NVME SSD PCIe communication


I develope custom board for our application and I am using Xavier NX emmc som in that.
In that carrier board I provide PCIe four lane M.2 socket for SSD connection.
I follow same schematic as given in Xavier NX devkit.
But unfortunately when I connect SSD in my board SOM is not booting up properly.
Please check attached excel file where I have given comparison of booting debug log of Devkit with and without SSD and Custom board booting debug log with and without SSD.
From observation it look like SOM is detecting the PCIe device but its not able to get its ID and other details.
Generally I have observe that along with PCIe lane there has to be I2C lane but in devkit there is no I2C communication between PCIe device and SOM.
Please guide me on this.
NVME Log.xlsx (88.0 KB)

Sorry to say this. But this is not a good idea to put your log in a excel file and show 4 of them at same time…

Please just upload 4 log files as attachment and just text file… We will check them by ourselves…


I am really sorry for that.
Please check attached log files.
03032023_CUST_SSD.log (41.1 KB)
03032023_CUST.log (41.3 KB)
03032023DEV_SSD.log (80.8 KB)
03032023DEV.log (37.9 KB)


Your log does not help because the kernel log is in silent mode… please remove quiet from extlinux.conf and dump log again…

BTW, if this is jetpack4.6.2, then please upgrade to jp4.6.3 because there is a known bug in cboot.


Thanks a lot for support.

I have disabled quite mode and took new set of logs.

Please find the attached log files of both Devkit and Our Custom board.
When we connect SSD to our Custom board , SOM is not able to boot up properly  and its stuck in some loop.

Please check the log and guide me on that.
Custom+SSD06032023.log (97.5 KB)
Custom06032023.log (99.0 KB)
Devkit+SSD06032023.log (81.2 KB)
DevKit06032023.log (86.0 KB)

Any updates on this.
I had one query that whether we require I2C communication along with PCIe lane?
Please guide me on this.

Any updates on this.


This is unknown. I’ve seen such error few years ago on another user’s custom board but no conclusion.

Please review your schematic with our design guide document if same device does not trigger this error on devkit.

Thanks a lot for reply.
Can you please confirm one thing that whether we require I2C interface along with PCIe lane while SOM interface with external SSD?
If you check Xavier NX devkit schematic there I2C2 is routed to M.2 socket through jumper but I dont know whether its connected or not.
Please guide me on this.

I am no hardware guy so cannot answer. I will ask them to check it but it needs to wait until Monday.

It would be nice if you could share your schematic.

Please find attached our custom boards schematic.
Here only one difference was there that M.2 ALERT pin previously I connected to GPIO 10 but as per devkit schematic I changed its connections to SDIO_D1 pin (221).
But still when I connect SSD to SOM board ,SOM start booting but its not finishing its booting.
I think its engaged in some loop.
SOM CONNECTION_2.pdf (510.9 KB)
NVME M2.pdf (316.8 KB)

I2C is optional, you need to check your SSD device spec for that.

Thanks a lot for reply.
So in Xavier NX devkit there is no I2C connection for M.2 SSD. right?

There is I2C connection (I2C2_MEM) to slot in devkit.


Thanks a lot for reply.

Yes there is signal shown in schematic.
But there is also link shown in schematic.

I was slightly confused that whether I2C2 is connected to SSD or not.
Because I2C2 already implemented for EEPROM communication.
In my custom board I have not include EEPROM.
I just want to know that is there any role of I2C in SSD communication?
Please give feed back on this.

I am using WD Blue SN570 (256GB) SSD.
It work fine with Xavier NX Devkit but same SOM and SSD I put it my board SOM is not booting properly.
Without SSD SOM boot properly.

As said, it depends on your SSD device. If I2C is needed, you can mount 0ohm resistor to R110 and R111.

Problem solved I can able to interface SSD with SOM.
Thanks a lot for support.

This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.