# Servo signal with external interrupts

**URL:** <https://forums.openmv.io/t/servo-signal-with-external-interrupts/6986>\
**Category:** OpenMV Boards\
**Created:** [April 4, 2022, 12:18pm UTC](https://forums.openmv.io/t/servo-signal-with-external-interrupts/6986 "2022-04-04T12:18:42Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Andrew](https://avatars.discourse-cdn.com/v4/letter/a/f19dbf/32.png) [@Andrew](https://forums.openmv.io/u/Andrew)\
**Post date:** [April 4, 2022, 12:18pm UTC](https://forums.openmv.io/t/servo-signal-with-external-interrupts/6986/1 "2022-04-04T12:18:42Z")

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Why my code don’t work (No servo signal)?

 ![servo_control_ExtInt_code](https://canada1.discourse-cdn.com/flex029/uploads/openmv1/original/2X/d/db1425288e107fb160dc881ff2e956bfe5197df9.png)

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**Author:** ![iabdalkader](https://yyz1.discourse-cdn.com/flex029/user_avatar/forums.openmv.io/iabdalkader/32/1169_2.png) [@iabdalkader](https://forums.openmv.io/u/iabdalkader)\
**Post date:** [April 5, 2022, 1:34pm UTC](https://forums.openmv.io/t/servo-signal-with-external-interrupts/6986/2 "2022-04-05T13:34:05Z")

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First of all, don’t call `print()` in a callback, you shouldn’t call any function that allocates memory in a callback, try turning on an LED instead. Second, the while loop is probably changing the pulse\_width back to 1300 not sure what you’re trying to do.