Linux/DS80PCI102: DS80PCI102: Linux Driver

Hi Mahesh,

Are you using pin mode or SMBus mode to configure the DS80PCI102?

Do you know the approximate distances between the DS80PCI012 and the PCIe system components - AM5726 and Qualcomm modules? 

With this information I can suggest appropriate settings.

Regards,

Lee

We are using SMBus mode. The distance between AM5726 to DS80PCI012 is 13inch and DS80PCI012 to Qualcomm modules is 3 inch.

Regards,
Mahesh.

Hi Mahesh,

For the input connected to the AM5726:  Set EQ = 01'h

For the input connected to the Qualcomm device: Set EQ = 00'h

For the ouput connected to the AM5726: Set VOD = 1.0V and DEM = 0 dB

For the output connected to the Qualcomm device: Set VOD = 1.0V and DEM = 0 dB

Set the Rate pin = Float (Automatic Rate detection)

Set the RXDET pin = Float (Automatic Rx-Detect)

This should get the system going.

Regards,

Lee

Hi Lee,

Thanks for reply.

I have tried below setting as per your suggested but still not detecting the card. 

Channel A Qualcomm-Input & AM5726-Output 

EQ  0x0f = 0x00  

VOD 0x25 = 0xAC 

DEM 0x11 = 0x80

Channel B Qualcomm-Output  & AM5726-Input 

EQ 0x16 = 0x01 

VOD 0x2D = 0xAC

DEM 0x18 = 0x80 

Please refer below application schematic. Do we need to do anything configuration on HW side??

Regards,

Mahesh.

Mahesh,

I do not see anything in the schematic which would prevent the PCIe link from correctly detecting receivers in the upstream and downstream directions.

You could force our terminations to 50 Ohms to see if this can help the system configuration.

Write Registers

0x06 = 18'h

0x08 = 08'h

0x0E = 0C'h

0x15 = 0C'h

It is unusual for the PCIe system to fail in this way with our repeaters.

Are there AC coupling capacitors on the reciever pins?

Hi Lee,

Yes, there AC coupling capacitor on the receiver pin.

Regards,
Mahesh.

I have tried to configuration setting as per your suggested but still not detecting.

I able to detect the card when the bypass the repeater so without repeater working fine with repeater it has issue.

This is quite strange. Failure to detect in PCIe applications is rare.  Can you see RXDET pulses going into our receiver pins?

Thanks and Regards,

Lee

This our system block diagram and as per typical application in datasheet have two repeater.

Do we require the two repeater for our application??

Regards,

Mahesh.