topic USB for lpc1768 and LPC1769 in LPC Microcontrollers

USB for lpc1768 and LPC1769

LPC-confuso — Thu, 15 Dec 2022 23:15:27 GMT

There is an LPCOpen example for the LPC1769 xpresso board that has a usbd_lib_cdc.bin example.

I though the USBD drivers were referring to internal ROM USB drivers. Does the lpc17xx have these? Am I mistaken about this? Does this example in fact work?
Is this interface the same for the LPC1768?
Is there anything special I need to do to compile the example for the LPC1768? I have changed the chip type in MCUxpresso IDE, but this did not work. The code runs but no USB connection occurs.
In the example, the symbols core_api, hw_api, and cdc_api get magically populated (by some ROM object file). Are these symbol addresses documented anywhere? Is the ROM the same on the LPC1768 and LPC1769?

Really I am just trying to get a functional virtual com port up and running on an LPC1768, but I am having a lot of trouble. Any suggestions for a working example would be great.

Thanks,

Steve

Re: USB for lpc1768 and LPC1769

Alice_Yang — Fri, 16 Dec 2022 08:31:00 GMT

Hello @LPC-confuso

Yes, LPC1769/lpc1768 have ROM USB driver. LPC1768 also can use it.

The difference between the two chips is the MAX cpu frequency :

Alice

Re: USB for lpc1768 and LPC1769

LPC-confuso — Fri, 16 Dec 2022 19:09:49 GMT

Hey @Alice_Yang, thank you for your prompt reply.

The information that everything is the same except for the clock speed is helpful. It points to the fact that my issue is HW based and not SW based.

It is interesting that these parts contain the ROM drivers. This feature is not mentioned heavily in the LPC17xx user manual compared with the LPC15xx user manual.

I did get the LPC1769 LPCXpresso usbd_lib_cdc example to work on the LPC1768 LPCXpresso board. For future readers I will mention what I had to do so you don't need to go through the same pain I did.

1. using lpcopen 2.10 for the LPCXPresso LPC1769 board

2. import the following examples into MCUXpresso IDE: usbd_llib_cdc, lpc_chip_175x_6x, lpc_board_nxp_lpcxpresso_1769

3. add the following line to board.c line 365: " \Chip_IOCON_PinMux(LPC_IOCON, 2, 9, IOCON_MODE_INACT, IOCON_FUNC1);"

I am not sure why this works. The LPCXpresso LPC1769 board also uses the USB_CONNECT pin... But the change enables the USB_CONNECT functionality which will initiate a connection.

The last thing i will mention: in my initial post point 4, the symbols are populated by linking with "libusbd_175x_6x_lib.a"

Re: USB for lpc1768 and LPC1769

LPC-confuso — Fri, 16 Dec 2022 19:36:47 GMT

Also my target is the lpc1768 mbed, not the xpresso board...