Ошибка при открытии последовательного порта dev ttyacm0

I just had this problem with my Genuine Arduino Mega 2560 trying to connect to it from an Ubuntu 18.04.5 LTS machine using a locally compiled Arduino IDE version 1.8.16. I was able to fix it in my case, so posting here to share the tips.

Came across several other forum topics reporting the same symptoms (even though not all are Mega and not all on Linux):

• https://arduino.stackexchange.com/questions/33505/why-do-i-get-avrdude-stk500v2-receivemessage-timeout-error-when-uploading-to?newreg=d5f1171d37394be584fc5de8dea6138f
• https://arduino.stackexchange.com/questions/3316/mega-2560-doesnt-respond
• https://forum.arduino.cc/t/mega2560-timeout-communicating-with-programmer/132479
• https://starter-kit.nettigo.eu/2015/serial-port-busy-for-avrdude-on-ubuntu-with-arduino-leonardo-eth/

After troubleshooting for several hours I was able to reliably connect to my Mega. It turned out there were multiple problems that prevented it from working that had to be understood and solved, and when I realized what they were I could not believe my eyes.

The posters who suggested making sure that udev rules are configured to prevent the ModemManager from hogging the Mega device, thereby making it unavailable to the Arduino IDE were on the right track. So I checked my /etc/udev/rules.d/70-snap.core.rules and indeed confirmed that there already was a rule for ModemManager to ignore devices with USB vendor ID 2341, which is the Genuine Arduino:

...
ATTRS{idVendor}=="2341", ENV{ID_MM_DEVICE_IGNORE}="1"
...

However, when I did a tail -f /var/log/syslog and plugged in the Mega, I could not believe my eyes to see that ModemManager was still trying to talk to it:

Dec  9 22:09:58 hostname ModemManager[999]: <info>  [device /sys/devices/pci0000:00/0000:00:14.0/usb3/3-2] creating modem with plugin 'Generic' and '1' ports
Dec  9 22:09:58 hostname ModemManager[999]: <warn>  Could not grab port (tty/ttyACM0): 'Cannot add port 'tty/ttyACM0', unhandled serial type'
Dec  9 22:09:58 hostname ModemManager[999]: <warn>  Couldn't create modem for device '/sys/devices/pci0000:00/0000:00:14.0/usb3/3-2': Failed to find primary AT port

It looks like the ModemManager was still trying to connect to it as a non-USB TTY device.

The problem was exacerbated in that the Arduino IDE was not handling this problem gracefully and kept hanging and trying to connect to the Mega even after I unplugged it from the USB. Nevertheless, I did a quick ps -ef | grep ModemManager and then kill [PID], waited until the Arduino IDE stopped trying to connect to the disconnected Mega, then plugged it back in, specified the port via ‘Tools’ -> ‘Port’, and again attempted an upload, and it worked like a charm. (Conversely, had I just waited watching /var/log/syslog for ModemManager to give up and free the device Arduino IDE might have also worked without me explicitly killing the ModemManager. That probably explains why it worked sporadically.)

So then I thought I solved all my problems and started bolting the Mega into my device. I tightened the connecting fasteners, and again could not believe my eyes that it stopped working again. Took the Mega back out, unbolted the whole board and now it worked, bolted it back in, and it stopped working. After several rounds, correlated the use of a brass standoff on the hole right next to the pin A6 as causing this problem. I surmise that the metal standoff was shorting out or somehow interfering with PCB traces that run very close to that hole. So stopped bolting in that hole, and the Mega started working fine assembled into my device.

So in my case, 2 problems were preventing the Mega from working and PC connecting to it via USB:

(1) ModemManager was hogging the device as soon as it was plugged in despite the udev USB rules. Solution — killed ModemManager (still need to look into modifying system config so that I don’t have to kill it each time).

(2) Hardware issue with the metal riser interfering with PCB traces near hole next to pin A6. Solution — stopped bolting in that hole.

Hope this is helpful.

I am trying to work with the (new) sparkfun razor IMU 9dof, I wrote a silple sktetch to calibrate the magnetometer:

#include <SparkFunMPU9250-DMP.h> // Include SparkFun MPU-9250-DMP library
#include <Wire.h> // Depending on your Arduino version, you may need to include Wire.h
MPU9250_DMP imu; // Create an instance of the MPU9250_DMP clas
void setup() {
  Serial.begin(115200);

  Serial.println(F("Adafruit 10 DOF Board AHRS Calibration Example")); Serial.println("");

  if (imu.begin() != INV_SUCCESS){
    while (1) {
    Serial.println("Failed to initialize MPU-9250, loop forever");
   }

  }

 imu.setGyroFSR(2000); // Set gyro to 2000 dps

 imu.setAccelFSR(2); // Set accel to +/-2g

 imu.setLPF(5); // Set LPF corner frequency to 5Hz

 imu.setSampleRate(100); // Set sample rate to 10Hz

imu.setCompassSampleRate(100); // Set mag rate to 10Hz
}

void loop(void){
  imu.update();

  // Print the sensor data
  Serial.print("Raw:");
  Serial.print(imu.ax);
  Serial.print(',');
  Serial.print(imu.ay);
  Serial.print(',');
  Serial.print(imu.az);
  Serial.print(',');
  Serial.print(imu.gx);
  Serial.print(',');
  Serial.print(imu.gy);
  Serial.print(',');
  Serial.print(imu.gz);
  Serial.print(',');
  Serial.print(imu.mx);
  Serial.print(',');
  Serial.print(imu.my);
  Serial.print(',');
  Serial.print(imu.mz);
  Serial.println();  

  delay(50);
}

To be sure the Arduino IDE can access to dev/ttcACM0, I did sudo chmod 666 /dev/ttyACM0

I can dowload successfully but when I want to open the terminal I got the following error:

Erreur d’ouverture du port série « /dev/ttyACM0 ». (Port busy) (see attached screenshot)

More over when I entered dmesg on the console, I can see the following messages:

[   94.133923] usb 3-2: USB disconnect, device number 2
[   94.133978] cdc_acm 3-2:1.1: urb 12 failed submission with -19
[   94.135862] cdc_acm 3-2:1.1: urb 13 failed submission with -19
[   94.136059] cdc_acm 3-2:1.1: urb 14 failed submission with -19
[   94.136257] cdc_acm 3-2:1.1: urb 15 failed submission with -19
[   94.136457] cdc_acm 3-2:1.1: urb 2 failed submission with -19
[   94.136656] cdc_acm 3-2:1.1: urb 3 failed submission with -19
[   94.136852] cdc_acm 3-2:1.1: urb 5 failed submission with -19
[   94.137048] cdc_acm 3-2:1.1: urb 6 failed submission with -19
[   94.138841] xhci_hcd 0000:03:00.0: WARN Cannot submit Set TR Deq Ptr
[   94.138843] xhci_hcd 0000:03:00.0: A Set TR Deq Ptr command is pending.
[   94.931853] usb 3-2: new full-speed USB device number 3 using xhci_hcd
[   95.316578] usb 3-2: New USB device found, idVendor=1b4f, idProduct=9d0f
[   95.316581] usb 3-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[   95.316582] usb 3-2: Product: SFE 9DOF-D21
[   95.316584] usb 3-2: Manufacturer: SparkFun
[   95.320306] cdc_acm 3-2:1.0: ttyACM0: USB ACM device
[  858.774849] usb 3-2: USB disconnect, device number 3
[  904.529058] TCP: wlp1s0: Driver has suspect GRO implementation, TCP performance may be compromised.

Does anyone outhere experienced such issue?

Thank you for your help

Fabrice