Slim Node Si7021 sensor example

wergeld

After soldering the 3 pads on the HTU21D I am now reading data and it is being sent to my test serial gateway. Need to measure current usage but at least it is functional.

wergeld

Okay, seeing something odd. The force transmit does not appear to be working.
Here is my current sketch:

#define MY_RADIO_NRF24

#include <MyConfig.h>
#include <MySensors.h>

/* Sketch with Si7021 and battery monitoring.
by m26872, 20151109 
*/
//#include <MySensors.h>  
#include <Wire.h>
#include <SparkFunHTU21D.h>
#include <SPI.h>
#include <RunningAverage.h>

//#define DEBUG

#ifdef DEBUG
#define DEBUG_SERIAL(x) Serial.begin(x)
#define DEBUG_PRINT(x) Serial.print(x)
#define DEBUG_PRINTLN(x) Serial.println(x)
#else
#define DEBUG_SERIAL(x)
#define DEBUG_PRINT(x) 
#define DEBUG_PRINTLN(x) 
#endif

#define NODE_ID 132             // <<<<<<<<<<<<<<<<<<<<<<<<<<<   Enter Node_ID
#define CHILD_ID_TEMP 0
#define CHILD_ID_HUM 1
// #define SLEEP_TIME 15000 // 15s for DEBUG
#define SLEEP_TIME 300000   // 5 min
#define FORCE_TRANSMIT_CYCLE 36  // 5min*12=1/hour, 5min*36=1/3hour 
#define BATTERY_REPORT_CYCLE 2880   // Once per 5min   =>   12*24*7 = 2016 (one report/week)
#define VMIN 1900
#define VMAX 3300
#define HUMI_TRANSMIT_THRESHOLD 3.0  // THRESHOLD tells how much the value should have changed since last time it was transmitted.
#define TEMP_TRANSMIT_THRESHOLD 0.5
#define AVERAGES 2

int batteryReportCounter = BATTERY_REPORT_CYCLE - 1;  // to make it report the first time.
int measureCount = 0;
float lastTemperature = -100;
int lastHumidity = -100;

RunningAverage raHum(AVERAGES);
HTU21D humiditySensor;

//MySensor gw;
MyMessage msgTemp(CHILD_ID_TEMP,V_TEMP); // Initialize temperature message
MyMessage msgHum(CHILD_ID_HUM,V_HUM);

void presentation()  
{ 
  sendSketchInfo("HTU21D", "1.0"); 
  present(CHILD_ID_TEMP, S_TEMP);   // Present sensor to controller
  present(CHILD_ID_HUM, S_HUM);
}

void setup() {
  DEBUG_SERIAL(9600);    // <<<<<<<<<<<<<<<<<<<<<<<<<< Note BAUD_RATE in MySensors.h
  DEBUG_PRINTLN("Serial started");
  
  DEBUG_PRINT("Voltage: ");
  DEBUG_PRINT(readVcc()); 
  DEBUG_PRINTLN(" mV");
/*
  delay(500);
  DEBUG_PRINT("Internal temp: ");
  DEBUG_PRINT(GetInternalTemp()); // Probably not calibrated. Just to print something.
  DEBUG_PRINTLN(" *C");
*/  
  delay(500); // Allow time for radio if power useed as reset
  //gw.begin(NULL,NODE_ID);
  //sendSketchInfo("HTU21D", "1.0"); 
  //present(CHILD_ID_TEMP, S_TEMP);   // Present sensor to controller
  //present(CHILD_ID_HUM, S_HUM);
  DEBUG_PRINT("Node and "); DEBUG_PRINTLN("2 children presented.");
  
  raHum.clear();
  
