Disconnect power lines

[ecabanas]

Hi all

I have a Sipy and I put a deepsleep every 15 minutes. I have a ds18b temp sensor and I saw that may be the energy is on when the pycom is in deep sleep. There is any option to power the lines via pin? I saw an example but I don't know if this line has a mosfet or something that cuts the power in deep

Thanks'

Eduard

[robert-hh]

@ecabanas You cannot use P0, because that one is the RX pin of the UART0. Use another pin.

[ecabanas]

@ecabanas
now is working on pin8

;-)

[ecabanas]

@robert-hh

Hi,

Thanks for your answer and sorry about the delay but I was closing year.

I connected to pin0 with the following code:

from machine import Pin
import utime
import time
import socket
import pycom
import machine



#Power the sensor
pinPwr = Pin('P0', mode=Pin.OUT)
pinPwr(True)
pycom.heartbeat(False)
pycom.rgbled(0x00ff00)
time.sleep(2)
pinPwr(False)
machine.deepsleep(1000*10)

But I only have 2.20volts, and the minimum for the sensors are 3.3V, you know why I only have 2,2vlt?

Thanks

Eduard

[kjm]

@robert-hh unreal!

[robert-hh]

@kjm Were these all genuine parts or also some fakes. You sure know this post: https://github.com/cpetrich/counterfeit_DS18B20

[kjm]

@robert-hh One thing I discovered Rob is not all DS18B20s are created equal. I found my collection of several dozen, acquired over as many years of tinkering, fell into 3 groups of standby power consumption. Group1, standby power <1uA, group2 0-1uA & group3 50uA.

[robert-hh]

@ecabanas A good way avoiding that is to switch the GPIO pin to 0 or to input mode before starting deepsleep. That stops potential leakage. The current drawn by the ds18B20 is ~1 mA in active mode. So suppying it from a GPIO is not a problem.
Take care to connect the pull-up resistor for the data line to the same source.

[ecabanas]

Hi @robert-hh

Do you know if powering via gpio, will no have power leak? I designed a board for arduinos 2 years ago and the only way to avoid power leaks is using mosfets...

Thanks again

[robert-hh]

@ecabanas you can power the ds18b20 from a gpio pin, which you switch on and off as required.