LPC4330: USB on old Rev A chips not working

engineer_tom — Mon, 02 May 2022 12:50:23 GMT

Hello,

because of the chip shortage, we had to use some very old LPC4330/4350 devices. These appear to be still Rev A (and have the SPIFI reboot bug, etc.)

Sadly, USB0 is not working. We use the same code as for the newer Revisions, we checked the VBUS-Level (which is around 3.0V) and the USBCMD Bit0 (which is 1). Normally (and on newer Revs that is the case) the DP line should now go up to indicate a Full-Speed device to the host (which later should change to High-Speed). It does remain at 0V, though.

There is no difference in the errata that would indicate a different behavior in this case for Rev A or newer chips.

We then compared the USB registers and found a few differences. So we flipped Bit0 (VBUS_Discharge) on OTGSC and at least the DP line now went up and down and the Host started chirping (0.8V). Sadly the LPC did not answer that. After a short while the line goes down again and no USB communication does start. This behavior can be seen in the attached screenshot.

We also tested the LPC against several USB hosts (and hubs). None worked.

So why do the old Rev chips not work (when the newer ones on the otherwise same hardware do)?

Re: LPC4330: USB on old Rev A chips not working

engineer_tom — Fri, 06 May 2022 08:33:20 GMT

Well, we resolved it using the "usbdlib_for_LPC43xx" which replaces the chip-internal USB-ROM with a bug-fixed version during runtime. It increases our app size a bit, but at least it is working now.

https://www.nxp.com/docs/en/application-note/TN00041.zip

topic Re: LPC4330: USB on old Rev A chips not working in LPC Microcontrollers

LPC4330: USB on old Rev A chips not working

Re: LPC4330: USB on old Rev A chips not working