}

void loop() { 

  measureCount ++;
  batteryReportCounter ++;
  bool forceTransmit = false;
  
  if (measureCount > FORCE_TRANSMIT_CYCLE) {
    forceTransmit = true; 
  }
  sendTempHumidityMeasurements(forceTransmit);
/*
  // Read and print internal temp
  float temperature0 = static_cast<float>(static_cast<int>((GetInternalTemp()+0.5) * 10.)) / 10.;
  DEBUG_PRINT("Internal Temp: "); DEBUG_PRINT(temperature0); DEBUG_PRINTLN(" *C");        
*/
  // Check battery
  if (batteryReportCounter >= BATTERY_REPORT_CYCLE) {
    long batteryVolt = readVcc();
    DEBUG_PRINT("Battery voltage: "); DEBUG_PRINT(batteryVolt); DEBUG_PRINTLN(" mV");
    uint8_t batteryPcnt = constrain(map(batteryVolt,VMIN,VMAX,0,100),0,255);   
    DEBUG_PRINT("Battery percent: "); DEBUG_PRINT(batteryPcnt); DEBUG_PRINTLN(" %");
    sendBatteryLevel(batteryPcnt);
    batteryReportCounter = 0;
  }
  
  sleep(SLEEP_TIME);
}

// function for reading Vcc by reading 1.1V reference against AVcc. Based from http://provideyourown.com/2012/secret-arduino-voltmeter-measure-battery-voltage/
// To calibrate reading replace 1125300L with scale_constant = internal1.1Ref * 1023 * 1000, where internal1.1Ref = 1.1 * Vcc1 (per voltmeter) / Vcc2 (per readVcc() function) 
long readVcc() {
  // set the reference to Vcc and the measurement to the internal 1.1V reference
  ADMUX = _BV(REFS0) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
  delay(2); // Wait for Vref to settle
  ADCSRA |= _BV(ADSC); // Start conversion
  while (bit_is_set(ADCSRA,ADSC)); // measuring
  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
}
// function for reading internal temp. From http://playground.arduino.cc/Main/InternalTemperatureSensor 
double GetInternalTemp(void) {  // (Both double and float are 4 byte in most arduino implementation)
  unsigned int wADC;
  double t;
  // The internal temperature has to be used with the internal reference of 1.1V. Channel 8 can not be selected with the analogRead function yet.
  ADMUX = (_BV(REFS1) | _BV(REFS0) | _BV(MUX3));   // Set the internal reference and mux.
  ADCSRA |= _BV(ADEN);  // enable the ADC
  delay(20);            // wait for voltages to become stable.
  ADCSRA |= _BV(ADSC);  // Start the ADC
  while (bit_is_set(ADCSRA,ADSC));   // Detect end-of-conversion
  wADC = ADCW;   // Reading register "ADCW" takes care of how to read ADCL and ADCH.
  t = (wADC - 88.0 ) / 1.0;   // The default offset is 324.31.
  return (t);   // The returned temperature in degrees Celcius.
}

/*********************************************
 * * Sends temperature and humidity from Si7021 sensor
 * Parameters
 * - force : Forces transmission of a value (even if it's the same as previous measurement)
 *********************************************/
void sendTempHumidityMeasurements(bool force) {
  bool tx = force;
  
  float temperature = humiditySensor.readTemperature();
  DEBUG_PRINT("T: ");DEBUG_PRINTLN(temperature);

  float diffTemp = abs(lastTemperature - temperature);
  DEBUG_PRINT(F("TempDiff :"));DEBUG_PRINTLN(diffTemp);

  if (diffTemp > TEMP_TRANSMIT_THRESHOLD || tx) {
    send(msgTemp.set(temperature,1));
    lastTemperature = temperature;
    measureCount = 0;
    DEBUG_PRINTLN("T sent!");
  }
  
  int humidity = humiditySensor.readHumidity();
  DEBUG_PRINT("H: ");DEBUG_PRINTLN(humidity);

  raHum.addValue(humidity);
  humidity = raHum.getAverage();  // MA sample imply reasonable fast sample frequency
  float diffHum = abs(lastHumidity - humidity);
  DEBUG_PRINT(F("HumDiff  :"));DEBUG_PRINTLN(diffHum); 

  if (diffHum > HUMI_TRANSMIT_THRESHOLD || tx) {
    send(msgHum.set(humidity));
    lastHumidity = humidity;
    measureCount = 0;
    DEBUG_PRINTLN("H sent!");
  }
}

I am at 1+ hours since last transmission.

m26872

@wergeld It looks like it's set to 3 hrs.

wergeld

@m26872
Indeed it does. Just was throwing me off with the wording. I read it as "1/2 hour" or "1/3 hour". So far I am prepping up more nodes. Have 4 more 328s to programs and build out. I am thinking at the end I will have:

Gateway (serial or the direct connect nrf+ once it supports v2)
Temp/Hum node using HTU21D for back porch sending every 5 minutes and force send every 30 minutes.
Temp/Hum node using HTU21D inside using same send times.
Parking sensor in garage hardwired to mains.
5 & 6 I am not sure yet.

