4 years, 7 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.

/media/uploads/hebryn/uart.png

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)

Håkon

Question relating to:

Hi,

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
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1 Answer

4 years, 7 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
D1P0_19P2_12
D0P0_18P2_11

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.


Assigned to Toyomasa Watarai 4 years, 7 months ago.

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