Powering a sensor with digital out

hozze

@TheoL I have two pro mini's. I measured the voltage across a output pin ( HIGH ) and GND and it gives me near 5V on one and near 3.3V on another .So it looks as if I do have 5V pro mini.

I have tried few other sketches on both, seems they are working fine, I face the specific issue only when including the Mysensor.h library. I will give it a try on a nano that I have and see what happens.

TheoL

@hozze It was just a guess. I once compiled a sketch for a 5V and uploaded it to a ProMini 3.3V. Took me a while before I noticed my mistake. I just didn;t understand why my Arduino couldn't control my relay boards ;-)

hozze

@TheoL :smiley: me too learning things the hard way.

Thanks for all the pointers that you guys are giving . Looks as if I'm in the right place and with a great community,

Let me tinker a bit more and see if I can get somewhere, if anyone can give any further info kindly do.

Boots33

@hozze You should enable debugging at the top of your sketch with

// Enable debug prints to serial monitor
#define MY_DEBUG

and check the serial monitor to see if the radio is initialising . Maybe the loop part of the program will not run if this does not happen. That could be why commenting out the #include <MySensors.h> allows it to work.

You might also use wait instead of delay

hozze

@Boots33 , I enabled MY_DEBUG. Sorry if I sound stupid. I have connected the pro mini to computer with USB serial CP2102 for programming/serial debug , at the same time can I power the pro mini + Radio with an external power supply 3.3V ?

I did something similar with a ATTINY85 few days back and bricked it :cry: ( Connected it to USB and same time powered it )

mfalkvidd

@hozze connect gnd from the serial adapter AND the external power supply to gnd on the Arduino. Connect + on the external adapter to the pin you normally use (vcc or raw). Do not connect + from the serial adapter. That's it.

Boots33

@hozze The whole purpose of a good forum is for people to share ideas and knowledge. So never be worried about asking questions. :)

hozze

Thanks guys, I will check this out.

hozze

Was away from arduino for over a week with regular job. Tested the code with debug on a new arduino pro mini 3.3v 8Mhz and the below is the output ( please note that the values getting send are random values , i'm still not able to power the sensor with digital Pin )

TSP:MSG:SEND 1-1-0-0 s=255,c=3,t=15,pt=6,l=2,sg=0,ft=0,st=ok:0100
TSP:MSG:SEND 1-1-0-0 s=255,c=0,t=17,pt=0,l=5,sg=0,ft=0,st=ok:2.0.0
TSP:MSG:SEND 1-1-0-0 s=255,c=3,t=6,pt=1,l=1,sg=0,ft=0,st=ok:0
TSP:MSG:READ 0-0-1 s=255,c=3,t=15,pt=6,l=2,sg=0:0100
TSP:MSG:SEND 1-1-0-0 s=1,c=0,t=35,pt=0,l=0,sg=0,ft=0,st=ok:
TSP:MSG:SEND 1-1-0-0 s=255,c=3,t=11,pt=0,l=10,sg=0,ft=0,st=ok:SoilSensor
TSP:MSG:SEND 1-1-0-0 s=255,c=3,t=12,pt=0,l=3,sg=0,ft=0,st=ok:0.1
Request registration...
TSP:MSG:SEND 1-1-0-0 s=255,c=3,t=26,pt=1,l=1,sg=0,ft=0,st=ok:2
TSP:MSG:READ 0-0-1 s=255,c=3,t=27,pt=1,l=1,sg=0:1
Node registration=1
Init complete, id=1, parent=0, distance=1, registration=1
TSP:MSG:SEND 1-1-0-0 s=1,c=1,t=37,pt=2,l=2,sg=0,ft=0,st=ok:786
TSP:MSG:SEND 1-1-0-0 s=1,c=1,t=37,pt=2,l=2,sg=0,ft=0,st=ok:503
TSP:MSG:SEND 1-1-0-0 s=1,c=1,t=37,pt=2,l=2,sg=0,ft=0,st=ok:410
TSP:MSG:SEND 1-1-0-0 s=1,c=1,t=37,pt=2,l=2,sg=0,ft=0,st=ok:425
TSP:MSG:SEND 1-1-0-0 s=1,c=1,t=37,pt=2,l=2,sg=0,ft=0,st=ok:461
TSP:MSG:SEND 1-1-0-0 s=1,c=1,t=37,pt=2,l=2,sg=0,ft=0,st=ok:539
TSP:MSG:SEND 1-1-0-0 s=1,c=1,t=37,pt=2,l=2,sg=0,ft=0,st=ok:507
TSP:MSG:SEND 1-1-0-0 s=1,c=1,t=37,pt=2,l=2,sg=0,ft=0,st=ok:392

Looks fine for me , still I can't turn a digital pin On :disappointed:

Boots33

@hozze It really should be working. I tried your original above and with a led connected to pin 5 it turns on when the code is run

try the code below with some serial prints to see what happens

// Enable debug prints to serial monitor
#define MY_DEBUG
#define MY_NODE_ID 150  // node id 
#define MY_RADIO_NRF24  // enabling support for NRF radio module

