Slim Node Si7021 sensor example

rsachoc

I just received my non-3.3v Si7021, and have now updated the lessons learnt post, as this board is tiny and I managed to mess up the soldering completely. Ordered the 3.3 ready version now, another month wait...

siod

@carlierd said:

@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.

So the DHT22 works at 1MHz with 2 AAs and your code you´ve posted? No physical differnces?

rsachoc

So I think I've finally got everything up and running! This is what I'm getting at the serial monitor in the IDE:

Serial started
Voltage: 3359 mV
send: 132-132-0-0 s=255,c=3,t=15,pt=2,l=2,sg=0,st=ok:0
send: 132-132-0-0 s=255,c=0,t=17,pt=0,l=5,sg=0,st=ok:1.5.4
send: 132-132-0-0 s=255,c=3,t=6,pt=1,l=1,sg=0,st=ok:0
read: 0-0-132 s=255,c=3,t=15,pt=0,l=2,sg=0:
sensor started, id=132, parent=0, distance=1
send: 132-132-0-0 s=255,c=3,t=11,pt=0,l=15,sg=0,st=ok:EgTmpHumBat5min
send: 132-132-0-0 s=255,c=3,t=12,pt=0,l=10,sg=0,st=ok:1.0 151106
send: 132-132-0-0 s=0,c=0,t=6,pt=0,l=0,sg=0,st=ok:
send: 132-132-0-0 s=1,c=0,t=7,pt=0,l=0,sg=0,st=ok:
Node and 2 children presented.

What I'm trying to figure out is where the temp and humidity reading are so I can get them into MQTT/OpenHab. Looking at the output, I can't see which one is the temp, humidity or battery level?

m26872

@rsachoc Is that all you get? Please also set sleep_time to 15000 for debug, if you haven't already done it.

rsachoc

@m26872 thanks, I've set that, no change even after more than 15seconds and debug set.

Could it be the way I've connected the si7021? I've got it as follows:

A4 to SDA
A5 to SCL
GND to GND
VCC to 3.3v

rsachoc

Maybe I need to add that I'm running the 2.0 MQTT controller? Not sure if that makes a difference? GatewayW5100MQTTClient

Just had a look what's going on on the controller side, this is what I see

0;255;3;0;9;Starting gateway (RNNGA-, 2.0.0-beta)
0;255;3;0;9;Radio init successful.
0;255;3;0;9;Init complete, id=0, parent=0, distance=0
0;255;3;0;9;Attempting MQTT connection...
0;255;3;0;9;MQTT connected
0;255;3;0;9;read: 132-132-0 s=255,c=3,t=15,pt=2,l=2,sg=0:0
0;255;3;0;9;send: 0-0-132-132 s=255,c=3,t=15,pt=0,l=2,sg=0,st=ok:
0;255;3;0;9;read: 132-132-0 s=255,c=0,t=17,pt=0,l=5,sg=0:1.5.4
0;255;3;0;9;Sending message on topic: mygateway1-out/132/255/0/0/17
0;255;3;0;9;read: 132-132-0 s=255,c=3,t=6,pt=1,l=1,sg=0:0
0;255;3;0;9;Sending message on topic: mygateway1-out/132/255/3/0/6
0;255;3;0;9;read: 132-132-0 s=255,c=3,t=11,pt=0,l=15,sg=0:EgTmpHumBat5min
0;255;3;0;9;Sending message on topic: mygateway1-out/132/255/3/0/11
0;255;3;0;9;read: 132-132-0 s=255,c=3,t=12,pt=0,l=10,sg=0:1.0 151106
0;255;3;0;9;Sending message on topic: mygateway1-out/132/255/3/0/12
0;255;3;0;9;read: 132-132-0 s=0,c=0,t=6,pt=0,l=0,sg=0:
0;255;3;0;9;Sending message on topic: mygateway1-out/132/0/0/0/6
0;255;3;0;9;read: 132-132-0 s=1,c=0,t=7,pt=0,l=0,sg=0:
0;255;3;0;9;Sending message on topic: mygateway1-out/132/1/0/0/7

m26872

@rsachoc
My initial guess would be that you get stuck at this line:

 si7021_env data = humiditySensor.getHumidityAndTemperature();

Did you try your Si7021 on some plain arduino first? Just with some simple example code.

rsachoc

@m26872 thanks, yes, I guessed that something might be wrong with the sensor, I checked continuity between the board and the sensor and all seemed fine.

To test on an Arduino, I've honestly very little clue how to do this. Could I utilise the breadboard and Arduino I used to flash the AtMega?

m26872

@rsachoc The "very little clue" is a good reason to play around and learn some. :smiley:
You should not use a 5V Uno directly to sensor without voltage regulator and logic level converter. The Si7021 spec is 1.9-3.6V.
If you don't have a Arduino Pro Mini 3.3V, I suppose your best option is the SlimNode you already got. Try it at least at 8MHz (use suitable fuse settings, bootloader and baud rate), of course external crystal if you have.

rollercontainer

The most SI7021 coming from ebay are with voltage regulator and level shifter. I searched for a raw version and there are only very few... If you are not sure, post a link or a foto.

m26872

@rollercontainer Thanks! You're absolutely right. I feel rather stupid not thinking of this. :(

So @rsachoc, if you're have some GY-21 like boards still not yet modded like described in first post of this thread, then they should work excellent with your Uno.

rsachoc

Thanks both, I have the "pre-modded" si7021, so it's the one that should operate at between the 1.9 and 3.3v. I the Arduino I used to burn the Atmega is a knockoff, so it has both 3.3v and 5v. Let me do some research and see if I can test the si7021 using it.

rsachoc

Some pictures anyway!

alt text

m26872

@rsachoc Great with pictures! It looks like you haven't enabled the pull-up resistors by filling the solder jumpers in the middle of the board? Like this: https://cdn.sparkfun.com/assets/3/f/6/5/a/52855764757b7f06478b4567.jpg

rsachoc

@m26872 oh! I didn't realise I needed to do that, could that be the problem? Do I just need to fill with solder the bit just below where the DA and "-" is?

m26872

@rsachoc It's probably it. And yes, it's rigth there. Make sure all of the three small pads interconnect.

rsachoc

@m26872 thanks! No time tonight, but a job for testing tomorrow.

DavidZH

You could also use the 328 pullups! I had an unwilling Chinese light sensor (MAX44099) that drew a lot of power either with the VCC on or off. Since it's battery powered that is undesireable.

I used digitalWrite(SDA, LOW); digitalWrite(SCL, LOW); to tie the bus to ground. When the sensor wakes up, it writes HIGH to those pins and the bus is back online. Used a 500ms wait after this to let the sensors stabilise.

That sensor is now on a 6µA sleep current and a average 128µA over 2 hours measured with a 2 minute sleep cycle.

rsachoc

Tried it this evening, still no luck, let me see what I can get up to over the weekend.

m26872

@DavidZH True, internal pull-ups (20k?) should probably be enough for the normal i2c use (short wires, low speed, etc). But I wonder if pull-ups are consuming any significant power during passive state like sleeping sensor. Of course it's a good solution in case there're issues preventing the bus from beeing silent. Or worse, pulled down continuously.
What was your current before the change?
I think 500ms awake is a lot.

Slim Node Si7021 sensor example

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