topic Re: LPC5528 Force USB1 as Full speed Device in LPC Microcontrollers

LPC5528 Force USB1 as Full speed Device

tks11111 — Tue, 28 Nov 2023 01:51:30 GMT

Hi,

I'm using the LPC5528 to run a project, and I need to support both high speed USB and full speed USB by using USB1. I saw there is a Forced FS bit in USB1->DEVCMDSTAT that might be able to deal with it.

However, as I know, there are some differences between high speed USB and full speed USB such as the clock and the descriptor.

My questions are:

1. Do we need to do any configuration after setting the Forced FS bit to 1 if I want to force USB1 as a USB full speed device.

2. Do we need to adjust any clock setting for it?

3. Is there any sample code that can be referenced? (toggle USB high speed and USB full speed in USB1)

Re: LPC5528 Force USB1 as Full speed Device

Alice_Yang — Thu, 30 Nov 2023 09:25:54 GMT

Hello @tks11111

Setting the Force FS bit to 1 is the only thing that is required.

Nothing else needs to be done. Clocks and other items are automatically configured by the HW in the correct mode.

Alice

Re: LPC5528 Force USB1 as Full speed Device

tks11111 — Thu, 30 Nov 2023 09:51:13 GMT

Hi Alice,

Thanks for the quick reply.

I had a quick question. If I want to toggle the USB1 between High Speed and Full Speed, I need to

call NVIC_SystemReset() and then toggle the Forced FS bit in the beginning, right?