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Hello, I am wanting to display MPG on an old VW camper van. Does anybody know of a hall effect flow sensor that can report the very low flows found in carburetors please.

terryrow last edited by

Hello, I am wanting to display MPG on an old VW camper van. Does anybody know of a hall effect flow sensor that can report the very low flows found in carburetors please. Alternative suggestions always welcome.
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arden last edited by

guess no odb port?
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mpg meter for vw camper van 1

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Does MySensors require Arduino Timer 2?
Hardware • mysensors interrupt nano interrupts esp • • OldSurferDude

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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; }
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.
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@wrendral said in "Remote Irrigation with LoRaWAN: LM27313 Challenges and PCB Design": I will go with a Li-Po Battery type: 304048 3.7V 1200mAh Might work, but maybe the internal protection will trigger with the high current peaks. I'd suggest you plan a 0 Ohm, (2512/THT) resistor as R2 and then replace it with a 100Ohm/1Watt if the protection triggers.
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Hardware • • Robert Leverett

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Hello, I am wanting to display MPG on an old VW camper van. Does anybody know of a hall effect flow sensor that can report the very low flows found in carburetors please.

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Over the air updates
General Discussion • • ToSa

hlk-pm01 are to noisy for rfm69?
Hardware • • Tmaster

Does MySensors require Arduino Timer 2?
Hardware • mysensors interrupt nano interrupts esp • • OldSurferDude

Best VOC sensor for detecting a wide range of VOC's?
Hardware • • NeverDie

"Remote Irrigation with LoRaWAN: LM27313 Challenges and PCB Design"
Hardware • • wrendral

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Hardware • • Robert Leverett

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Hello, I am wanting to display MPG on an old VW camper van. Does anybody know of a hall effect flow sensor that can report the very low flows found in carburetors please.

Suggested Topics

Over the air updates General Discussion • • ToSa

hlk-pm01 are to noisy for rfm69? Hardware • • Tmaster

Does MySensors require Arduino Timer 2? Hardware • mysensors interrupt nano interrupts esp • • OldSurferDude

Best VOC sensor for detecting a wide range of VOC's? Hardware • • NeverDie

"Remote Irrigation with LoRaWAN: LM27313 Challenges and PCB Design" Hardware • • wrendral

Sensors and more Hardware • • Robert Leverett

11Online

11.4kUsers

11.1kTopics

112.7kPosts

Over the air updates
General Discussion • • ToSa

hlk-pm01 are to noisy for rfm69?
Hardware • • Tmaster

Does MySensors require Arduino Timer 2?
Hardware • mysensors interrupt nano interrupts esp • • OldSurferDude

Best VOC sensor for detecting a wide range of VOC's?
Hardware • • NeverDie

"Remote Irrigation with LoRaWAN: LM27313 Challenges and PCB Design"
Hardware • • wrendral

Sensors and more
Hardware • • Robert Leverett

11
Online

11.4k
Users

11.1k
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112.7k
Posts