# BOB-12009 level shifter with Jetson Xavier AGX and linear servo - horrible signals

**URL:** <https://community.sparkfun.com/t/bob-12009-level-shifter-with-jetson-xavier-agx-and-linear-servo-horrible-signals/43159>\
**Category:** Miscellaneous\
**Created:** [December 9, 2021, 10:22pm UTC](https://community.sparkfun.com/t/bob-12009-level-shifter-with-jetson-xavier-agx-and-linear-servo-horrible-signals/43159 "2021-12-09T22:22:50Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Jlel12](https://avatars.discourse-cdn.com/v4/letter/j/d07c76/32.png) [@Jlel12](https://community.sparkfun.com/u/Jlel12)\
**Post date:** [December 9, 2021, 10:22pm UTC](https://community.sparkfun.com/t/bob-12009-level-shifter-with-jetson-xavier-agx-and-linear-servo-horrible-signals/43159/1 "2021-12-09T22:22:50Z")

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I’m trying to use the BOB-12009 level shifter to convert PWM signals from 3.3V (coming from a Jetson Xavier AGX) to 5V (driving an Actuonix 12V linear servo, which uses a 0-5V PWM signal as an input - example: [https://www.actuonix.com/L12-I-Micro-Li … /l12-i.htm](https://www.actuonix.com/L12-I-Micro-Linear-Actuator-Internal-Controller-p/l12-i.htm)). I am getting _garbage_ results. Here’s what happens:

- - When the Jetson's pins are not hooked up to the BOB-12009, everything looks fine - the 3.3V reference reads as 3.3V, the PWM signal is as expected.
- - When I plug the Jetson into the BOB-12009, the PWM signal still looks good, but the low value has been raised - now it's at 1.8V instead of 0V. At this point, I have 3.3V from the Jetson to LV, GND to GND, and PWM (Pin 18) to LV1. Nothing is hooked up to the HV side.
- - When I plug in the leads to the HV and GND ports on the other side of the BOB-12009 - even before I've turned the power supply on - the PWM waveform shifts again, now going between 750 mV and 2.6 V.
- - When I power up the 5V power supply, the signal shifts again, and the bottom half of the PWM waveform now gets really fuzzy. The high signal is back up to 3.3V, but the low signal is a fuzzy mess around 1.5V. (IIRC there is a display setting on my o-scope that may be impacting this/why it looks so "fuzzy", but I can't remember what it is/need to go look for it)
- - At this point, if I prove HV1 with my scope, it looks "appropriately bad" - high signal is at 5V, low signal is a gross mess also around 1.5V.
- What am I doing wrong here? I’m guessing that the Jetson’s outputs are not appropriate for this particular task (e.g. open collector when they’re not supposed to be or something) - am I on the right track here?

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**Author:** ![Jlel12](https://avatars.discourse-cdn.com/v4/letter/j/d07c76/32.png) [@Jlel12](https://community.sparkfun.com/u/Jlel12)\
**Post date:** [December 14, 2021, 4:13pm UTC](https://community.sparkfun.com/t/bob-12009-level-shifter-with-jetson-xavier-agx-and-linear-servo-horrible-signals/43159/2 "2021-12-14T16:13:21Z")

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Hey folks! Any thoughts here? Further background - here’s a description of what’s behind the pins on the Jetson (another level shifter!):

[https://developer.download.nvidia.com/a … 5jb21cLyJ9](https://developer.download.nvidia.com/assets/embedded/secure/jetson/Nano/docs/DA-09753-001_v1.0.pdf?gn3eT9BFlOP_ttephj-8FL6pVQklt3tUKZ-iO8ZXiggHmnSWIcq4usPkJeBBe4hn0vZ5UI9RjLS6_9gNXcJhXtaTJ8-oCshtjklDV_FM6uVujnU0e55SRZ7rsq3jEoEaKe6ujcRkwj2RgkacqS9aaV0D-iEj3vIFQu1Hxw&t=eyJscyI6ImdzZW8iLCJsc2QiOiJodHRwczpcL1wvd3d3Lmdvb2dsZS5jb21cLyJ9)

Thanks very much - appreciate your help!