Problems with high speed USB enumeration on LPC1823 custom hardware

[MarkDale]

When running our firmware on the LPC18S37 DVK the board enumerates over USB as high speed successfully.

Running the same firmware on our custom hardware the board enumerates as full speed.

We're using USB0.
On the scope, we don't see the chirp sequence prior to enumeration as if the board isn't attempting to enumerate as high speed.

We've removed all components on USB data lines between connector and MCU and see the same problem.

Have looked at the USB errata for LPC18xx and can't see anything that would cause this.

Have stepped through code prior to enumeration and setup in the USB registers looks correct to me.

[MarkDale · Accepted solution]

Thanks for your response. Sorry for the slow reply.
In the end, we had missed out the USB0_RREF resistor in our schematic design (see attached table from reference manual).

High speed USB comms now working as expected. 

[xiangjun_rong]

Hi,

If the firmware is the same, have you compared the schematics design?

BR

XiangJun Rong