Nodemanage + EasyPCB Sleep

[MatiasV]

@ElCheekytico, I was asking myself the same question about @user2684 approach.

For my power hungry sensors I'm experimenting using an 2n2222A Transistor with mixed success. (following this and that instructions ).

All works OK with sensors as DHT22 and similar digital devices, but I can't make it work with Analog sensors as an soil moisture sensor. I need to test, but I believe is because the voltage drop disturbing the AREF.

[Phil Whitmarsh]

@MatiasV to switch on/off power to sensors and oled displays it is best to use a logic level P-channel Fet, something like an Si2305, it is not good practice to switch power to sensors/displays by switching the ground, it's OK for a relay though.

See this link
https://www.avrfreaks.net/forum/hi-side-fet-switch-low-voltage

[user2684]

@ElCheekytico my bad sorry I was referring to a PNP2222a or similar and for some reason I wrote down MCP1702. Yes, this is the approach I'm using as well, just pass the vcc pin which is activating the transistor hence powering on the sensor. You should use also some resistors, for sure to drive the base, potentially on the collector/emitter depending on the transistor you are using

[ElCheekytico]

@user2684 Thanks for the confirmation. Now I'm just not sure if I have enough IO pins without wiring directly from pro mini.

@sundberg84 how many IO pins are actually available on easypcb rev10 without wiring directly from pro mini? I'm using D3 for PIR, A4/A5 for oled i2c, and D5 for DHT22. I think A0 is for battery voltage and D2 for RFM69. Maybe D6 and A1?

[sundberg84]

@ElCheekytico correct, every pin you have on the mysx connector.

[MatiasV]

@user2684 Did you experience any problems reading analog sensors that are powered via a transistor? I can not get reliable measurements from Capacitive Soil moisture Sensors when they are switched by a transistor.

[Phil Whitmarsh]

@MatiasV said in Nodemanage + EasyPCB Sleep:

@user2684 Did you experience any problems reading analog sensors that are powered via a transistor? I can not get reliable measurements from Capacitive Soil moisture Sensors when they are switched by a transistor.

@MatiasV - How are you wiring up your transistor?
Can you see the Voltage to the Sensor switching?

[Phil Whitmarsh]

@bikerMark said in Nodemanage + EasyPCB Sleep:

@sundberg84 said in Nodemanage + EasyPCB Sleep:

@ElCheekytico - even better with transistor if you know how, atleast for the higher current things

This is exactly what I'm trying to achieve these days with an Attiny. Found a way to toggle on/off with one button: http://www.technoblogy.com/show?VOO (scroll down). When OFF; ATtiny is is a 0.5uA (!) sleep.

Now I want to swicth the full 10Amps on 40V with that aw..Tiny signal.
@sundberg84 do you know how to boost the signal to a (couple of) transistor(s)?

Any advice would be highly appreciated!

I would not take too much notice of that Web Page schematics, he has drawn the Fets the wrong way around - this is on all his examples (He has mixed up the drawing of the P & N Mosfets)

[user2684]

@MatiasV Probably you would also need to wait a bit before reading after powering on the sensor. You can try adding a delay (in millis) as third argument to setPowerPins() of PowerManager so before the reading would take place, the Power Manager will wait a bit after power on and before giving control back to the sensor.

[bikerMark]

@sundberg84 thanks, prudence is needed indeed. I abandoned this scenario and now only switch the lower energetic part of the bike.