Parking Sensor

[korttoma]

@Dan-S. Yeah I'm sure thats true. Please post a link to the documentation if you can find it. Anyhow I guess we can agree that running this device on batteries would be difficult.

[Dan S.]

@korttoma link text

[leothlon]

@korttoma
Yea from my calculations i would need to change batteries about once a month.
And with the amount of sun here in sweden i don't think solar charger would help much sadly.

[hek]

But isn't the distance sensor rather power hungry as well?

The dist-sensor but be awake all the time taking measurements (which needs to be interpreted by the MCU).. so sleep mode is not an option on this.

[BulldogLowell]

@hek said:

But isn't the distance sensor rather power hungry as well?

You could wake it with a reed switch attached to the garage door...

door open, sense and display until steady state and go to sleep on a timeout or door closed interrupt

[TD22057]

@BulldogLowell said:

You could wake it with a reed switch attached to the garage door...

door open, sense and display until steady state and go to sleep on a timeout or door closed interrupt

I like that idea. I was planning on having garage door sensors tied in with this anyway. FYI here is a link to the ultrasonic module docs which list 15mA as the current draw.

[rvendrame]

Just to add my two cents, as I have a window nearby, I'm planning to run my parking sensor with a solar battery bank, like this one.

http://www.dx.com/p/solar-powered-13800mah-external-battery-charger-power-source-bank-silver-white-281953#.Ve8ICLTOmNM

I'm waiting for the ring now. It is the last piece missing ;-)

[msebbe]

This was fun to build :)

However, my HC-SR04 is making a high pitch sound when distance is close and a more static sound when distance is further. I have tried with 3 different modules and 2 different Nanos and 2 different power sources. Is this normal?

[Sparkman]

@msebbe It's normal for a :dog: or a bat. :laughing: Either you have really good hearing, or there's something wrong with your HC-SR04. The ultrasound is supposed to be well above human hearing range (40 KHz). My HC-SR04 is quiet and I don't hear any sound from it.

[BulldogLowell]

@msebbe

building on @Sparkman , perhaps it is some kind of resonance... something attached with a natural frequency that is excited by the vibrations of the speaker.

[hek]

@msebbe

I could hear mine as well when being close to it.

[msebbe]

@Sparkman

It is correct that I have really good hearing.. But if I use the distance sensor sketch the HC-SR04 is not making any sound at all, first now with this sketch I hear it. Could it have something to do with the LED-strip I got from china?

[Dan S.]

Was checking out operation of parking sensor after changing MAX_Distance to 200 from original 100--wanted earlier start from wall. Also changed the Panic distance to 60--more space from wall during testing. Noticed that the led ring did not start from 1 pixel and increase from there as the distance closed. It started at 7 lit pixels. Examined the formula for newLightPixels and made a change which corrected this.

The current newLightPixels formula is:

int newLightPixels = NUMPIXELS - (NUMPIXELS*(displayDist-PANIC_DISTANCE)/MAX_DISTANCE);

The portion of the newLightPixels formula (displayDist-PANIC_DISTANCE)/MAX_DISTANCE) is intended to map the interval between PANIC_DISTANCE and MAX_DISTANCE to the interval (0,1). In other words, when you are at the PANIC_DISTANCE it should calculate to 0 and when you are at MAX_DISTANCE it should calculate to 1, advancing linearly between the two values as the distance closes and vice versa. Clearly when a displayDist = PANIC_DISTANCE, the numerator of the division of the formula calculates to 0. However when displayDist = MAX_DISTANCE, it does not calculate to 1.

In order to correct this I changed the portion of the formula to:
(displayDist-PANIC_DISTANCE)/(MAX_DISTANCE-PANIC_DISTANCE))
Note the only difference is subtracting the PANIC_DISTANCE from the MAX_DISTANCE in the denominator. Now when the displayDist = MAX_DISTANCE, the formula returns the value 1. So the proposed new newLightPixels formula is:

int newLightPixels = NUMPIXELS - (NUMPIXELS*(displayDist-PANIC_DISTANCE)/(MAX_DISTANCE-PANIC_DISTANCE));

I tested it both by plugging values into the formula and in operation of the Parking Sensor. Now the leds climb smoothly from 0 as you enter the MAX_DISTANCE zone. rather than starting at some number other than 1 (7 in my case).

[Lawrence Helm]

Cool, I had this happen as well, so great fix! Now all I need it to do is talk to domoticz, not picking it up yet... :)

[Dan S.]

