# Switch off devices attached to board to save energy

**URL:** <https://www.thethingsnetwork.org/forum/t/switch-off-devices-attached-to-board-to-save-energy/30450>\
**Category:** End Devices (Nodes)\
**Created:** [October 3, 2019, 9:25am UTC](https://www.thethingsnetwork.org/forum/t/switch-off-devices-attached-to-board-to-save-energy/30450 "2019-10-03T09:25:24Z")\
**Posts on this page:** 1\
**Showing post:** 44

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**Author:** ![bluejedi](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/bluejedi/32/44639_2.png) [@bluejedi](https://www.thethingsnetwork.org/forum/u/bluejedi)\
**Post date:** [October 16, 2019, 1:03pm UTC](https://www.thethingsnetwork.org/forum/t/switch-off-devices-attached-to-board-to-save-energy/30450/44 "2019-10-16T13:03:54Z")

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> [@cslorabox](#):
>
> > invalid state sda(21)=0, scl(22)=0
> 
> That makes it sound like your pins are stuck low. Might be the ESP, might be something else holding them down.

@Verkehrsrot Are the ESP32 I2C issues described in this topic caused by what is described here:?: [TTGO T-Beam V1.0 & OLED & deep sleep needs proper power design](https://www.thethingsnetwork.org/forum/t/ttgo-t-beam-v1-0-oled-deep-sleep-needs-proper-power-design/30800)

In that case the I2C issues are not ESP32 related at all, but caused by an ill-behaving external OLED display.

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