Office plant monitor

[openhardware.io]

https://www.openhardware.io/view/123/Office-plant-monitor

[scalz]

@carlierd excellent, it looks very nice

[hek]

So nice!

[Nca78]

Very nice indeed !
Do you have an idea of the battery life on this sensor ? Why not change to 1MHz to allow the voltage to go down to 1.9 or 1.8 V ?

[mfalkvidd]

@Nca78 from the description:
Expected duration more than 2 years for the CR2032 and about 3.5 with the two AA (power consumption less than 5uA during sleep time; measured using a uCurrent Gold).

[carlierd]

@Nca78 Like @mfalkvidd wrote, the expected life duration is greater than 2 years. But it's just theory. My first node (on 2*AA) was started several weeks ago and the battery level did not change. So I am confident

I measure the power consumption when working at 1 MHz and there was no difference between 1 or 8 MHz. As I have to decrease the transmission speed at 1 MHz, I got some issues. The main was probably with the signing feature.

[Nca78]

@carlierd you cannot compare the behavior of AA batteries and CR2032. Button cells have a high internal resistance, you can't draw much current from them else the voltage drops very quickly. The more current you draw the more you lose in heat because of this internal resistance, the solution is to use a big capacitor to provide the current, then you lose energy because capacitor has a current leak, but usually it's better than what you lose with internal resistance.

Maybe your 100uF is doing that job if data sending is quick enough, but at 8MHz and the voltage drop when sending you might already be very close to brown out level (or crash level if you have disabled brown out), you should check the voltage just after sending and not before to have an idea.

Look at the difference in voltage level in the second "pulse mode" graph on page 2, which I believe uses a similar pulse current draw than your board when you transmit, after only 50mAh of capacity used the voltage is down to 2.4V...
http://data.energizer.com/PDFs/cr2032.pdf

[carlierd]

Interesting !
I will check in few weeks the result. There is several capacitors to help the stability maybe it could be enough. If it's not the case I will replace the CR2032 by 2 * AAA.

[scalz]

@Nca78 you can have brownout if the battery is near end of life and nothing has been designed to handle a bit the internal res. but with a fresh a coincell and some capa, you can do some chain tx but that's not the best for the battery life.

The only case where i had issue with brownout at startup, plus it was a fresh coincell was with a crappy ali coincell batt!! very bad quality! now I'm using only good quality coincell like duracell, varta, maxell.. and that's day and night

@carlierd If you're interested this doc explains very well the capacitor calc etc... http://www.ti.com.cn/cn/lit/wp/swra349/swra349.pdf

• capa ideally calculated/estimated (on mine I have 200uF, plus others for sensors, radio is 86uA etc..) and after multiple msg presentation on frsh coincell i don't fall under 2.85 (voltage starts 3.05V) because I can't recover voltage during this period.
  Hopefully a transmit is not 1sec! More something like says 30+ ms (depending if signing is needed, ack, retries.. etc). To not break capa benefits, it's better to sleep between tx during chains..to recover voltage and optimize battery life. Sleeping 200ms can be enough
• For the capa leakage, it depends of capa. common good quality ceramic have not those leakage (few nano). Sure on this design it's not a ceramic.
• You're right at runtime 1Mhz consumes less than 8Mhz; mA vs thousands uA. But at 1Mhz everything is slower, comms too (I mean code execution). During deep sleep, there is no difference in power consumption. Oscillator is stopped so mhz does not mean. Note: at 8Mhz you can wake in few uA, at 1Mhz it's slower of course.

[NeverDie]

I wonder whether a higher capacity coincell, like maybe a CR2450 (620mah) or a CR2477 (1000mah capacity), might give you the pulse current you need without needing a capacitor, thus avoiding leakage losses? Plus maybe you wouldn't need to change it as often.

[scalz]

sure 2450/77 would be better. 2477 is a bit expensive.
but not sure if those coincell would be better without capacitor (I mean in the long term), looking at coincells datasheets.. which are always given for x kohms load.
leakage current for ceramic common quality capacitor is in nA range (hopefully), so i think it's better to have it buffering to help the coincell (still for the long term, or at a momemt it won't be enough strong). if alka, there would no need..
that's imho.

[Nca78]

Stop wondering. I tried with 2477 cells and it was not much better than 2032 without capacitor

[carlierd]

@scalz : I missed your reply ! Interesting withe paper !

