Small wall outlet sensor node

[olaeke]

@axillent Very nice! How do you make the circuit board and the soldering of surface mounted components is quit advanced.

[axillent]

@gregl thanks, yes, the same board can be used for any simple 1-2 inputs or 1-2 channel actuator

I have a plan to create something similar for wall switch in 3-wire and 2-wire versions

[axillent]

@hek thanks
I read a datasheet and I doubt about where to use it
it requires quite a big external filter
the total size will be bigger than normal isolated AC-DC

The supply based on none-isoleted schema is interested in some projects where you need lower footprint.

If someone interested I will do a test

[axillent]

Here are a schematic and PCB prints

MySensors.Sens.atmega328-wall.PDF

[axillent]

@olaeke thanks!
it is half-a-day project including a home-production of the PCB
but it is a 2-year experience

I also use a simplified approach for some PCBs, without drilling, using 0.5mm FR4 cut by office scissors and thermo-transfer technology. This one requires about 30-50 minutes for the production circle.depending on etching speed. For example this two side AC lamp off-timer:
http://radiokot.ru/circuit/digital/automat/81/04.jpg
http://radiokot.ru/circuit/digital/automat/81/05.jpg

[axillent]

Pictures bellow are virtual, under printing

[gadu]

It would be cool with a 90degree angled version as well :)

[Heinz]

Excellent!

[RJ_Make]

@axillent Your an evil genius! :-)

[axillent]

@ServiceXp thanks)
all this is simple, just a patient work

Printed thing is a bit ugly comparing to the virtual one, but it's work is real

http://www.youtube.com/watch?v=JG7gutD1oo8

[gregl]

@axillent So very very cool!!

as @gadu commented, making one at 90 deg so its very low profile would be even better for places such as hallways where the sensor could be bumped....

Really nice!

[blacey]

@axillent - well done! :+1:

[bjornhallberg]

@axillent Very impressive! What is the total cost of the components involved?

[axillent]

@bjornhallberg it is hard to say
the BOM is simple and short
but the cost of a single component is dramatically depends on how many your purchase in a single order
for example atmega328 purchased in 10pcs will be US1.2 pcs while a single pcs will costs US3-4

If it will be an interest I think in production this PCB can cost retail US8-12

[gigi]

@axillent
very very cool!!

[nutcracker]

Impressive!

[axillent]

made two more with modified box - it is a bit wider to hold DHT sensor inside
I made a new sketch as a combination of Dalas example and DHT. This new sketch able to detect automatically connected sensors and work according to detection.

One problem I've got. I cannot get DHT working from AC plug. It is working fine been powered from DC and failed during startup been powered from AC :( The most probably the reason is high pulsation (up to 440mV) coming from the supply based on SR10 chip.
Dalas is fine with this but not DHT. Probably some code inside the library holds.

Had to mark each sensor with radio channel because they will work with different gateways

[sharath krishna]

really cool :) what are u using to convert the AC-DC ? how u doing it ?

[axillent]

@sharath-krishna thanks

yearly in this thread you can find a schematics.
I'm using here SR10. Many alternatives were discussed here http://forum.mysensors.org/topic/687/230v-power-supply-to-arduino

I've found a solution to my problem with DHT. I put delay(500) at the beginning of setup().
This is needed to stabilize DC before initializing DHT.
Alternatively a 4.7uF capacitor can be connected between RESET and GND

[axillent]

This is my combined sketch with automatic detection of connected many DS18B20 and DHT11/22

#define RADIO_CHANNEL		76

#define DS18B20_PIN			A0
#define DS18B20_MAX_SENSORS	8
#define DHT_PIN				A5
#define LED_PIN				5
#define SLEEP_TIME_SEC		60

#include <avr/wdt.h>
#include <avr/interrupt.h>
#include <avr/sleep.h>

#include <MySensor.h>
#include <SPI.h>
#include <DallasTemperature.h>
#include <OneWire.h>
#include <DHT.h>

// DS18B20
OneWire oneWire(DS18B20_PIN);
DallasTemperature	sensors(&oneWire);

