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gauteh / omb-2024-nano

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Iridium: power-down #14

Open gauteh opened 3 months ago

gauteh commented 3 months ago

I have On/Off connected to A14 on Artemis Nano (AD35). It seems to turn the modem off and on, and holds the voltage low. But when the whole board powers down it seems to return to floating voltage.. thus powering the modem back on.

jerabaul29 commented 3 months ago

Could an easy quick fix solution be to put an external pull down resistor? If putting 100kOhm or more for example the power consumption associated would be negligible (would need to check if it is ok to have such a high R value, or if something a bit lower is needed to pull strong enough).

I could not see anything obvious in the sleep preparation function

https://github.com/jerabaul29/OpenMetBuoy-v2021a/blob/129916e1e05f97facc37a9b5c94781a2f2e4fec0/legacy_firmware/firmware/plain_gps_drifter/sleep_manager.cpp#L67-L106

that would affect AD35. May be some weird effect of putting the MCU into sleep / switching some parts of it off?

gauteh commented 3 months ago

Yes, that is a good idea.

tir. 13. aug. 2024, 12:50 skrev JR @.***>:

Could an easy quick fix solution be to put an external pull down resistor? If putting 100kOhm or more for example the power consumption associated would be negligible (would need to check if it is ok to have such a high R value, or if something a bit lower is needed to pull strong enough).

I could not see anything obvious in the sleep preparation function

https://github.com/jerabaul29/OpenMetBuoy-v2021a/blob/129916e1e05f97facc37a9b5c94781a2f2e4fec0/legacy_firmware/firmware/plain_gps_drifter/sleep_manager.cpp#L67-L106

that would affect AD35. May be some weird effect of putting the MCU into sleep / switching some parts of it off?

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jerabaul29 commented 3 months ago

:) .

(I have seen quite many "weird" (I put in "" because it may be written somewhere deep into the datasheet, then it is not weird, just that I am ignorant :) ) effects with pins high / low / floating etc depending on sleep conditions both on arduinos with ATMEGA, SAM, etc, so I do not take a chance on this any longer - I just always put the relevant pull ups or pull downs to make sure that the state of all important pins, like enable ones, is well defined as soon as there is power, even if the MCU does something weird :) )