Slim Node Si7021 sensor example



  • @ar91 Please find the code I used in 3 different nodes. The good thing with the playground lib is that there is error message if dialog with DHT22 failed.

    /**
     * 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.
     *
     */
    
    /**************************************************************************************/
    /* Temperature, humidity and luminosity measurements.                                 */
    /*                                                                                    */
    /* Version     : 1.1.6                                                                */
    /* Date        : 10/01/2016                                                           */
    /* Modified by : David Carlier                                                        */
    /**************************************************************************************/
    /*                                ---------------                                     */
    /*                            RST |             |  A5                                 */
    /*                            RX  |             |  A4                                 */
    /*                            TX  |   ARDUINO   |  A3                                 */
    /*     RFM69 (DIO0) --------- D2  |     UNO     |  A2                                 */
    /*            DHT22 --------- D3  |             |  A1                                 */
    /*            Power --------- D4  | ATMEGA 328p |  A0 --------- Light dep. resistor   */
    /*              +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)           */
    /*                            D8  |             |  D9                                 */
    /*                                ---------------                                     */
    /*                                                                                    */
    /* Power = Vcc for LDR.                                                               */
    /* +3v = 2*AA                                                                         */
    /*                                                                                    */
    /**************************************************************************************/
    
    #include <SPI.h>
    #include <MySensor.h>
    #include <dht.h>
    #include <MyTransportRFM69.h>
    #include <MySigningAtsha204Soft.h>
    
    #define CHILD_ID_HUM 0
    #define CHILD_ID_TEMP 1
    #define CHILD_ID_LIGHT 2
    #define CHILD_ID_VOLTAGE 3
    #define LIGHT_SENSOR_ANALOG_PIN 0
    #define HUMIDITY_SENSOR_DIGITAL_PIN 3
    #define POWER_PIN 4
    //unsigned long SLEEP_TIME = 850000; // Sleep time between reads (in milliseconds) (close to 15')
    unsigned long SLEEP_TIME = 275000; // Sleep time between reads (in milliseconds) (close to 5')
    
    //Construct MySensors library
    MySigningAtsha204Soft signer;
    MyHwATMega328 hw;
    MyTransportRFM69 transport;
    MySensor gw(transport, hw, signer);
    dht DHT;
    MyMessage msgHum(CHILD_ID_HUM, V_HUM);
    MyMessage msgTemp(CHILD_ID_TEMP, V_TEMP);
    MyMessage msgLum(CHILD_ID_LIGHT, V_LEVEL);
    MyMessage msgVolt(CHILD_ID_VOLTAGE, V_VOLTAGE);
    
    /**************************************************************************************/
    /* Initialization                                                                     */
    /**************************************************************************************/
    void setup()
      {
      //Get time (for setup duration)
      #ifdef DEBUG
        unsigned long startTime = millis();
      #endif
    
      //Start MySensors
      gw.begin();
    
      //Send the Sketch Version Information to the Gateway
      gw.sendSketchInfo("GHAS sensor", "1.1.5");
    
      //Register all sensors to gw (they will be created as child devices)
      gw.present(CHILD_ID_HUM, S_HUM);
      gw.present(CHILD_ID_TEMP, S_TEMP);
      gw.present(CHILD_ID_LIGHT, S_LIGHT_LEVEL);
      gw.present(CHILD_ID_VOLTAGE, S_MULTIMETER);
    
      //Delay for DHT22
      delay(1500);
    
      //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
    
      //Power on
      powerOnPeripherals();
    
      //Get DHT22 data
      int dht22Result = DHT.read22(HUMIDITY_SENSOR_DIGITAL_PIN);
      switch (dht22Result)
        {
        case DHTLIB_OK:  
                    //Serial.println("OK,\t");
                    break;
        case DHTLIB_ERROR_CHECKSUM:
                    #ifdef DEBUG
                      Serial.println("Checksum error,\t");
                    #endif
                    break;
        case DHTLIB_ERROR_TIMEOUT:
                    #ifdef DEBUG
                      Serial.println("Time out error,\t");
                    #endif
                    break;
        case DHTLIB_ERROR_CONNECT:
                    #ifdef DEBUG
                      Serial.println("Connect error,\t");
                    #endif
                    break;
        case DHTLIB_ERROR_ACK_L:
                    #ifdef DEBUG
                      Serial.println("Ack Low error,\t");
                    #endif
                    break;
        case DHTLIB_ERROR_ACK_H:
                    #ifdef DEBUG
                      Serial.println("Ack High error,\t");
                    #endif
                    break;
        default:
                    #ifdef DEBUG
                      Serial.println("Unknown error,\t");
                    #endif
                    break;
        }
    
