Arm Mbed OS support forum

Lpc 1768 no usb serial to pc connection

Mbed OS Hello world!
#1

I have scoured the Mbed site and internet for a solution to this problem. I have followed all of the guidance for drivers and ports and still cannot get any output to a terminal window (Putty or CoolTerm).
I am using Windows 10 Home with the basic serial example program and get the following output to the terminal: $$$$10100f2ea3eced51bdc9897acd2f201d7596.

Your help would be greatly appreciated.

#include “mbed.h”

// define the Serial object
Serial pc(USBTX, USBRX);

DigitalOut led1(LED2);

int main() {
while (true) {
led1 = !led1;

    // Print something over the serial connection
    pc.printf("Blink! LED is now %d\r\n", led1.read());
    wait(0.5);
}

}

#2

Hello @girrion,

Please try this simple example to print something on the window and let us know.

Thanks & Regards,
Mayank
Team Mbed

#3

Hello @maygup01,

Thank you for the prompt reply.
Following your suggestion I have received the following (abbreviated) response from the compiler:
mbed compile -t GCC_ARM -m LPC1768
.
.
[Error] main.cpp@20,2: #error [NOT_SUPPORTED] test not supported

Following subsequent failures, I imported and tried mbed-os-example-blinky. This compiled and behaved as expected.

I then ran mbed detect and received the following output:

[mbed] Detected LPC1768, port None, mounted H:, interface version unknown:
[mbed] Supported toolchains for LPC1768

Target mbed OS 2 mbed OS 5 uARM IAR ARM GCC_ARM ARMC5
LPC1768 Supported Supported Supported Supported Supported Supported -

Supported targets: 1
Supported toolchains: 4

I note that despite Windows device Manager reporting the port etc (mbed Serial Port(COM3)) all working properly, the above report identifies no port.

If i use the MODE command, only COM1 is listed.

Your help is greatly appreciated.

Best regards,

Mark

#4

@girrion Did you reset your LPC1768 after flashing your original program?

As for “[Error] main.cpp@20,2: #error [NOT_SUPPORTED] test not supported”, you are missing macro definitions. Looks like the example defines one of them in mbed_app.json (not sure how the others are defined). See line 19 to 21. If you just want to see some actions, I think you can just comment these out.

#if !defined(MBED_CPU_STATS_ENABLED) || !defined(DEVICE_LPTICKER) ||      !defined(DEVICE_SLEEP)
#error [NOT_SUPPORTED] test not supported
#endif

In any case, you want to press the reset button after flashing a new program.

#5

Hello @lonesometraveler,

Thank you, commenting out the lines allowed the code to compile and flash to the LPC1768.

Best regards,

Mark

#6

Hello @maygup01,

Following @lonesometraveler advice, and compiling and flashing the code you suggested earlier to the LPC1768 resulted in LED1 blinking on and off a couple of times, but provided no printed output to any of the terminal programs.

COM3 is now listed by the MODE command

When I run mbedls the serial port is unknown.

Best regards,

Mark

#7

Hello @maygup01, @lonesometraveler,

I have resolved the port detection issue as you can see below

[mbed] Detected LPC1768, port COM3, mounted H:, interface version unknown:
[mbed] Supported toolchains for LPC1768

Target mbed OS 2 mbed OS 5 uARM IAR ARM GCC_ARM ARMC5
LPC1768 Supported Supported Supported Supported Supported Supported -

Supported targets: 1
Supported toolchains: 4

Using the mbed serial terminal
mbed sterm
and connecting to the LPC1768 board; I can reset from this terminal but I still cannot output anything to sterm, CoolTerm or Putty.

Hoping you can help with this.

I have re-run the test program you suggested in your first response and pasted the log output below.

