

Best regards, Zegeye