      //Get temperature and humidity
      float temperature = 0;
      float humidity = 0;
      if (dht22Result == DHTLIB_OK)
        {
        temperature = DHT.temperature;
        humidity = DHT.humidity;
        }
    
      //Get power before luminosity to use real voltage
      float realVoltage = getVoltage() / 100.0;
      int batteryPcnt = realVoltage * 100 / 3.0;
      if (batteryPcnt > 100) {batteryPcnt = 100;}
      int lux = computeIlluminance(realVoltage);
    
      //Power off
      powerOffPeripherals();
    
      //Send data to gateway
      gw.send(msgHum.set(humidity, 1));
      gw.send(msgTemp.set(temperature, 1));
      gw.send(msgLum.set(lux));
      gw.send(msgVolt.set(realVoltage, 2));
      gw.sendBatteryLevel(batteryPcnt);
    
      //Print debug
      #ifdef DEBUG
        Serial.print(temperature, 1);
        Serial.print(" degC");
        Serial.print("   ");
        Serial.print(humidity, 1);
        Serial.print(" %");
        Serial.print("   ");
        Serial.print(lux);
        Serial.print(" lx");
        Serial.print("   ");
        Serial.print(realVoltage);
        Serial.print(" v");
        int duration = millis() - startTime;
        Serial.print("   ");
        Serial.print("["); Serial.print(duration, DEC); Serial.println(" ms]");
        Serial.flush();
      #endif
    
      //Sleep
      gw.sleep(SLEEP_TIME);
      }
    
    /**************************************************************************************/
    /* Allows to compute illuminance (in LUX) from LIGHT_SENSOR_ANALOG_PIN.               */
    /**************************************************************************************/
    int computeIlluminance(float realVoltage)
      {
      //Get luminosity
      int luminosity = analogRead(LIGHT_SENSOR_ANALOG_PIN);
      //Calculating the voltage in the input of the ADC
      double voltage = realVoltage * ((double)luminosity / 1024.0);
      //Calculating the resistance of the photoresistor in the voltage divider
      double resistance = (10.0 * realVoltage) / voltage - 10.0;
      //Calculating the intensity of light in lux and return it
      int illuminance = 255.84 * pow(resistance, -10/9);
      return illuminance;
      }
    
    /**************************************************************************************/
    /* Allows to get the real Vcc (return value * 100).                                   */
    /**************************************************************************************/
    int getVoltage()
      {
      const long InternalReferenceVoltage = 1056L;
      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 (((ADCSRA & (1<<ADSC)) != 0));
      //Scale the value
      int result = (((InternalReferenceVoltage * 1023L) / ADC) + 5L) / 10L;
      return result;
      }
    
    /**************************************************************************************/
    /* Allows to power ON peripherals.                                                    */
    /**************************************************************************************/
    void powerOnPeripherals()
      {
      //Power-up
      pinMode (POWER_PIN, OUTPUT);
      digitalWrite (POWER_PIN, HIGH);
      delay(1);
      }
    
    /**************************************************************************************/
    /* Allows to power OFF peripherals.                                                   */
    /**************************************************************************************/
    void powerOffPeripherals()
      {
      //Power off
      digitalWrite (HUMIDITY_SENSOR_DIGITAL_PIN, LOW);
      digitalWrite (POWER_PIN, LOW);
      pinMode (HUMIDITY_SENSOR_DIGITAL_PIN, INPUT);
      pinMode (POWER_PIN, INPUT);
      }
    

    Hope it helps !

    David.



  • @carlierd Thank you very much. I really like your comment on the top 👍



  • Progress!

    http://imgur.com/zRvXvrN
    http://imgur.com/KpB7daz

    A question though. To get to this point, I copied the pictures posted above, but where do I now add these resistors?

    http://imgur.com/6mKJcgE

    Also, if I want to add a 2AA battery cage, where do I connect the red and black wires to?

    Thanks! And sorry for the newb questions!


  • Hardware Contributor

    @rsachoc What you show are not resistors, they look like capacitors. 104 means 100nF (I think). Can you measure their value ?



  • @carlierd Are you running your Atmega at 1Mhz, Because I tried to use your sketch and i am getting "Checksum Error".



