# ESC Calibration Failed: "Can't open PWM device"

**URL:** <https://forum.theavr.org/t/esc-calibration-failed-cant-open-pwm-device/299>\
**Category:** Technical Support (Official)\
**Created:** [October 27, 2022, 2:19pm UTC](https://forum.theavr.org/t/esc-calibration-failed-cant-open-pwm-device/299 "2022-10-27T14:19:52Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![CK1010](https://avatars.discourse-cdn.com/v4/letter/c/5e9695/32.png) [@CK1010](https://forum.theavr.org/u/CK1010)\
**Post date:** [October 27, 2022, 2:19pm UTC](https://forum.theavr.org/t/esc-calibration-failed-cant-open-pwm-device/299/1 "2022-10-27T14:19:52Z")

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Our motors haven’t been spinning when being tested and whenever the ‘ESC PWM Minimum and Maximum Calibration’ is run we get an error saying “calibration failed, can’t open PWM device.” Additionally, whenever the drone is plugged in we only get the first 3 of the 5 beeps, how can we fix this so we can do our first flight test?

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**Author:** ![bhanner-bell](https://yyz1.discourse-cdn.com/flex007/user_avatar/forum.theavr.org/bhanner-bell/32/20_2.png) [@bhanner-bell](https://forum.theavr.org/u/bhanner-bell)\
**Post date:** [October 27, 2022, 6:52pm UTC](https://forum.theavr.org/t/esc-calibration-failed-cant-open-pwm-device/299/2 "2022-10-27T18:52:37Z")

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You are seeing this error on QGroundControl? Double check that your flight controller has been flashed and then double check that the PWM breakout board is correctly connected to the flight controller itself.

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**Author:** ![CK1010](https://avatars.discourse-cdn.com/v4/letter/c/5e9695/32.png) [@CK1010](https://forum.theavr.org/u/CK1010)\
**Post date:** [October 27, 2022, 7:47pm UTC](https://forum.theavr.org/t/esc-calibration-failed-cant-open-pwm-device/299/3 "2022-10-27T19:47:36Z")

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The error is dictated QGroundControl when running ESC calibration. We have flashed the firmware from the file provided at the GitHub repo several times and tried replacing both the PWM breakout board and the wire that it connects to the FC but the error still comes up. Everything else on the drone works, it just seems to be the motors.

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**Author:** ![CK1010](https://avatars.discourse-cdn.com/v4/letter/c/5e9695/32.png) [@CK1010](https://forum.theavr.org/u/CK1010)\
**Post date:** [October 28, 2022, 2:03pm UTC](https://forum.theavr.org/t/esc-calibration-failed-cant-open-pwm-device/299/4 "2022-10-28T14:03:54Z")

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The only abnormality we can find is on the left “I/O” side of the FC, the “B/E” light is orange whereas in the tutorial the light is meant to be off.

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**Author:** ![CK1010](https://avatars.discourse-cdn.com/v4/letter/c/5e9695/32.png) [@CK1010](https://forum.theavr.org/u/CK1010)\
**Post date:** [November 3, 2022, 2:33pm UTC](https://forum.theavr.org/t/esc-calibration-failed-cant-open-pwm-device/299/5 "2022-11-03T14:33:03Z")

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Our FC was broken, we got a new one and it works