MyMessage msgHum(0, V_HUM);
MyMessage msgTemp(0, V_TEMP);

struct {
	struct {
		uint8_t	count;
		float	lastTemperature[DS18B20_MAX_SENSORS];	
	} ds18b20;
	struct {
		DHT		sensor;
		uint8_t	count;
		float lastTemp;
		float lastHum;
	} dht;
	MySensor gw;
} var;

ISR(WDT_vect) {
}

void setup()
{
	wdt_disable();
	//delay(500);

	pinMode(LED_PIN, OUTPUT);
	digitalWrite(LED_PIN, HIGH);

	// init mysensors
	var.gw.begin(NULL, AUTO, false, AUTO, RF24_PA_LEVEL,RADIO_CHANNEL);

	// init dalas
	sensors.begin();
	var.ds18b20.count = sensors.getDeviceCount();
	if(var.ds18b20.count > DS18B20_MAX_SENSORS) var.ds18b20.count = DS18B20_MAX_SENSORS;

	// init dht
	digitalWrite(LED_PIN, LOW);
	var.dht.sensor.setup(DHT_PIN);
	float temperature = var.dht.sensor.getTemperature();
	var.dht.count = (isnan(temperature))?0:1; 

	var.gw.sendSketchInfo("WallCombined", "1.0");

	// present ds18b20
	for (int i=0; i<var.ds18b20.count; i++) {
		var.gw.present(i+2, S_TEMP);
	}
	if(var.dht.count) {
		var.gw.present(0, S_HUM);
		var.gw.present(1, S_TEMP);		
	}
	var.gw.debugPrint(PSTR("Init of combined sensor: %d ds18b20 sensors, %d dht sensors\n"), var.ds18b20.count, var.dht.count);
	for(int i=0; i < var.ds18b20.count + var.dht.count; i++) {
		digitalWrite(LED_PIN, LOW);
		delay(500);
		digitalWrite(LED_PIN, HIGH);
		delay(1000);
	}
}

void loop()
{
	// Process incoming messages (like config from server)
	var.gw.process();

	// Fetch temperatures from Dallas sensors
	if(var.ds18b20.count) sensors.requestTemperatures();

	// Read temperatures and send them to controller
	for (int i=0; i<var.ds18b20.count; i++) {
  
		// Fetch and round temperature to one decimal
		float temperature = static_cast<float>(static_cast<int>((var.gw.getConfig().isMetric?sensors.getTempCByIndex(i):sensors.getTempFByIndex(i)) * 10.)) / 10.;
  
		// Only send data if temperature has changed and no error
		if (var.ds18b20.lastTemperature[i] != temperature && temperature != -127.00) {
	  
			// Send in the new temperature
			var.gw.send(msgTemp.setSensor(i+2).set(temperature,1));
			var.ds18b20.lastTemperature[i]=temperature;
		}
	}

	if(var.dht.count) {
		boolean metric = var.gw.getConfig().isMetric;
		float temperature = var.dht.sensor.getTemperature();
	
		if (isnan(temperature)) {
			var.gw.debugPrint(PSTR("Failed reading temperature from DHT\n"));
		} else if (temperature != var.dht.lastTemp) {
			var.dht.lastTemp = temperature;
			if (!metric) {
				temperature = var.dht.sensor.toFahrenheit(temperature);
			}
			var.gw.send(msgTemp.setSensor(1).set(temperature, 1));
		}

		float humidity = var.dht.sensor.getHumidity();
		if (isnan(humidity)) {
			var.gw.debugPrint(PSTR("Failed reading humidity from DHT"));
		} else if (humidity != var.dht.lastHum) {
			var.dht.lastHum = humidity;
			var.gw.send(msgHum.setSensor(0).set(humidity, 1));
		}
	}

	digitalWrite(LED_PIN, HIGH);
	delay(5000);
	digitalWrite(LED_PIN, LOW);
	delay(500);

	// sleep
	Serial.flush();
	var.gw.powerDown();

	for(int wdt_count=SLEEP_TIME_SEC; wdt_count > 0; wdt_count--) {
		wdt_enable(WDTO_1S);
		WDTCSR |= (1 << WDIE);
		set_sleep_mode(SLEEP_MODE_PWR_DOWN);
		sleep_enable();
		sei();
		sleep_cpu();
		sleep_disable();
	}

	wdt_disable();
}