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1  Using Arduino / Sensors / Re: Need ideas on tachometer using ignition on: February 18, 2013, 03:27:24 pm
Hello i'm also interesting this project however i had another question to very related the subject.

İs there any way to read ignition voltage from plug cable using with arduino.

2  Using Arduino / Sensors / Re: Strange Analog Input Problem on: February 18, 2013, 03:23:33 pm
Hello again,

Using 10k resistor does not change much. Just output range changed. After resistor sensor start to give 3. ish v and down to 1.9 ish v.

Anyway today one of our friend which has some car electronics repair experience suggest, maybe ampere of the sensor output was too low. So aduino analog voltage noise (which we detect every analog port of arduino) generates resistance against sensor output.

is this make any sense ?

3  Using Arduino / Networking, Protocols, and Devices / Recommendation for Bluetooth connection on: February 13, 2013, 02:11:12 pm

My project uses arduino for sensor reading then monitoring on pc.

With using usb connection everything fine.

However we want bluetooth connection for our project.

We use Olimex 328 for arduino and naturally we choose Olimex MOD-BT for our bluetooth solution (availability in our country and price). But that MOD-BT thing was not working. We do not have extensive electronic knowladge. It seems setting up this thing was beyond our ability. Even we can't determine that module was fryed or not. Manufacturer support isn't. They even can't reply questions in their forums.


What we need is. Simple.

We want read arduino serial output from bluetooth.

Could you recomend us a solution for our needs.

4  Using Arduino / Sensors / Re: Strange Analog Input Problem on: February 13, 2013, 02:03:18 pm

I got it, sensor circuit must use arduino ground.

Both circuits are commercial and closed source. Second one (which does not work) was very small and half price smiley.

Thats why I desperately looking for help.


Thanks lot for your time.

My humble regards
5  Using Arduino / Sensors / Re: Strange Analog Input Problem on: February 12, 2013, 05:01:31 pm

I mean both sensor grounds and arduino ground connected to AC Power ground.

Well if we connect grounds to arduino ground. We did not get any stable meaning results. In old  device this setup was working.

Interesting thing was with this setup. It works to half way.
6  Using Arduino / Sensors / Re: Strange Analog Input Problem on: February 12, 2013, 03:16:01 pm
Hi Krodal,

Many thanks for replying.

We setup same kind but different made sensor befor and run without any problems. Sensors are highly sophisticated, these 0-5v linear outputs are mostly used on independent displays. We do not expect any spikes or similar errors (of course there is always be possible and if this happen it should have to our sensor circuit spesific).

No we do not use AREF in any kind.
I set the


and remove it after your advice nothing changed

We measure voltage both arduino and multimeter.

Arduino is Olimex 328

Sensor is custom made wideband reader. It has 2 ground one for sensor one for sensor heater.

We power arduino from usb and power sensor from 12v adaptor. Both sensor grounds plus arduino grounds was connected to adapter ground. Anykind of ther ground setup generate veird readings from analog input. Arduino input was a5, (also I change it for testing nothing changed)

The other device has one ground and when we connect the arduino ground it works withouth any problem.

Also I maybe can't explain problem clearly.

Sensor generates 0 to 5 volt linear output. when we connect to arduino it works 5 volt to 2.24 volt and does not go bellow. under normal circumstances it should go to 0v or 0.1v.

However it swings 5v to 2.24v

Best regards...
7  Using Arduino / Sensors / Strange Analog Input Problem on: February 11, 2013, 05:52:00 pm

We are trying to connect 5v linear output from sensor to arduino analog input.

Everything works except. Sensor output was stuck at 2.24v. When we disconnect ground from arduino and check the sensor output with multimeter everything works well.

Sensor has one 12v volt input, one ground for sensor circuit one ground for sensor itself. We wire sensor with external adapter + to 12v input, both ground and arduino ground connected to external adapter.

If we do not connect arduino ground sensor reading from arduino was unstable. However sensor linear output works as expected.

Sensor circuit was propetary and we do not know anything about it. Producer looks helpful and does not interesting with arduino usage.

So ? is there any work around  and or explanation for this problem.

Our best regards.
8  Using Arduino / Sensors / Re: Analog Read from empty pins display bigger than 0 on: November 08, 2012, 12:19:28 pm
Actually it was not a plain sensor. I'im trying to read my Wideband controller (a commercial one) linear output form arduino analog pin.

Sensivity is important. My readings are not lienar. It sends values like waves which made me nervous and I want to make sure nothing was intefere the signal.

My Best regards
9  Using Arduino / Sensors / Re: Analog Read from empty pins display bigger than 0 on: November 07, 2012, 05:32:59 pm
Oh no. Never ending random generator debate detected !!!  smiley-eek


To read 0 from analogRead I have to connect analog pin to ground with pull down resistor.

Is it effect my sensor output ? or shall I do something extra for my sensor ?

10  Using Arduino / Sensors / Analog Read from empty pins display bigger than 0 on: November 07, 2012, 04:32:10 pm
Hi there,

I had a electronic sensor which had 0-5v linear output. My aim read this value from arduino and send to pc via USB.

I try to read via analog read and failed.

After some trial error I found my empty analog pins shows values. Also A4 and A5 displays constant 1023 value.

I though pins have to show 0.

My Board is olimex-328


void setup() {
  analogReference(INTERNAL); //analog in can only go up to 1.1v! 

void loop() {
  int sensorValue = analogRead(4);
  Serial.print("sensor = " );                       
  Serial.print(" Voltage=");
  delay(100); // wait 1/10 of a second 

double voltage(int analogIn){
  double voltage = (analogIn/1023.0) * readVcc();
  return voltage;

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__)
    ADMUX = _BV(MUX3) | _BV(MUX2);
    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

I found some posts about arduino ground may affect analog read values.

What is my problem.

Also is there any way to detect internal voltage. (3.3 or 5v)

My Best Regards
11  Using Arduino / Motors, Mechanics, and Power / Re: Reading Secondary Ignition Voltage from car ignition systems on: May 11, 2012, 08:01:13 pm
Thanks for reply,

It seems, there is no basic way (I mean find xyz sensor fit the ardunio or one of those multi sensor shields and program it).

I have some programming background and electronics stil look like black magic.

Could you lead me any useful document for covered this topic.

My best regards.
12  Using Arduino / Motors, Mechanics, and Power / Reading Secondary Ignition Voltage from car ignition systems on: May 11, 2012, 12:52:19 pm
Hi there,

I want to use Arduino to read a car secondary ignition voltage.

Last week I search everywhere and I have not any clear answer to how to read secondary ignition voltage from ignition plug cables.

I had a handheld device which can do this and I need this data in my computer.

My handheld device manual says, it has  capacitive sensor to read secondary ignition from ignition plug cables.

Anyway, secondary ignition voltage can up to 50kv dc.

Is there any way to read this data using with Arduiono.


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