6 years, 11 months ago.

LPCXpresso11U68 UART overlapping

From what i can see the UART on arduino pins D1/D0(P0_18, P0_19) is used as the virtual serial port over USB? I am going to use a GPRS shield witch requires UART communication and uses D1/D0 and I would like to be debugging with printfs at the same time.


So my question is if there is a way to change the connections of the USB to serial? (I know this is possible on the Nucleo platforms)


Question relating to:


Just a quick question. Which revision of the board are you using? You can find a revision number in the back side of the board.

posted by Toyomasa Watarai 04 Mar 2015

Hi, I haven't actually ordered one yet, just wanted to know if this was possible at the newest revision.

posted by Håkon Bryn 04 Mar 2015

1 Answer

6 years, 10 months ago.

There are two revision of LPCXpresso11U68 board and D0/D1 pins are connected to different ports.

Arduino Shield receptacles nameRev.B boardRev.C board

Virtual serial port over USB (USBTX, USBRX) are connected to same port of interface chip.

Please refer following document about the difference between Rev.B and C. http://www.lpcware.com/system/files/LPCXpresso11u68-revC.pdf

Possible options are:

Rev.B board

I think it's not easy to use the Seeed GPRS shield with virtual serial over USB (for debug log etc) due to the overlapping issue.

To do this:

  • You have to cut the print circuit pattern between LPC11U68 and D0/1 pin (not between LPC11U68 and LPC4322)
  • Solder between D0/1 pin to other UART channel e.g. UART4

Here is an example of GPRSInterface initialization code.

Serial pc(USBTX, USBRX);
GPRSInterface gprs(P2_12, P2_11, 115200, "apn", "username", "password");

Rev.C board

No modification required for Rev.C board, but you must not specify D0/D1 pin name for Rev.C board since symbol names for LPC11U68 mbed SDK is defined for Rev.B board.

Serial pc(USBTX, USBRX);
GPRSInterface gprs(P2_12, P2_11, 115200, "apn", "username", "password");

Please note that I didn't have both Rev.C LPC11U68 and Seeed GPRS board, so I didn't test actual connection between these boards. Also, I am not sure the Rev.C board is available in the market yet.

Accepted Answer

Assigned to Toyomasa Watarai 6 years, 10 months ago.

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