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MQ7 and humidity

moskovskiy82 last edited by

Running 3 sensors with MQ7 i have noticed a linear dependency on humidity. Wonder if that is noraml or should be corrected (considering that i only want them to be the smoke sensor)
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epierre Hero Member last edited by

for me it has impact on the accuracy of readings... if we can speak of accuracy on MQ series sensors...
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I bought the Every because it implied it was backward compatible with the nano. No, it's not, as we found out. Be that as it may, any word on a getting the Every working with mySensors?
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I am new in this forum and I have a question regarding mysensors and iobroker. I did not work with mysensors up to now. Since some weeks I use iobroker installed on a raspberrypi. Now I want to integrate my 433 Mhz doorbell in iobroker. I know, that there is an adapter for mysensors in iobroker. My question is: Is it possible to get a notification in iobroker if someone is pressing the button on my doorbell? As I understood, I have to connect the receiver to an arduino nano and connect the arduino to my rasberrypi on which iobroker is running.
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I have success! (oops, that's suppose to be Timer1) I only sample for 1/60 of a second. What I did was to back up all the timer registered I used and then resorted them after I was done sampling. (As opposed to initializing the registers in setup and then starting the timer when needed.) Now I have a Nano sampling the data and sending it to a MySensors Gateway on an RPi3B+ which then sends it to an MQTT broker runing on an old laptop. Also running on the laptop is Home Assistant running inside of VirtualBox. If MySensors does use Timer1, it appears that restoring the registers allows it to be shared. //------------------------------------------------------ISR ISR(TIMER1_OVF_vect){ // interrupt service routine for overflow TCNT1 = TimerPreloadValue; // must be first line! starts the timer counting again digitalWrite(TRIGGER_START_SAMPLE_PIN,HIGH); samplesVolts[--sample]=analogRead(VOLTS_IN_PIN); // decrement before capturing samplesCurrent[sample]=analogRead(CURRENT_IN_PIN); digitalWrite(TRIGGER_START_SAMPLE_PIN,LOW); if (!sample){ // count down to zero digitalWrite(TRIGGER_START_SAMPLE_PERIOD_PIN,LOW); // indicate that sampling is complete samplingEnd = micros(); TCCR1B &= 248; // turns off timer } } //------------------------------------------------------sampleOneCycle void sampleOneCycle(){ // back up timer registers uint8_t TCNT1_b = TCNT1; uint8_t TCCR1B_b = TCCR1B; uint8_t TCCR1A_b = TCCR1A; uint8_t TIMSK1_b = TIMSK1; // configure timer which starts the sampling noInterrupts(); // disable all interrupts TCCR1A = 0; TCCR1B = 0; TCNT1 = TimerPreloadValue; // preload timer //TCCR1B |= (1 << CS10)|(1 << CS12); // 1024 prescaler TCCR1B &= 248; // turns off timer? TIMSK1 |= (1 << TOIE1); // enable timer overflow interrupt ISR // demark sampling sample = NUMBER_OF_SAMPLES; // count down to zero digitalWrite(TRIGGER_START_SAMPLE_PERIOD_PIN,HIGH); samplingStart = micros(); TCNT1 = 65535; // first trigger right away! TCCR1B |= 1; // turns on timer interrupts(); // enable all interrupts // wait for sampling to be complete while(digitalRead(TRIGGER_START_SAMPLE_PERIOD_PIN)){}; samplingEnd = micros(); // restore timer registers TCNT1 = TCNT1_b; TCCR1B = TCCR1B_b; TCCR1A = TCCR1A_b; TIMSK1 = TIMSK1_b; }
Which one should i choose? PIR or microwave sensor
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Supposedly PIR doesn't work through glass (e.g. if looking for motion through a window), whereas I presume a microwave sensor might still work.
Best VOC sensor for detecting a wide range of VOC's?
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@eiten I haven't yet made any progress on finding a good VOC sensor, but along the way I did find out something interesting regarding CO2: namely, if you sleep with your bedroom door closed at night, then the odds are good that the CO2 levels rise to surprisingly high and unhealthy levels. The better CO2 sensors are factory calibrated and never again need recalibration for the life of the sensor (usually around 10 years or so), because they are used in HVAC systems to control fresh air intake to guarantee indoor air quality. As a for instance, here is one such CO2 sensor: https://www.digikey.com/en/products/detail/senseair/006-0-0008/15790694 At around $50 for just the sensor element itself, it's not exactly cheap, but then again, I'd say it's worth it, because who wants to be burdened by remembering to calibrate their CO2 sensors? Ideally, I'd like to find a sensitive VOC sensor that also will never require calibration. Nearly all, and maybe all, of the off-the-shelf IAQ montoring stuff that you might buy for, say, $300 or less seems to require periodic calibration. For that reason, this might be one of those occasions where build is rather than buy.

MQ7 and humidity

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MQ7 and humidity

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Hardware • mysensors interrupt nano interrupts esp • • OldSurferDude

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Hardware • • NeverDie

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