LMH1297: EOM Problems

Austin Keener

Part Number: LMH1297

Hello,

I am having troubles trying to read back the EOM data from the LMH1297 chip over SPI as outlined in the programming guide. The chip is set up in EQ mode with data entering on the SDI_IO pin. Upon reading the HEO and VEO registers, only 0s are returned. Also, when reading the EOM matrix, it seems like there are not any signal crossings, which would imply that the EOM is not locking onto the data rate. The interesting thing is that I am successfully passing data through the chip. I also noticed that both the carrier detect and course adaptation bits for SDI_IO was high, but I do not have a reclocker lock. I am assuming the reclocker not having a lock is what is causing the EOM to fail. Any suggestions on how to resolve this issue, or direction for diagnosing this issue would be appreciated.

Thanks!

Austin Keener

over 5 years ago

0 Nasser Mohammadi over 5 years ago

TI__Guru* 93670 points

Hi Austin,

EOM is operational if and only if device is locked. First need to get the device to lock to your data pattern. Aside from eye monitor, you can also check HEO/VEO to interrogate eye opening.

Regards,, Nasser

0 Austin Keener over 5 years ago in reply to Nasser Mohammadi

Prodigy 50 points

Nasser,

Just to clarify, the CDR has to achieve a data rate lock for the EOM be functional, right? Also, can the CDR lock onto non-SMPTE data rates? If not, is there a register to manually tune the CDR PLL?

Thanks,
Austin Keener

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LMH1297: EOM Problems