#define NODE_ID 1  // sensor id
#define SENS_ON 5
#define VAL_PROBE A0
#include <MySensors.h>
#define POWER_ON 1  //  value to write to turn on sensor
#define POWER_OFF 0 //  value to write to turn off sensor
MyMessage msg(NODE_ID, V_LEVEL); // constructing the msg

void setup()
{
  pinMode(SENS_ON, OUTPUT);
}

void presentation()
{
  present(NODE_ID, S_MOISTURE);  // presenting the sensor
  sendSketchInfo("SoilSensor", "0.1"); //meta data
}

void loop()
{


  digitalWrite(SENS_ON, POWER_ON);
  Serial.print("Sensor Power on pin "); Serial.print(SENS_ON); Serial.print(" is..."); Serial.println((POWER_ON));
  wait(1000); // To check the input voltage of pin 2
  int moisture = analogRead(VAL_PROBE); //measuring the moisture
  send(msg.set(moisture));  // sending the data
  digitalWrite(SENS_ON, POWER_OFF); // turn it off
  Serial.print("Sensor Power on pin "); Serial.print(SENS_ON); Serial.print(" is..."); Serial.println((POWER_OFF));

  wait(1000);
}

I get an output like this below and the led flashes on and off at 1 second intervals. Maybe try just a led with a 200 to 300 ohm resistor on pin 5 to see what is happening. could the moisture sensor be drawing more than the arduino can give?

TSP:MSG:SEND 150-150-0-0 s=255,c=3,t=6,pt=1,l=1,sg=0,ft=1,st=ok:0
TSP:MSG:READ 0-0-150 s=255,c=3,t=6,pt=0,l=1,sg=0:M
TSP:MSG:SEND 150-150-0-0 s=1,c=0,t=35,pt=0,l=0,sg=0,ft=0,st=ok:
TSP:MSG:SEND 150-150-0-0 s=255,c=3,t=11,pt=0,l=10,sg=0,ft=0,st=ok:SoilSensor
TSP:MSG:SEND 150-150-0-0 s=255,c=3,t=12,pt=0,l=3,sg=0,ft=0,st=ok:0.1
Request registration...
TSP:MSG:SEND 150-150-0-0 s=255,c=3,t=26,pt=1,l=1,sg=0,ft=0,st=ok:2
TSP:MSG:READ 0-0-150 s=255,c=3,t=27,pt=1,l=1,sg=0:1
Node registration=1
Init complete, id=150, parent=0, distance=1, registration=1
Sensor Power on pin 5 is...1
TSP:MSG:SEND 150-150-0-0 s=1,c=1,t=37,pt=2,l=2,sg=0,ft=0,st=ok:511
Sensor Power on pin 5 is...0
Sensor Power on pin 5 is...1
TSP:MSG:SEND 150-150-0-0 s=1,c=1,t=37,pt=2,l=2,sg=0,ft=0,st=ok:313
Sensor Power on pin 5 is...0
Sensor Power on pin 5 is...1
TSP:MSG:SEND 150-150-0-0 s=1,c=1,t=37,pt=2,l=2,sg=0,ft=0,st=ok:254
Sensor Power on pin 5 is...0
Sensor Power on pin 5 is...1
TSP:MSG:SEND 150-150-0-0 s=1,c=1,t=37,pt=2,l=2,sg=0,ft=0,st=ok:326
Sensor Power on pin 5 is...0
Sensor Power on pin 5 is...1
TSP:MSG:SEND 150-150-0-0 s=1,c=1,t=37,pt=2,l=2,sg=0,ft=0,st=ok:235
Sensor Power on pin 5 is...0
Sensor Power on pin 5 is...1

hozze

I'm stupid ! @Boots33 the debug info saved me. With debug info I came to notice that the sketch goes into loop part only if the gateway is also connected and available. Stupid me was doing the pin checks just by connecting the sensor and keeping the gateway disconnected , when I had the gateway connected I didn't bother to check the pin out, I was going in the same loop and wasting my and all your valuable time.

Thanks for all your assistance people, you guys are awesome.

Boots33

Great to hear you got it going, and don't worry I am sure everyone here ( including me) has there own moments they would rather forget when it comes to writing code. :)

xydix

This sounds like a really good idea.
Can I use this to power like a DS18B20 tempsensor. Would this save power and give my battery powered sensors extended battery life?

bjacobse

@xydix
Arduino using Atmega can supply max 40mA per pin, and in total max 100mA.
DS18B20 seems to use max 1,5mA
so yes this will work
After searching on the net.
https://github.com/nathanchantrell/TinyTX/blob/master/TinyTX_DS18B20/TinyTX_DS18B20.ino

The part for the power on, read, power off is below (taken from the above link):

void loop() {

digitalWrite(ONE_WIRE_POWER, HIGH); // turn DS18B20 sensor on

//Sleepy::loseSomeTime(5); // Allow 5ms for the sensor to be ready
delay(5); // The above doesn't seem to work for everyone (why?)

sensors.begin(); //start up temp sensor
sensors.requestTemperatures(); // Get the temperature
tinytx.temp=(sensors.getTempCByIndex(0)*100); // Read first sensor and convert to integer, reversed at receiving end

digitalWrite(ONE_WIRE_POWER, LOW); // turn DS18B20 off

Powering a sensor with digital out

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