@scalz said:

@Nca78 you can have brownout if the battery is near end of life and nothing has been designed to handle a bit the internal res. but with a fresh a coincell and some capa, you can do some chain tx but that's not the best for the battery life.

The only case where i had issue with brownout at startup, plus it was a fresh coincell was with a crappy ali coincell batt!! very bad quality! now I'm using only good quality coincell like duracell, varta, maxell.. and that's day and night

@carlierd If you're interested this doc explains very well the capacitor calc etc... http://www.ti.com.cn/cn/lit/wp/swra349/swra349.pdf

• capa ideally calculated/estimated (on mine I have 200uF, plus others for sensors, radio is 86uA etc..) and after multiple msg presentation on frsh coincell i don't fall under 2.85 (voltage starts 3.05V) because I can't recover voltage during this period.
  Hopefully a transmit is not 1sec! More something like says 30+ ms (depending if signing is needed, ack, retries.. etc). To not break capa benefits, it's better to sleep between tx during chains..to recover voltage and optimize battery life. Sleeping 200ms can be enough
• For the capa leakage, it depends of capa. common good quality ceramic have not those leakage (few nano). Sure on this design it's not a ceramic.
• You're right at runtime 1Mhz consumes less than 8Mhz; mA vs thousands uA. But at 1Mhz everything is slower, comms too (I mean code execution). During deep sleep, there is no difference in power consumption. Oscillator is stopped so mhz does not mean. Note: at 8Mhz you can wake in few uA, at 1Mhz it's slower of course.

[scalz]

@carlierd yep, this doc inspired me too, plus coincell datasheets,. I use mega-pile for sourcing batt and they have lot of battery datasheet.
I have also recently designed few small sensors I need to put on a panel now

• moisture+temp
• moisture+salinity/conductivity+temp

[jkarras]

How did you source the probe portion of the sensor?

[tomtastic]

Could this be used with a capacitative soil sensor to avoid corrosion of the sensor over time ?

[NeverDie]

@tomtastic said in Office plant monitor:

Could this be used with a capacitative soil sensor to avoid corrosion of the sensor over time ?

Yes. Do you have one in mind?

[tomtastic]

@NeverDie Something like https://8f26945f-a-62cb3a1a-s-sites.googlegroups.com/site/drxzcl/capsensor.brd ?

[NeverDie]

@tomtastic said in Office plant monitor:

@NeverDie Something like https://8f26945f-a-62cb3a1a-s-sites.googlegroups.com/site/drxzcl/capsensor.brd ?

I don't know whether it's better or worse, but the Chirp! is a capacitive soil moisture probe that has been around for awhile and is, IIRC, atmel based. It used to sell for around $15, but I just noticed that you can buy it for less than $5 from a number of ebay sellers, such as:
http://www.ebay.com/itm/182446660427

Historically, one problem with PCB probes has been that over time water intrudes into the PCB and throws off the calibration. Not sure if there's a solution for that problem, though it seems like one should exist.

[Edit: I see that the original author of the Chirp does have some suggestions now regarding ways to waterproof it: https://www.tindie.com/products/miceuz/i2c-soil-moisture-sensor/ ]

BTW, the Chirp is open source: https://wemakethings.net/chirp/

There's also this, which I'm not familiar with: https://www.aliexpress.com/item/DFRobot-Capacitive-Analog-Soil-Moisture-Sensor-3-3-5-5V-Corrosion-Resistant-with-Gravity-3-Pin/32574020064.html?spm=2114.01010208.3.2.P99ddH&ws_ab_test=searchweb201556_0&aff_platform=aaf&cpt=1496178932140&sk=e2Vzr3v&aff_trace_key=17f48f5bf06b4b5daa3c5b3d8442dc7c-1496178932140-02358-e2Vzr3v

You might be inbterested in this thread: https://forum.mysensors.org/topic/990/soil-tensiometer-sensor-network

[NeverDie]

@tomtastic

Anyhow, the probe you referenced looks a lot like this one: http://zerocharactersleft.blogspot.com/2011/11/pcb-as-capacitive-soil-moisture-sensor.html

As an aside, people seem happy with the Vegetronix probe, up until its PCB suffers water intrusion. The asking price is rather high though. If I knew how to, I'd make one of those and simply waterproof it better.