  • @GertSanders indeed they are capacitors (silly me) - apparently they are 0.1uf - the black one I have already soldered is 4.7uf



  • @ar91 said:

    @carlierd Are you running your Atmega at 1Mhz, Because I tried to use your sketch and i am getting "Checksum Error".

    No, I am working at 8 MHz (internal). Perhaps your DHT is out of order ? You try with another one ?

    David.



  • Bump, can anyone advise on how I got about finding out where I need to solder the resistors on? So far I've just soldered the 4.7uf capacitor, as can be seen from the pics. But I'm struggling to find out where I need to solder the other capacitor's I have (from the BOM).


  • Hardware Contributor

    @rsachoc C1,C2,C3 are clearly marked at top layer silkscreen. You'll see them in the middle of the uC socket if you look at your 2nd picture in you last post above. C5 is visible next to the 4.7u cap, in the 3rd picture of my first post in this thread.


  • Hardware Contributor

    @rsachoc said:

    Also, if I want to add a 2AA battery cage, where do I connect the red and black wires to?

    First picture in first post of this thread should be enough. Connect (+) to Vcc and (-) to Gnd.



  • Thanks, apologies, I really should have looked at my board, I was searching for the answer in the main slim node thread and I think i was looking at older boards and couldn't for the life of me find where C3 is!


  • Hardware Contributor

    @rsachoc I'm sorry, I know I need to update those old pictures.



  • @m26872 no problem, not your fault at all, mine for being a newbie. So much so that my first attempt resulted in me soldering the capacitor to the wrong hole, so I've had to abandon my first attempt. You live, you learn, next time I'll double check.


  • Hardware Contributor

    @rsachoc Yes. Double check polarity of the 4.7uF cap.



  • Hi all, again.

    I have now successfully built (I think) the slim node, but without the 7021 temp sensor. Because this is the most expensive part of the device and because I find desoldering a challenge, but mainly because I'm waiting for it to arrive from China, can I try and upload the bootloader and sketch without the sensor attached?

    If so, I had a couple questions from reading through this thread and the slim node thread. Firstly, uploading the bootloader, can this be done with the FTDI adaptor or do I need to follow the bit described in the slim node thread and attempt it using AVR studio? Secondly, once that is done, is it just a matter of uploading the sketch provided above?

    Also, I wanted to confirm a few things on attaching the si7021 temp sensor. From what I can see, SOA (SDA) on the si7021 goes to A4 and SCL goes to A5. Also, GND goes to GND on the board (rightmost set on pins bottom right when FTDI is at the top) and VIN goes to VCC (just next to GND on the board)?

    Thanks in advance.


  • Hardware Contributor

    @rsachoc said:

    can I try and upload the bootloader and sketch without the sensor attached?

    Yes, you should be able to get far without the sensor. Send something over MySensors net and view debug prints. Or make some simple sensor like a reed switch.

    uploading the bootloader, can this be done with the FTDI adaptor or do I need to follow the bit described in the slim node thread and attempt it using AVR studio?

    Yes, Avr Studio or Uno as ISP.

    Secondly, once that is done, is it just a matter of uploading the sketch provided above?

    Yes, but if you don't connect a Si7021 I would go for some other simple test sketch to avoid any Si7021 library startup issues.

    Also, I wanted to confirm a few things on attaching the si7021 temp sensor. From what I can see, SOA (SDA) on the si7021 goes to A4 and SCL goes to A5. Also, GND goes to GND on the board (rightmost set on pins bottom right when FTDI is at the top) and VIN goes to VCC (just next to GND on the board)?

    Yes.



  • Folks, a word of caution, for people that are attempting this for the first time, please burn the bootloader before you solder everything, as silly me, I built the entire thing (without the si7021) and now I'll need to bin it because the ATMega is soldered to the board and I've no way to load the bootloader soldered to the board!

    Ah, the life of a newbie 😁

    I think what I'll do is once I've actually got a working board, I'll do a newbie writeup so that people don't make the same mistakes as me.


  • Mod

    First Attempt In Learning 🙂 A writeup would be awesome.


  • Hardware Contributor

    @rsachoc Why don't you just solder some wires to pins you need ? The "in cicuit serial programming" concept would let you do it with almost anything attached.



  • @m26872 said:

    @rsachoc Why don't you just solder some wires to pins you need ? The "in cicuit serial programming" concept would let you do it with almost anything attached.

    I might as well attempt that! I'm waiting for a breadboard, so I'll try and attempt it when that arrives.


 

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