topic Re: LPC546xx High sped USB compatibility in LPC Microcontrollers

LPC546xx High sped USB compatibility

revolutesea — Tue, 14 Jul 2020 03:01:28 GMT

I try to use LPC546xx High speed USB1 port to connect with Lenovo T420 by ISP mode. That have chance to fail ( unknow device ). Our LPC546xx's USB1 is pass eye diagram.

The following is LPC546xx USB1 eye diagram test.

However, Lenovo T420 always can detect hard disk thought High speed USB 2.0 mass storage. By the way I also serial USB cable to High speed USB 2.0 mass storage to simulate LPC546xx's situation.

I found LPC546xx USB1's high speed detect handshake have some abnormal waveform.

The following is LPC546xx high speed detect handshake waveform. ( Blue is D+, Yellow is D- )

This is fail waveform.

This is retry to success detect

The following is High speed USB 2.0 mass storage with USB cable. ( Green is D+. Purple is D- )

Re: LPC546xx High sped USB compatibility

FelipeGarcia — Wed, 15 Jul 2020 23:07:17 GMT

Hello,

First I would make sure that USB1 is working properly in your design. You could load a USB example first to verify.

Please see here: LPC546xx USB1 Examples

If the USBs get recognized somehow, but just as unknown device, then this could be a performance problem in your USB implementation. Either coming from a clock problem (inaccurate or with jitter or both) or from an electrical problem on USB D+ / D- (impedance mismatch, wrong protection diode circuit etc.)

I tried to reproduce this on my side using LPCXpresso54608 board but it was recognized correctly as a USB Mass Storage Device when entering USB 1 MSC ISP mode.

Best regards,

Felipe

Re: LPC546xx High sped USB compatibility

revolutesea — Thu, 16 Jul 2020 06:09:34 GMT

Hi Felipe

Our USB1 is a device that can work on hp envy, dell latitude, acer tmp, macbook pro, mac mini, lenovo t470, msi ps and at least 10 PCs. This USB1 device has passed the CV test.

The problem is that USB1 may fail to detected by USB2.0 port of Intel Core2 motherboard and Lenovo t420.

In summary, thank NXP for helping solve this problem through errata.

Thank you