[tomtastic]

@NeverDie The person behind 'Chirp' actually left a comment in your last link (zerocharactersleft). He posts an interesting link back to his own studies too : https://wemakethings.net/2012/09/26/capacitance_measurement/

[NeverDie]

@tomtastic said in Office plant monitor:

@NeverDie The person behind 'Chirp' actually left a comment in your last link (zerocharactersleft). He posts an interesting link back to his own studies too : https://wemakethings.net/2012/09/26/capacitance_measurement/

Thanks for the link.

For the best results, running the square wave at 80Mhz or faster seems to be important. That's what vegetronix does. Now, the good news is that the clock on an ESP8266 can supply that frequency.. However, all this analog circuitry is beyond my purview, so I inevitably hit a wall with that. Is that something you (or someone reading this) knows how to do? For instance, I don't know whether the chirp guy's circuit that you linked to works as-is at 80Mhz, or whether it requires modification. If the latter, that's where I get stuck not knowing what to do.

[NeverDie]

@tomtastic

It turns out that the circuit the Chirp guy described in the link that you provided is, in fact, what is built into Chirp: https://wemakethings.net/2013/06/07/chirp-plant-watering-alarm/

None of his calculations make reference to frequency, so maybe (?) you could hook up the circuit to 80Mhz and it would "just work." I suppose the switching speed of those transistors might be a factor. I have no insight into that, but it would probably be easy for someone to test. IIRC, the higher frequency makes a capacitive soil moisture sensor much less influenced by soil characteristics other than moisture, so it's really necessary to have that in order to make a good probe.

[Edit: What you don't want is a soil moisture probe that requires frequent manual re-calibration. Ordinary conductive probes all have that as an inherent problem. Hence the hunt for a worthwhile capacitive soil moisture sensor.] ]

[NeverDie]

Completely unrelated, but I just noticed this:
https://www.aliexpress.com/item/SHT10-SHT11-SHT15-waterproof-sensor-case-temperature-and-humidity-protective-cover-soil-sensor-cover-40mm-15mm/32575966509.html?spm=2114.8153822.cb0001.16.lITM8E&scm=1007.13409.76764.0&pvid=0acc75b7-138d-456f-a5bf-5147c2ea763f&tpp=1
So with that, you could just use a regular humidity sensor inside it to judge soil moisture. Pretty cool, yes? Not sure how big it is, but maybe you could even fit your entire sensor node inside it.

[Nca78]

@NeverDie said in Office plant monitor:

Completely unrelated, but I just noticed this:
https://www.aliexpress.com/item/SHT10-SHT11-SHT15-waterproof-sensor-case-temperature-and-humidity-protective-cover-soil-sensor-cover-40mm-15mm/32575966509.html?spm=2114.8153822.cb0001.16.lITM8E&scm=1007.13409.76764.0&pvid=0acc75b7-138d-456f-a5bf-5147c2ea763f&tpp=1
So with that, you could just use a regular humidity sensor inside it to judge soil moisture. Pretty cool, yes? Not sure how big it is, but maybe you could even fit your entire sensor node inside it.

One of the local shops I buy electronic parts from has those. Unfortunately it's too small to house an entire sensor.

[NeverDie]

This thread also has a lot of good background information and links about capacitive soil moisture sensors: https://lowpowerlab.com/forum/general-topics/using-capsense-to-measure-soil-moisture/

[NeverDie]

It might be that one could more or less whack an 80Mhz frequency oscillation chip into the Chirp circuit: https://www.digikey.com/product-detail/en/linear-technology/LTC6905CS5-80-TRMPBF/LTC6905CS5-80-TRMPBFCT-ND/810907

[scalz]

i agree with @NeverDie
It's better to use high freq for a reliable soil moisture, regarding soils, calibration etc. and some studies argues even more than 200Mhz. but with 80-100 it's nice.
I have one design at this freq, non corrosive design, and not same as chirp though, but can't really help you (mine is not open yet, and busy on others projects).
Regarding the chirp design, I think it may need an opamp for better results regarding the 1M resistor etc, and some more tuning if going high freq.

[simbic]

Trying to get this working but getting alot of errors. New to this so bear with me.