Lots of fun so far.

wergeld

I am seeing 5.0 μA at sleep and 12.4 mA when transmitting. Seems kind of high. I did the poor man's test as well - put an LED across the HTU21D power pins and it lit up. Same when I did it across the nrf's power pins. Shouldn't the MySensors code turn off the power rails during sleep?

GertSanders

@wergeld

No, the powerrails are not turned off, just the devices themselves.

5uA during sleep is about right. The 12.4mA during transmit is also normal, but the transmit time should be very short, so on average the total consumption of power will be low.

wergeld

@GertSanders Excellent! I was hoping I hadn't wired it up wrong. So far the 2 nodes have been flawless for the past 3 days. Next step is to await the direct attached NRF serial gateway to be v2 compatible. Been following along with this thread. Looks like we are getting closer! I have 2 RPis (one a first gen B and the other a Pi2 B ) with this adapter by ceech:
https://www.openhardware.io/view/100/Raspberry-PI-NRF24l01-hat

clempat

Hi everyone,

First thanks for sharing. I love this slim node. But I am facing some issues I did not success to debug. So I use the code shared here for mysensors 2. I try with the mysensors exemple library (did not work at all). I try with the https://github.com/LowPowerLab/SI7021 which worked (at least for getting separately temperature and humidity and using the example file) on an arduino nano. But when I run this sensor with the slim node (red, boot loader 8mhz) and the code (for 2.0.0) I always get -46.85 for temperature and 118 for humidity. Otherwise the radio work normally.

Winter is coming and I don't know what I could do anymore. Thanks to share you idea on this.

With the example code I use on the nano. I get with the slim node:

T: -46.85
H: 118
device ID: 50

With Arduino nano:

T: 24.34
H: 43
device ID: 50

clempat

Why actually my device id is 50 ? for what 50 stands !?!?!

m26872

@clempat Please post your sketch and maybe some hardware photo or diagram too.

clempat

@m26872 Sure I can do that. So I simplified the code to only focus on the si7021.

Here it is: https://github.com/clempat/example-si7021

And there the photo:

m26872

@clempat Don't think I can help you. Maybe clock related. What voltages do you use on Nano and Slim respectively? Do you have multiple parts to try with and get the same result? Why do you include and start wire.h, isn't already in Si7021.h ? My guess on "device Id 50" is that it's just a chinese clone reply.
Photos look nice btw. :thumbsup:

clempat

@m26872 Thank you. Yes I wanted to try with a pro mini 8Mhz but I need to prepare the pin 4 and 5. I will keep inform when I do it this week end.

Thanks for the picture but with this nice setup it is difficult to make it bad :)...

I includes wire.h like in the exemple in https://github.com/LowPowerLab/SI7021 but of course after I tried without. The nano was directly connected to usb and the slim through 3,3V USB to serial.

clempat

Ok with the arduino micro 8Mhz all works good too.

Reading...
T: 20.29
H: 54
device ID: 50

clempat

So sad I still not getting it working with the slim node :( !!! Always same result either with internal 1mhz or 8mhz...

m26872

@clempat Make it with external 8MHz then ? Then it should be like a Pro Mini 3.3V.

clempat

@m26872 I will give a try and let you know... Thanks.

miljume

Hello

I also have big problems with getting the node to send temp and hum values
It starts up and presents itself to the GW but then nothing happens

I have tested the SI721 module with a simple arduino code and then it reads and prints both values just fine

My code is below, in practice its a version of Sensebender Micro code. I have changed the force transmit value to 1
Exactly as @clempat I have tried both 1MHz optiboot and 8MHz internal oscillator without any success

