[LPG2CV]

regarding knock sensor, The signal has to be processed in the firmware, thats the part still under development

[Mouch]

Allright, thanks for the heads up

The V04 had the same function as the ADC, right? So if I want 6 channels I have to build it 6 Times?

Or I might make a small PCB that will have the ADC together with the hardware to accomodate 6 sensor inputs which looks like the max for this ADC

[jonbill]

Also - I think the knock input to Speedy is set to be the output of a knock controller, not a knock sensor.
(analagous to the wb02 setup)

[PSIG]

The circuit below should be familiar to the others posted, but is the minimum pullup circuit for a grounding sensor such as a temperature thermistor. The other bits in the other posts (diodes or clamp, input resistor and caps) are to protect the Mega from over-voltage, negative voltage, excessive current and noise. So, the circuit below will technically function, but is prone to damage or noise in a "dirty" automotive electrical system.

generic_analog_input.jpg (25.76 KiB) Viewed 1732 times

[Mouch]

Thanks for all the responses! Also for making it more understandable

Ok, so I think this will work.

First time using EasyEDA so bear with me

I've made this circuit for the analog input, will this work?

[JHolland]

The knock sensor doesn't need a pull-up but it would be a good idea to have something like 47k in case it becomes disconnected. What other sensors are you intending to use? that will dictate what circuitry you use for most sensors you should increase the value of the series resistor to 4k7 and increase the capacitor to 1uF, that will reduce noise considerably, I don't know why Speeduino uses those values they make no sense but it never gets corrected.

[Mouch]

Primarily I want to use NTC's (2x oil temp) and one knock sensor module output (0-5V).

The rest of the inputs are not in use for this unit of Speeduino.
On the next project I want to add some Hall sensors for wheel speed and maybe an display outout.
I think this will be to much for the Speedy so I'm fidling with the GPIO but the communication is not yet there.

For now I'll stick with 2 NTC's and a 0-5v input from the knock detection unit.

If you say 4k7 resistor, you mean in total or per resistor?
If you say 1uF capacitor, you mean in total or per capacitor?

[JHolland]

I don't know what the sampling frequency is for the additional inputs, I do know its not going to be fast, maybe 10Hz. The bandwidth will be half the sampling frequency so your input filter, which is currently 470R/1uF giving a bandwidth of 1.5kHz, is quite inappropriate, every noise frequency from half the sample rate to around 20kHz is going to aliased in to the signal.
The Mega doesn't have a very high quality ADC so you need to compromise between noise and speed/accuracy. If you substitute 4k7 for each 470R and 1uF for each 220nF then you get a bandwidth of around 35Hz which will cut out a lot more noise, its probably still a bit high but you could go up to 7.5k for the resistors or increase the size of the capacitor. 1uF should ensure that you will still get enough charge into the ADC sample/hold cap to get 8-bit resolution with the worst case ADC input impedance.

[Mouch]

Alright!!!

I've got sensor input! Made the version 4 variant on a breadboard and it's working.
The gauge changes with temperature.

Now how to change the gauge....
Can anyone point me in the right direction?

I'v tried it through "Custom Channel Editor" but when I change the values (0V=> 30, 5v=>300) it still shows the digital output (in my case 630 at 30degrees).

What am I missing?

[Mouch]

Forget the last question, I was 2 quick in the digital pen.

Found it! Was going on the wrong output channel (auxingauge0 in stead of custom)