In file included from C:\...\Arduino\libraries\Moisture_sensor\Moisture_sensor.ino:55:0:

C:\...\Arduino\libraries\MySensors/MyTransportRFM69.h:31:1: error: expected class-name before '{' token

 { 

 ^

C:\...\Arduino\libraries\MySensors/MyTransportRFM69.h:33:36: error: 'RFM69_FREQUENCY' was not declared in this scope

  MyTransportRFM69(uint8_t freqBand=RFM69_FREQUENCY, uint8_t networkId=RFM69_NETWORKID, uint8_t slaveSelectPin=RF69_SPI_CS, uint8_t interruptPin=RF69_IRQ_PIN, bool isRFM69HW=false, uint8_t interruptNum=RF69_IRQ_NUM);

                                    ^

C:\...\Arduino\libraries\MySensors/MyTransportRFM69.h:33:71: error: 'RFM69_NETWORKID' was not declared in this scope

  MyTransportRFM69(uint8_t freqBand=RFM69_FREQUENCY, uint8_t networkId=RFM69_NETWORKID, uint8_t slaveSelectPin=RF69_SPI_CS, uint8_t interruptPin=RF69_IRQ_PIN, bool isRFM69HW=false, uint8_t interruptNum=RF69_IRQ_NUM);

                                                                       ^

In file included from C:\...\Arduino\libraries\Moisture_sensor\Moisture_sensor.ino:56:0:

C:\...\Arduino\libraries\MySensors/MySigningAtsha204Soft.h:55:1: error: expected class-name before '{' token

 { 

 ^

C:\...\Arduino\libraries\MySensors/MySigningAtsha204Soft.h:62:25: error: 'MY_RANDOMSEED_PIN' was not declared in this scope

   uint8_t randomseedPin=MY_RANDOMSEED_PIN);

                         ^

Moisture_sensor:83: error: call to 'MySigningAtsha204Soft::MySigningAtsha204Soft(bool, uint8_t)' uses the default argument for parameter 2, which is not yet defined

 MySigningAtsha204Soft signer;

                       ^

Moisture_sensor:84: error: 'MyHwATMega328' does not name a type

 MyHwATMega328 hw;

 ^

Moisture_sensor:85: error: call to 'MyTransportRFM69::MyTransportRFM69(uint8_t, uint8_t, uint8_t, uint8_t, bool, uint8_t)' uses the default argument for parameter 1, which is not yet defined

 MyTransportRFM69 transport;

                  ^

Moisture_sensor:85: error: call to 'MyTransportRFM69::MyTransportRFM69(uint8_t, uint8_t, uint8_t, uint8_t, bool, uint8_t)' uses the default argument for parameter 2, which is not yet defined

Moisture_sensor:86: error: 'MySensor' does not name a type

 MySensor node(transport, hw, signer);

 ^

C:\...\Arduino\libraries\Moisture_sensor\Moisture_sensor.ino: In function 'void setup()':

Moisture_sensor:112: error: 'node' was not declared in this scope

   node.begin();

   ^

C:\...\Arduino\libraries\Moisture_sensor\Moisture_sensor.ino: In function 'void loop()':

Moisture_sensor:163: error: 'node' was not declared in this scope

   node.send(msgMoisture.set((moistureLevel + oldMoistureLevel) / 2.0 / 10.23, 1));

   ^

C:\...\Arduino\libraries\Moisture_sensor\Moisture_sensor.ino: In function 'int readMoisture()':

Moisture_sensor:200: error: 'node' was not declared in this scope

   node.sleep(STABILIZATION_TIME);

   ^

exit status 1
call to 'MySigningAtsha204Soft::MySigningAtsha204Soft(bool, uint8_t)' uses the default argument for parameter 2, which is not yet defined

I have looked through the code but can't seem to see what is wrong with it.

Please help

[mfalkvidd]

@simbic did you modify the sketch in any way? If so, could you please post it?

My guess would be an incomplete #define or using incompatible versions. Which version of MySensors are you using?

[simbic]

@mfalkvidd

I have assembled a copy of @carlierd 's office plant monitor since it looked kinda neat.
When I first tried to upload @carlierd 's Moisture_sensor.ino it complained that several libraries were missing.
So I started google-fu around to find them.
What was missing was:
MyTransportRFM69.h
MyTransport.h
MySigningAtsha204Soft.h
MySigning.h
MyMessage.h

aswell as drivers, that I placed in folder /utility/
ATSHA204.h
RFM69.h
sha256.h

The code is as follows. I have only pressed include mysensors' library since it complained that it was missing.