/**
* 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.
*
*******************************
*
* REVISION HISTORY
* Version 1.0 - Thomas Bowman MC8rch
*
* DESCRIPTION
* Default sensor sketch for Sensebender Micro module
* Act as a temperature / humidity sensor by default.
*
* If A0 is held low while powering on, it will enter testmode, which verifies all on-board peripherals
*
* Battery voltage is as battery percentage (Internal message), and optionally as a sensor value (See defines below)
*
*
* Version 1.3 - Thomas Bowman MC8rch
* Improved transmission logic, eliminating spurious transmissions (when temperatuere / humidity fluctuates 1 up and down between measurements)
* Added OTA boot mode, need to hold A1 low while applying power. (uses slightly more power as it's waiting for bootloader messages)
*
* Version 1.4 - Thomas Bowman MC8rch
*
* Corrected division in the code deciding whether to transmit or not, that resulted in generating an integer. Now it's generating floats as expected.
* Simplified detection for OTA bootloader, now detecting if MY_OTA_FIRMWARE_FEATURE is defined. If this is defined sensebender automaticly waits 300mS after each transmission
* Moved Battery status messages, so they are transmitted together with normal sensor updates (but only every 60th minute)
*
*/

// Enable debug prints to serial monitor
#define MY_DEBUG 

// Define a static node address, remove if you want auto address assignment
//#deine MY_NODE_ID 3

// Enable and select radio type attached
#define MY_RADIO_NRF24
//#define MY_RADIO_RFM69

#include <SPI.h>
#include <MySensors.h>
#include <Wire.h>
#include <SI7021-master\SI7021.h>
#include <RunningAverage.h>


// Uncomment the line below, to transmit battery voltage as a normal sensor value
#define BATT_SENSOR    199

#define RELEASE "1.4"

#define AVERAGES 2

// Child sensor ID's
#define CHILD_ID_TEMP  1
#define CHILD_ID_HUM   2

// How many milli seconds between each measurement
#define MEASURE_INTERVAL 60000

// FORCE_TRANSMIT_INTERVAL, this number of times of wakeup, the sensor is forced to report all values to the controller
#define FORCE_TRANSMIT_INTERVAL 1 

// When MEASURE_INTERVAL is 60000 and FORCE_TRANSMIT_INTERVAL is 30, we force a transmission every 30 minutes.
// Between the forced transmissions a tranmission will only occur if the measured value differs from the previous measurement

// HUMI_TRANSMIT_THRESHOLD tells how much the humidity should have changed since last time it was transmitted. Likewise with
// TEMP_TRANSMIT_THRESHOLD for temperature threshold.
#define HUMI_TRANSMIT_THRESHOLD 0.5
#define TEMP_TRANSMIT_THRESHOLD 0.5

SI7021 humiditySensor;

// Sensor messages
MyMessage msgHum(CHILD_ID_HUM, V_HUM);
MyMessage msgTemp(CHILD_ID_TEMP, V_TEMP);

#ifdef BATT_SENSOR
MyMessage msgBatt(BATT_SENSOR, V_VOLTAGE);
#endif

// Global settings
int measureCount = 0;
int sendBattery = 0;
boolean isMetric = true;
boolean highfreq = true;
boolean transmission_occured = false;

// Storage of old measurements
float lastTemperature = -100;
int lastHumidity = -100;
long lastBattery = -100;

RunningAverage raHum(AVERAGES);

/****************************************************
*
* Setup code
*
****************************************************/
void setup() {

	Serial.begin(9600);
	Serial.print(F("Sensebender Micro FW "));
	Serial.print(RELEASE);
	Serial.flush();

	humiditySensor.begin();

	Serial.flush();
	Serial.println(F(" - Online!"));

	isMetric = getConfig().isMetric;
	Serial.print(F("isMetric: ")); Serial.println(isMetric);
	raHum.clear();
	sendTempHumidityMeasurements(false);
	sendBattLevel(false);


}

void presentation() {
	sendSketchInfo("TempHum", RELEASE);

	present(CHILD_ID_TEMP, S_TEMP);
	present(CHILD_ID_HUM, S_HUM);

