# ChromeOS Serial Monitor - Doesn't Work with Uno R4 Wifi

**URL:** <https://forum.arduino.cc/t/chromeos-serial-monitor-doesnt-work-with-uno-r4-wifi/1288147>\
**Category:** Cloud Editor\
**Created:** [August 3, 2024, 7:27pm UTC](https://forum.arduino.cc/t/chromeos-serial-monitor-doesnt-work-with-uno-r4-wifi/1288147 "2024-08-03T19:27:26Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![robotsrobots123](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/robotsrobots123/32/973914_2.png) [@robotsrobots123](https://forum.arduino.cc/u/robotsrobots123)\
**Post date:** [August 3, 2024, 7:27pm UTC](https://forum.arduino.cc/t/chromeos-serial-monitor-doesnt-work-with-uno-r4-wifi/1288147/1 "2024-08-03T19:27:26Z")

</div>

Hello,

The serial monitor doesn't work on my Chromebook when using the Web Editor.

Hardware: Uno Rev 4 Wifi  
ChromeOS: 126.0.6478.222 (Official Build) (64-bit)  
Uno Rev 4 Wifi FW 0.4.1

Current Setup:

1. I can detect the device and upload code to the device.
2. The device is running the code - see sample below. The builtin LED is on and the Tx LED transmits once a second.
3. This works just find on another Windows Laptop.
4. When I click on the serial monitor, "Connecting..." shows up, and then goes away.

In the upper corner of the serial monitor, I see:  
Arduino UNO R4 WiFi  
Port: 0x2341/0x1002

**CODE**

```arduino
void setup() {
  Serial.begin(9600);
  while (!Serial);
  Serial.println("Setup");
  pinMode(LED_BUILTIN, OUTPUT);
  digitalWrite(LED_BUILTIN, HIGH); // Turn on LED, so I know setup() completed
}

void loop() {
  Serial.println("Hello");
  delay(1000);
}

```

I'm a controls engineer by trade and happy to responsively dig deep into suggestions.

I tried changing the baud rate, rebooting the device, reloading the webpage, etc. Hope someone can help!

---

<div class="post-metadata">

**Author:** ![robotsrobots123](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/robotsrobots123/32/973914_2.png) [@robotsrobots123](https://forum.arduino.cc/u/robotsrobots123)\
**Post date:** [August 3, 2024, 10:33pm UTC](https://forum.arduino.cc/t/chromeos-serial-monitor-doesnt-work-with-uno-r4-wifi/1288147/2 "2024-08-03T22:33:38Z")

</div>

This is an interesting one, I have a second Chromebook and this one also connects, downloads, and the serial monitor does work just fine.

They're both requesting and getting permission to serial device "UNO WiFi R4 CMSIS-DAP (ttyACM0)"

Still eager to troubleshoot this - I’m able to debug Chrome via logging and events if needed.

---

<div class="post-metadata">

**Author:** ![system](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/system/32/1140315_2.png) [@system](https://forum.arduino.cc/u/system)\
**Post date:** [January 30, 2025, 10:33pm UTC](https://forum.arduino.cc/t/chromeos-serial-monitor-doesnt-work-with-uno-r4-wifi/1288147/3 "2025-01-30T22:33:57Z")

</div>

This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.