/**
 * The MySensors Arduino library handles the wireless radio link and protocol
 * between your home built sensors/actuators and HA controller of choice.
 * The sensors forms a self healing radio network with optional repeaters. Each
 * repeater and gateway builds a routing tables in EEPROM which keeps track of the
 * network topology allowing messages to be routed to nodes.
 *
 * Created by Henrik Ekblad <henrik.ekblad@mysensors.org>
 * Copyright (C) 2013-2015 Sensnology AB
 * Full contributor list: https://github.com/mysensors/Arduino/graphs/contributors
 *
 * Documentation: http://www.mysensors.org
 * Support Forum: http://forum.mysensors.org
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 * Code and idea from mfalkvidd (http://forum.mysensors.org/user/mfalkvidd).
 *
 */

/**************************************************************************************/
/* Moisture sensor.                                                                   */
/*                                                                                    */
/* Version     : 1.2.5                                                                */
/* Date        : 11/04/2016                                                           */
/* Modified by : David Carlier                                                        */
/**************************************************************************************/
/*                                ---------------                                     */
/*                            RST |             |  A5                                 */
/*                            RX  |             |  A4                                 */
/*                            TX  |   ARDUINO   |  A3                                 */
/*     RFM69 (DIO0) --------- D2  |     UNO     |  A2                                 */
/*                            D3  |             |  A1 --------- Moisture probe        */
/*            Power --------- D4  | ATMEGA 328p |  A0 --------- Moisture probe        */
/*              +3v --------- VCC |             | GND --------- GND                   */
/*              GND --------- GND |  8MHz int.  | REF                                 */
/*                            OSC |             | VCC --------- +3v                   */
/*                            OSC |             | D13 --------- RFM69 (SCK)           */
/*                            D5  |             | D12 --------- RFM69 (MISO)          */
/*                            D6  |             | D11 --------- RFM69 (MOSI)          */
/*                            D7  |             | D10 --------- RFM69 (NSS)           */
/*              LED --------- D8  |             |  D9                                 */
/*                                ---------------                                     */
/*                                                                                    */
/* +3v = 2*AA                                                                         */
/*                                                                                    */
/**************************************************************************************/


#include <SPI.h>
#include <MySensors.h>
#include <MyTransportRFM69.h>
#include <MySigningAtsha204Soft.h>


//Define functions
#define round(x) ((x)>=0?(long)((x)+0.5):(long)((x)-0.5))
#define N_ELEMENTS(array) (sizeof(array)/sizeof((array)[0]))

//Constants for MySensors
#define SKETCH_NAME           "Moisture Sensor"
#define SKETCH_VERSION        "1.2.6"
#define CHILD_ID_MOISTURE     0
#define CHILD_ID_VOLTAGE      1
#define LED_PIN               8
#define THRESHOLD             1.1     // Only make a new reading with reverse polarity if the change is larger than 10%
#define STABILIZATION_TIME    1000    // Let the sensor stabilize before reading
//#define BATTERY_FULL          3143    // 2xAA usually gives 3.143V when full
#define BATTERY_FULL          3100    // CR2032 usually gives 3.1V when full
#define BATTERY_ZERO          2340    // 2.34V limit for 328p at 8MHz
#define SLEEP_TIME            7200000 // Sleep time between reads (in milliseconds) (close to 2 hours)
const int SENSOR_ANALOG_PINS[] = {A0, A1};


//Variables
byte direction = 0;
int oldMoistureLevel = -1;

//Construct MySensors library
MySigningAtsha204Soft signer;
MyHwATMega328 hw;
MyTransportRFM69 transport;
MySensor node(transport, hw, signer);
MyMessage msgMoisture(CHILD_ID_MOISTURE, V_HUM);
MyMessage msgVolt(CHILD_ID_VOLTAGE, V_VOLTAGE);

/**************************************************************************************/
/* Initialization                                                                     */
/**************************************************************************************/
void setup()  
  {
  //Get time (for setup duration)
  #ifdef DEBUG
    unsigned long startTime = millis();
  #endif

  //Setup LED pin
  pinMode(LED_PIN, OUTPUT);
  blinkLedFastly(3);

  //Set moisutre sensor pins
  for (int i = 0; i < N_ELEMENTS(SENSOR_ANALOG_PINS); i++)
    {
    pinMode(SENSOR_ANALOG_PINS[i], OUTPUT);
    digitalWrite(SENSOR_ANALOG_PINS[i], LOW);
    }