#ifdef BATT_SENSOR
	present(BATT_SENSOR, S_POWER);
#endif
}


/***********************************************
*
*  Main loop function
*
***********************************************/
void loop() {

	measureCount++;
	sendBattery++;
	bool forceTransmit = false;
	transmission_occured = false;

	if (measureCount > FORCE_TRANSMIT_INTERVAL) { // force a transmission
		forceTransmit = true;
		measureCount = 0;
	}

	sendTempHumidityMeasurements(forceTransmit);
	/*  if (sendBattery > 60)
	{
	sendBattLevel(forceTransmit); // Not needed to send battery info that often
	sendBattery = 0;
	}*/

	sleep(MEASURE_INTERVAL);
}


/*********************************************
*
* Sends temperature and humidity from Si7021 sensor
*
* Parameters
* - force : Forces transmission of a value (even if it's the same as previous measurement)
*
*********************************************/
void sendTempHumidityMeasurements(bool force)
{
	bool tx = force;

	si7021_env data = humiditySensor.getHumidityAndTemperature();

	raHum.addValue(data.humidityPercent);

	float diffTemp = abs(lastTemperature - (isMetric ? data.celsiusHundredths : data.fahrenheitHundredths) / 100.0);
	float diffHum = abs(lastHumidity - raHum.getAverage());

	Serial.print(F("TempDiff :"));Serial.println(diffTemp);
	Serial.print(F("HumDiff  :"));Serial.println(diffHum);

	if (isnan(diffHum)) tx = true;
	if (diffTemp > TEMP_TRANSMIT_THRESHOLD) tx = true;
	if (diffHum > HUMI_TRANSMIT_THRESHOLD) tx = true;

	if (tx) {
		measureCount = 0;
		float temperature = (isMetric ? data.celsiusHundredths : data.fahrenheitHundredths) / 100.0;

		int humidity = data.humidityPercent;
		Serial.print("T: ");Serial.println(temperature);
		Serial.print("H: ");Serial.println(humidity);

		send(msgTemp.set(temperature, 1));
		send(msgHum.set(humidity));
		lastTemperature = temperature;
		lastHumidity = humidity;
		transmission_occured = true;
		if (sendBattery > 60) {
			sendBattLevel(true); // Not needed to send battery info that often
			sendBattery = 0;
		}
	}
}
/********************************************
*
* Sends battery information (battery percentage)
*
* Parameters
* - force : Forces transmission of a value
*
*******************************************/
void sendBattLevel(bool force)
{
	if (force) lastBattery = -1;
	long vcc = readVcc();
	if (vcc != lastBattery) {
		lastBattery = vcc;

#ifdef BATT_SENSOR
		float send_voltage = float(vcc) / 1000.0f;
		send(msgBatt.set(send_voltage, 3));
#endif

		// Calculate percentage

		vcc = vcc - 1900; // subtract 1.9V from vcc, as this is the lowest voltage we will operate at

		long percent = vcc / 14.0;
		sendBatteryLevel(percent);
		transmission_occured = true;
	}
}

/*******************************************
*
* Internal battery ADC measuring
*
*******************************************/
long readVcc() {
	// Read 1.1V reference against AVcc
	// set the reference to Vcc and the measurement to the internal 1.1V reference
#if defined(__AVR_ATmega32U4__) || defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
	ADMUX = _BV(REFS0) | _BV(MUX4) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
#elif defined (__AVR_ATtiny24__) || defined(__AVR_ATtiny44__) || defined(__AVR_ATtiny84__)
	ADMUX = _BV(MUX5) | _BV(MUX0);
#elif defined (__AVR_ATtiny25__) || defined(__AVR_ATtiny45__) || defined(__AVR_ATtiny85__)
	ADcdMUX = _BV(MUX3) | _BV(MUX2);
#else
	ADMUX = _BV(REFS0) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
#endif  

	delay(2); // Wait for Vref to settle
	ADCSRA |= _BV(ADSC); // Start conversion
	while (bit_is_set(ADCSRA, ADSC)); // measuring

	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

}

m26872

It would be interesting if someone with issues also tried older versions of libs for Si7021 and/or MySensors.

wergeld

So, after a few months of 2 nodes up and running using the HTU21D sensor I have come the conclusion that the HTU21D is no good for where I live. Lately it has been getting cooler outside (down to mid 50s F) but humidity is still high. As the evening progresses the humidity gets to 100% and the node no longer sends data. This happens around 6pm every day (about half and hour after sunset). It then comes back online at about 10 am the next day. The node that I have inside does not have this issue (same shipment of arduino, pcb, and HTU21D sensors and the same arduino code). Both running off of fresh AAs. May need to upgrade to the SI7021 for outside node.

Here is the graph showing last 7 days. As you can see it flatlines (literally!) at 100% humidity!

All good times with the learning!

Slim Node Si7021 sensor example

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