Vegetable sensor stick

Prototype setup done!

These are the sensors that I've been experimenting with on my breadboard:

• Air humidity and temperature
• DHT11
• Soil moisture using capacitance measurements
• Internal uC
• Barometer 
• BMP085
• Color and amount of Light 
• ADJD-S311-CR999

Prototype setup. Mounted in my propagator

COSM - Internet of Things

I've successfully gathered a week of data to the online graphing service of Cosm (internet of things / Cloud service).

You can see the day/night rhythm, and since we are still in the winter here in Netherlands, there isn't much bright daylight. Also the humidity indicator shows when I mounted the clear plastic cap over my vegetables, it caused a rapid increase of the humidity.
Please note that in the image above, the SoilMoisure, SoilTemperature and CO2 was still under development. That's why there is no (complete) line. See the complete, real-time data here https://cosm.com/feeds/119538.

Making it more serious

Now it is time to move the prototype to the next level. I want to make a PCB out of it. Since I've currently got 10 places I want to monitor, I want to keep the costs for each unit low but very flexible/universal.

I am thinking about

• Battery powered (3xAAA or 1x CR2032 coin cell)
• Soil moisture area directly mounted on the PCB
• All the sensors currently attached to the PCB
• Have a voltage output that represents the value of the soil and humidity
• analog output between [0v...3v] for soil moisure (at least 12bit resolution)
• analog output between [0v...3v] for humidity (at least 8bit resolution)
• Have a serial output pins that broadcast data
• Keep the Arduino bootloader so it will be very easy for others to make changes
• but to save costs, remove the USB to UART. 
• Publish source and hardware to google project as open source
• Capacitance button to pair the device to the mainboard
• LDR for light measurement for cheaper versions (PCB will be AND not OR)

The very basic version of the PCB should have at least the Soil moisture measurements for less than 15 euro. Lets see if I can keep that thought. Also thinking of a good name for the project, hmmm.. Vegetable SensorStick ? EEO SensorStick? Well.. that is for later. First make the PCB :)

Idea for the DAC output of the soil and humidity outputs

Today taken pictures of the Propagator

Personal note:

• CO2
• Humidity
• Temp Ambient
• Temp Soil
• Soil moisture
• Barometer 
• Light resistor
• Color / light sensor

Arduino capacitance measurement

I`m in the need to measure my plants soil moisture. I've read a lot about the possible options to measure soil moisture like sensing resistance or capacitance. Using the resistance measurement, the probes are sensitive to corrosion due electrolyse so I want to give it a go to measure the capacitance and see what happens.

Here is what I did for the hardware part on my Arduino nano:

This is the sketch I used

#include

// analog defines

// defines for setting and clearing register bits

#ifndef cbi

#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))

#endif

#ifndef sbi

#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))

#endif

void setup() {

  Serial.begin(9600);

  Serial.println("StartUp\n");

  // analog init

    analogReference(INTERNAL);

  // set prescale to 16

  sbi(ADCSRA,ADPS2) ;

  cbi(ADCSRA,ADPS1) ;

  cbi(ADCSRA,ADPS0) ;

    

  Serial.println("Init OK \n");

}

void capMeasurement(void)

{

  uint16_t sensorValue = 0;  // variable to store the value coming from the sensor

  static uint16_t sensorHistory;

  sensorValue = 0;

  

  for(int count = 16; count != 0; count--)

  {

    // note that default Wire.h was to slow to use, so these are direct MCU commands.

    // should make a Arduino library from it.

    //pinMode(A0, OUTPUT);

    //pinMode(A1, OUTPUT);

    // the above commented text is done with direct MCU register commands (faster)

    DDRC = DDRC | ~B11111100; // make A0/A1 output

    

    //digitalWrite(A0, HIGH);

    //digitalWrite(A1, HIGH);

    // the above commented text is done with direct MCU register commands (faster)

    PORTC = PORTC | B00000011; //charge external Cx

    delayMicroseconds(10); // let the Cx charge 10uS

    

    //pinMode(A1, INPUT); 

    DDRC = DDRC & B11111101; // make A1 input

    

    //digitalWrite(A0, LOW);

    PORTC = PORTC & B11111100; // transfer charge to C1 (by grounding C1)

    

    // read the value from the sensor:

    sensorValue += analogRead(A1); 

  }

  PORTC = PORTC | ~B11111100; // done 

  Serial.print(" cap=");

  Serial.print(sensorValue);

}

void loop() {

  capMeasurement();

  Serial.println();

}

Arduino Nano atmega328p low power usage (sleep, etc)

Power usage Arduino Nano w/ Mega328p
*Please note, having the MK2 programmer connected = + 20uA
*Please note, I`m using cheap china multimeter.

3400uA @
-removed 7805 lin. psu
-mega running at ext. clock (original bootloader / fuses Arduino Nano)


680uA @ conditions:
-removed 7805 lin. psu
-mega running at ext. clock (original bootloader / fuses Arduino Nano)
-USB not connected.
-PSU @ 4.8vDC

-mega:  set_sleep_mode(SLEEP_MODE_PWR_DOWN);


186uA @ conditions
-PSU @ 4.8vDC
-mega:  set_sleep_mode(SLEEP_MODE_PWR_DOWN);

Ayyy.. time is up for today, wife is calling me... to be continued eh.. :)

Measuring growing vegetables with internet of things...

I started to measure environment variables like; temperature, barometer, hygrometer, light brightness, dominant colors and much more and report it online.

Here you can see my real-time demo: https://cosm.com/users/willyp. Please note that there are moments that I am upgrading the devices. Today I am starting to make the setup more suitable for battery operation. I`m implementing processor sleep functions and disabling external devices to conserve energy. I want to have the sensor transmitter working on a double CR2032 battery for at least a year long.

Currently in the unit there are tomatoes, paprika, carrots and beans.

I am still alive!

Wow, I looked at my blogspot account and mentioned that my last blog was over 2 years ago already!!!

Looked back at the last two years, I've got quite a lot of reasons why I did not post anymore to this blog: I really had no time left to do that!. Past years, I've lost my dad, bought a new home (and completely changed it), finished my study and much more.

But since some time I had some spare time left in the weekends so I started to pickup my hobbies again... :) .
I'will keep you posted!

By the way, I finished my KeaDrone project. It has changed a bit from helicopter to a Quadcopter design but I have it flying!! :D Already have some great pictures taken with the copter from some altitude..... :D