  //Start MySensors and send the sketch version information to the gateway
  node.begin();
  node.sendSketchInfo(SKETCH_NAME, SKETCH_VERSION);

  //Register all sensors
  node.present(CHILD_ID_MOISTURE, S_HUM);
  node.present(CHILD_ID_VOLTAGE, S_MULTIMETER);

  //Setup done !
  blinkLedFastly(3);

  //Print setup debug
  #ifdef DEBUG
    int duration = millis() - startTime;
    Serial.print("[Setup duration: "); Serial.print(duration, DEC); Serial.println(" ms]");
  #endif
  }

/**************************************************************************************/
/* Main loop                                                                          */
/**************************************************************************************/
void loop()
  {
  //Get time (for a complete loop)
  #ifdef DEBUG
    unsigned long startTime = millis();
  #endif

  //Get moisture level
  int moistureLevel = readMoisture();

  //Send rolling average of 2 samples to get rid of the "ripple" produced by different resistance in the internal pull-up resistors
  //See http://forum.mysensors.org/topic/2147/office-plant-monitoring/55 for more information
  //Check if it was first reading, save current value as old
  if (oldMoistureLevel == -1)
    { 
    oldMoistureLevel = moistureLevel;
    }

  //Verify if current measurement is not too far from the previous one
  if (moistureLevel > (oldMoistureLevel * THRESHOLD) || moistureLevel < (oldMoistureLevel / THRESHOLD))
    {
    //The change was large, so it was probably not caused by the difference in internal pull-ups.
    //Measure again, this time with reversed polarity.
    moistureLevel = readMoisture();
    }

  //Store current moisture level
  oldMoistureLevel = moistureLevel;

  //Report data to the gateway
  long voltage = getVoltage();
  node.send(msgMoisture.set((moistureLevel + oldMoistureLevel) / 2.0 / 10.23, 1));
  node.send(msgVolt.set(voltage / 1000.0, 2));
  int batteryPcnt = round((voltage - BATTERY_ZERO) * 100.0 / (BATTERY_FULL - BATTERY_ZERO));
  if (batteryPcnt > 100) {batteryPcnt = 100;}
  node.sendBatteryLevel(batteryPcnt);

  //Print debug
  #ifdef DEBUG
    Serial.print((moistureLevel + oldMoistureLevel) / 2.0 / 10.23);
    Serial.print("%");
    Serial.print("   ");
    Serial.print(voltage / 1000.0);
    Serial.print("v");
    Serial.print("   ");
    Serial.print(batteryPcnt);
    Serial.print("%");
    int duration = millis() - startTime;
    Serial.print("   ");
    Serial.print("["); Serial.print(duration, DEC); Serial.println(" ms]");
    Serial.flush();
  #endif

  //Sleep until next measurement
  blinkLedFastly(1);
  node.sleep(SLEEP_TIME);
  }

/**************************************************************************************/
/* Allows to get moisture.                                                            */
/**************************************************************************************/
int readMoisture()
  {
  //Power on the sensor and read once to let the ADC capacitor start charging
  pinMode(SENSOR_ANALOG_PINS[direction], INPUT_PULLUP);
  analogRead(SENSOR_ANALOG_PINS[direction]);
  
  //Stabilize and read the value
  node.sleep(STABILIZATION_TIME);
  int moistureLevel = (1023 - analogRead(SENSOR_ANALOG_PINS[direction]));

  //Turn off the sensor to conserve battery and minimize corrosion
  pinMode(SENSOR_ANALOG_PINS[direction], OUTPUT);
  digitalWrite(SENSOR_ANALOG_PINS[direction], LOW);

  //Make direction alternate between 0 and 1 to reverse polarity which reduces corrosion
  direction = (direction + 1) % 2;
  return moistureLevel;
  }

/**************************************************************************************/
/* Allows to fastly blink the LED.                                                    */
/**************************************************************************************/
void blinkLedFastly(byte loop)
  {
  byte delayOn = 150;
  byte delayOff = 150;
  for (int i = 0; i < loop; i++)
    {
    blinkLed(LED_PIN, delayOn);
    delay(delayOff);
    }
  }

/**************************************************************************************/
/* Allows to blink a LED.                                                             */
/**************************************************************************************/
void blinkLed(byte pinToBlink, int delayInMs)
  {
  digitalWrite(pinToBlink,HIGH);
  delay(delayInMs);
  digitalWrite(pinToBlink,LOW);
  }