Have one more proposed change to parking sensor code. Noticed that even when I was standing still there seemed to be quite a few changes in number of leds lit. In checking the internet, learned that variability of distance readings was particularly a problem for those using the sensor in robots. The preferred solution seemed to be taking the median of several readings.
See:
http://blog.microcentertech.com/2013/05/minipingbot-construction.html

Fortunately, the Newping library has a built in function to address this issue by taking the median of several readings (default = 5). So I modified the code as follows:

// int fullDist = sonar.ping_cm(); original code
unsigned int fullDist = (sonar.ping_median() / US_ROUNDTRIP_CM);
// Get average distance for 5 pings, convert to cm
// US_ROUNDTRIP_CM = distance sound travels in cm/sec

As a result, the jumping around of the number of leds appears to have decreased significantly and the response is much more stable. Hope this helps others.

[msebbe]

@Dan-S. Thanks for your investigation! I made the changes and it seems to work well!

About the high pitch sound I mentioned earlier; I changed NEO_KHZ400.

Adafruit_NeoPixel pixels = Adafruit_NeoPixel(NUMPIXELS, NEO_PIN, NEO_GRB + NEO_KHZ400);

to

NEO_KHZ800

This removed the annoying high pitch sound :D

[Dan S.]

@msebbe Glad everything worked out well for you. Your comment made me think about changing mine to 800 also. From what I could glean from looking on the internet, 800 is more appropriate for newer devices, e.g., the led ring. So I am going to change to 800 also. Thanks.

[wergeld]

Just built this with my 4 year old. She loved it! She did the project management and directed me which wire goes where. Got to start them young!

I was really shocked at the brightness of the LED ring. I mean, I knew it would be bright from looking at the videos, but wow.

My setup was to connect my UNO to the PC, load code and branch power directly from the UNO's 5v pin. I had no cap or resistor in place either (neither was there a radio hooked-up). This was just a bench-top proof of concept and it worked right out the box (after I soldered leads to the ring). I went through all the adafruit example codes and worked without a hitch. I may, or may not, exceeded WAF level 10. Now she is giving me more projects for these "neopixel" lights.

[hek]

My girls like liked the neopixels as well ;)

[Dan S.]

Had some issues with the operation of my parking sensor which I resolved and now it seems to be working perfectly.
Thought I would pass on what I did in the hope that it might help others having the same problem.

There were 2 issues.

The first issue was random lighting of the led ring after the car was pulled out of the garage and the door was closed. My guess was that the sensor, in the absence of having the solid car to bounce off of, was picking up stray sensor ping echoes from other objects in the garage. Checking on internet revealed that others using the HC-SR04 Distance sensor had experienced this problem. Checking further, I discovered that there were updates to the NewPing library, the latest being version V1.7 and specifically that V1.6 included an update to the sonar.ping_median function used for distance measurement in the parking sensor code. The MySensors library current version is V1.5. After I updated to V1.7 I no longer had random readings when the car was not in the garage. First problem solved.
bolded textSo I would recommend updating to NewPing V1.7.

I then reinstalled the parking sensor in the garage for further testing. Everything appeared to be going well but when I returned to park my car in the garage later in the day I was greeting by the led ring flashing bright red with all its leds which is supposed to be a panic signal that the car was parked as close as it should be. But I had just entered the garage and was not anywhere near the range of being parked. Took the sensor down and brought it in for testing. Found out that everything worked fine except if it was left on in the condition where it was not sensing any object in range for an extended period of time, it went into the flashing led mode. Too me it had the symptom that given enough time, a variable was being overrun (an integer variable exceeding its capacity). Checking over the code I noted the following lines:

if (displayDist == 0) {
// No reading from sensor, assume no object found
numLightPixels--;}

So everytime the displayDist = zero (and it is zero when no object is detected) numLightPixels is decremented by 1. So if there is no car in the garage (and since I had fixed the random detection problem), the sensor returns a steady stream of zeros to indicate there is no car in the garage and the numLightPixels is decremented with no limit. Given enough time it will eventually decrement to -32,768 at which point it rolls over to +32,767 and at that point the red leds will all flash in the panic mode. To fix this, I changed the above code to read:

if (displayDist == 0) {
// No reading from sensor, assume no object found
//Make sure you don’t go below zero
if (numLightPixels>0) {
numLightPixels--;}

So now it won’t decrement numLightPixels below 0. That solved the problem.

There is also one related efficiency change I made. At the beginning of the loop there is code to skip 10 zero readings:

if (displayDist == 0 && skipZero<10) {
// Try to filter zero readings
skipZero++;
return;
}

I changed that code to skip all zero readings if numLightPixels is less the one (i.e., 0), since if numLightPixels is at zero all of the pixels are already off and if the sensor continues to read zeroes, they should all be skipped (don’t go through the rest of the loop) until a nonzero reading is obtained (something is found).

if (displayDist == 0 && numLightPixels<1) {
// Filter zero readings
return;
}

Mounted the sensor in the garage again and now everything works perfectly. Hope this helps someone else.