Output from cpu-stats.log:

[1575134137.39][HTST][INF] host test executor ver. 0.0.10
[1575134137.39][HTST][INF] copy image onto target…
1 file(s) copied.
[1575134141.41][MBED][WRN] Target ID not found: Skipping flash check and retry
[1575134141.50][HTST][INF] starting host test process…
[1575134141.84][CONN][INF] starting connection process…
[1575134141.84][CONN][INF] notify event queue about extra 60 sec timeout for serial port pooling
[1575134141.84][CONN][INF] initializing serial port listener…
[1575134141.85][SERI][INF] serial(port=COM3, baudrate=9600, read_timeout=0.01, write_timeout=5)
[1575134141.85][SERI][INF] reset device using ‘default’ plugin…
[1575134141.86][HTST][INF] setting timeout to: 60 sec
[1575134142.11][SERI][INF] waiting 1.00 sec after reset
[1575134143.11][SERI][INF] wait for it…
[1575134143.11][SERI][TXD] mbedmbedmbedmbedmbedmbedmbedmbedmbedmbed
[1575134143.12][CONN][INF] sending up to 2 __sync packets (specified with --sync=2)
[1575134143.12][CONN][INF] sending preamble ‘fb5fe8bc-38dd-4b2b-b876-079f99dea266’
[1575134143.12][SERI][TXD] {{__sync;fb5fe8bc-38dd-4b2b-b876-079f99dea266}}
[1575134148.12][CONN][INF] Reset the part and send in new preamble…
[1575134148.12][SERI][INF] reset device using ‘default’ plugin…
[1575134148.39][SERI][INF] waiting 1.00 sec after reset
[1575134149.39][SERI][INF] wait for it…
[1575134149.39][CONN][INF] resending new preamble ‘ca76689e-0531-4b9e-8882-2c3b465ecb3c’ after 5.00 sec
[1575134149.39][SERI][TXD] {{__sync;ca76689e-0531-4b9e-8882-2c3b465ecb3c}}
[1575134149.42][HTST][ERR] None
[1575134149.42][HTST][WRN] stopped to consume events due to __notify_sync_failed event
[1575134149.43][HTST][INF] __exit_event_queue received
[1575134149.43][HTST][INF] test suite run finished after 7.57 sec…
[1575134149.43][HTST][INF] CONN exited with code: 0
[1575134149.43][HTST][INF] No events in queue
[1575134149.43][HTST][INF] host test result() call skipped, received: sync_failed
[1575134149.43][HTST][WRN] missing __exit event from DUT
[1575134149.43][HTST][INF] calling blocking teardown()
[1575134149.44][HTST][INF] teardown() finished
[1575134149.44][HTST][INF] {{result;sync_failed}}

#8

Hello girrion,

Does your LPC1768 board use the latest firmware?

#9

Hello @hudakz,
The board has the latest firmware (141212) and flashes programs with no difficulty, both from the online and off line compilers. Additional programs such as “Use the U and D keys to make LED1 brighter or dimmer” from the “Board to PC communication over USB” manual function as expected, but no text data can be sent to a terminal e.g. Putty, CoolTerm or sterm. Interestingly each time I disconnect from a terminal and reconnect, the terminal displays the following $$$$10100f2ea3eced51bdc9897acd2f201d7596, which seems to be “target_id_usb_id”: “10100f2ea3eced51bdc9897acd2f201d7596”.

I need to resolve this issue quickly, so any help you can offer will be greatly appreciated.

Best regards

#10

Some people complainded that serial port worked only when the LPC1768 was plugged into a USB port on the back of the PC’s motherboard.

#11

Have tried various USB ports with no luck. I have also tried re-numbering the COM port, again with no positive result.

#12

Hi @maygup01,
Have you had an opportunity to review the information I have posted?
I have had no luck resolving this issue of serial to pc comms (print output to screen) and would really appreciate your input.

Best regards

#13

I’m having much the same problem as Mark, only mine is using a new Win10 machine, Any resolution on this problem? My code use to work in 2018 when I first wrote it and was using TeraTerm. I could run the code and see the data. Now, TeraTerm doesn’t seem to work nor Putty. My code has all the same required lines for using a serial port.

#14

…but after 2 hours with another mbed programmer, we discovered:

//in order to have a serial terminal viewer working to view your code’s output…
//go to https://os.mbed.com/handbook/Windows-serial-configuration
//to download the mBED WINDOWS SERIAL PORT DRIVER

putting this into all my comment sections.

#15

//in order to have a serial terminal viewer working to view your code’s output…

//go to https://os.mbed.com/handbook/Windows-serial-configuration

//to download the mBED WINDOWS SERIAL PORT DRIVER

#16

Hi

please see this in our docs:
https://os.mbed.com/docs/mbed-os/v6.1/program-setup/serial-communication.html

Certainly implies for Windows 7 a separate serial driver may be required, This may also be the case for Windows 10 (it wouldn’t hurt to try it).

Regards
Anna