/**************************************************************************************/
/* Allows to get the real Vcc (return value in mV).                                   */
/* http://provideyourown.com/2012/secret-arduino-voltmeter-measure-battery-voltage/   */
/**************************************************************************************/
long getVoltage()
  {
  ADMUX = (0<<REFS1) | (1<<REFS0) | (0<<ADLAR) | (1<<MUX3) | (1<<MUX2) | (1<<MUX1) | (0<<MUX0);
  delay(50);  // Let mux settle a little to get a more stable A/D conversion
  //Start a conversion  
  ADCSRA |= _BV( ADSC );
  //Wait for it to complete
  while (bit_is_set(ADCSRA, ADSC));

  //Compute and return the value
  uint8_t low  = ADCL;                  // must read ADCL first - it then locks ADCH
  uint8_t high = ADCH;                  // unlocks both
  long result = (high << 8) | low;
  result = 1125300L / result;           // Calculate Vcc (in mV); 1125300 = 1.1*1023*1000
  return result;                        // Vcc in millivolts
  }

I have just installed Arduino IDE, and are using the latest mysensors library 2.1.1.

Another thing it complains about is:

Invalid library found in C:\...\Arduino\libraries\Moisture_sensor: C:\...\Arduino\libraries\Moisture_sensor```

which is wierd since I have just copy+pasted it from here:
https://www.openhardware.io/view/123/Office-plant-monitor

aswell as built the sensor from there.

If you can help, I would be very glad, as I just hoped it would be smooth sailing using mysensors. Build, upload and let it work its magic.

Tack på förhand!
Simon

[mfalkvidd]

@simbic that sketch is made for MySensors 1.x so it won't work with MySensors 2.x.

You either need to convert it (guide: https://forum.mysensors.org/topic/4276/converting-a-sketch-from-1-5-x-to-2-0-x) or use/create one for 2.x, for example https://www.mysensors.org/build/moisture

[NeverDie]

@Nca78

I see now that they have expanded their selection of waterproof sensor shells:

https://www.aliexpress.com/item/2pcs-Waterproof-Temperature-and-humidity-sensor-shell-SHT10-SHT21-SHT15-shT11-sht20-SHT75-sensor-protective-sleeve/32725766858.html?spm=2114.10010108.1000013.6.PVGRb3&traffic_analysisId=recommend_2088_3_81019_new2&scm=1007.13339.81019.0&pvid=b9edd7ff-9069-4c39-be95-b2d3ca8bdf17&tpp=1

https://www.aliexpress.com/item/2pcs-YS1560J-Temperature-and-humidity-sensor-shell-Waterproof-temperature-sensor-protective-cover-SHT10-SHT15-SHT20/32725840346.html?spm=2114.10010108.1000013.25.PVGRb3&traffic_analysisId=recommend_2088_13_81019_new2&scm=1007.13339.81019.0&pvid=b9edd7ff-9069-4c39-be95-b2d3ca8bdf17&tpp=1

https://www.aliexpress.com/item/TM16-115-temperature-and-humidity-sensor-protective-cover-waterproof-SHT10-SHT11-SHT20-SHT21-SHT15-SHT75-sensor/32578099865.html?spm=2114.10010108.1000013.10.gZI6yC&traffic_analysisId=recommend_2088_5_82199_new&scm=1007.13339.82199.0&pvid=3cc09c58-99e7-4a67-834a-3313c87ab573&tpp=1

Perhaps one of those might be big enough? Or, if not, perhaps it could be joined onto a larger waterproof cavity, and just the sensor itself goes into it? Unfortunately for me, the parts appear to be metric. However, maybe a search would yield some kind of metric-to-imperial union, at which point I could then leverage cheap local parts from Home Depot or the like, to fabricate a larger cavity for the rest of a wireless mote.

On the face of it, it seems plausible. It's main virtue is simplicity. Not sure what the failure modes are, or how they might be avoided if there are any. Plainly, you don't want to use components which might rust or otherwise corrode from humidity. Probably my biggest worry would be the possibility of condensate forming on the humidity sensor and skewing results until it evaporated. However, a sensor heater, such as some sensors (e.g. si7021: https://www.aliexpress.com/item/Industrial-High-Precision-Si7021-Humidity-Sensor-with-I2C-Interface-for-Arduino/32524005324.html?spm=a2g0s.13010208.99999999.350.t9NHvJ ) already have, might remedy that if it were to occur.

Has anyone tried either one of the above or anything similar? For instance, perhaps wrapping a mote in Tyvek and sealing the seam with Dupont housewrap tape would work just as well.

[Nca78]

@NeverDie they are all very small inside (5-6mm) so are only suitable for very thin PCB with SMD version of the sensor, even the breakout of si7021 that you linked is too big.

[NeverDie]

@Nca78
Golly, even an nRF52832 chip all by its lonesome self is bigger than 5-6mm. Those shells must be intended for just the sensor and nothing but the sensor (except maybe connecting wires). That would explain the presence of gland seals on some of them, such as:

https://www.aliexpress.com/item/Temperature-and-humidity-sensor-jacket-shell-protective-cover-waterproof-SHT10-SHT15-SHT20/32785090319.html?spm=2114.10010108.1000014.6.oDKhCV&traffic_analysisId=recommend_3035_null_null_null&scm=1007.13338.80878.000000000000000&pvid=2f02fcf9-5f96-485c-b076-6d892d6d2ae5&tpp=1
or
https://www.aliexpress.com/item/100pcs-lot-Free-shipping-SMD-resettable-fuse-SMD1206P150TF-60-1206-1-5A-1500MA-60V-PPTC/32422603296.html?spm=2114.search0104.3.126.qYG2gx&ws_ab_test=searchweb0_0,searchweb201602_5_10152_10065_10151_10068_10130_10084_10083_10119_10080_10082_10081_10110_10178_10136_10137_10111_10060_10112_5360018_10113_10155_10114_10154_438_10056_10055_10054_10182_10059_100031_10099_10078_10079_10103_10073_10102_10120_10189_10052_10053_10142_10107_10050_10051-10120,searchweb201603_5,ppcSwitch_5&btsid=4b333183-9955-44bb-a985-eb0a3aed0e3f&algo_expid=ad603dac-549a-4315-8ae9-50a2bd436e1b-17&algo_pvid=ad603dac-549a-4315-8ae9-50a2bd436e1b
or
https://www.aliexpress.com/item/50pcs-lot-Free-shipping-SMD-ceramic-gas-discharge-tube-BC401M-1812-400V-2KA-4-5X3-2X2/32428795826.html?spm=2114.search0104.3.119.qYG2gx&ws_ab_test=searchweb0_0,searchweb201602_5_10152_10065_10151_10068_10130_10084_10083_10119_10080_10082_10081_10110_10178_10136_10137_10111_10060_10112_5360018_10113_10155_10114_10154_438_10056_10055_10054_10182_10059_100031_10099_10078_10079_10103_10073_10102_10120_10189_10052_10053_10142_10107_10050_10051-10120,searchweb201603_5,ppcSwitch_5&btsid=4b333183-9955-44bb-a985-eb0a3aed0e3f&algo_expid=ad603dac-549a-4315-8ae9-50a2bd436e1b-16&algo_pvid=ad603dac-549a-4315-8ae9-50a2bd436e1b

[NeverDie]

@Nca78 said in Office plant monitor:

@NeverDie they are all very small inside (5-6mm) so are only suitable for very thin PCB with SMD version of the sensor, even the breakout of si7021 that you linked is too big.

I haven't confirmed it, but FWIW according to: http://www.wxforum.net/index.php?topic=32182.0
"The model shown in this link is too small for I2C boards, but seller has much larger models. L-04 has 12.8mm opening, L-06 has 17 mm and L-10 has 23mm opening."

[NeverDie]

@NeverDie
I've since had some communication with the seller. He said, "We have these dimensions," in reference to the photo below that he had attached:

[NeverDie]

The seller says I can buy 3 of the 1" diameter units at $5/pc.

The communication with the seller is like playing 20 questions, but I only get to ask one question at a time, with typically one day turnaround for an answer. If I ask more than one question per interaction, he doesn't really answer any of them. So, getting truly meaningful answers is a slow process.

[Nca78]

@NeverDie that sounds expensive, and I'm worried that at this size it's going to be difficult to stick in the soil for small plants...

[NeverDie]

@Nca78
Well, for small potted plants, you might have to re-pot the plant. However, the nice benefit that would arise is: no visible sensors, which carries with it very high WAF.

[aramko aramko]

This post is deleted!