rickatt

Excellent Instructable. Thanks for putting in all of this detail. Someone has pointed out that you can use an OTG cable, I absolutely prefer a wireless solution like this. Thanks!

Good project! I have found that the HC-SR04 works better if you increase some of the delays. i would suggest at least a 100 to 200 ms delay after you read the distance, and increase that 2 ms delay at the start to 10ms. see if that helps.I would also suggest adding more comments to your sketch, to help explain what you are doing.Thanks!

Congratulations, this is a very interesting project. A couple of thoughts. 1) why bother with the keypad? If you just left it running, what is the worst thing that happens? you get a few extra email notifications, right? or am I missing something? 2) in your code, you mis-spelled length as lenght , you might want to do a search and replace on that3) Have you considered adding a small camera to it? I have seen several that connect to Arduino's.4) how do you power it? you mention USB but only show the battery backup. An obvious power cable would be a problem because someone could just unplug it. How did you deal with this?Thanks!

This looks very interesting, but what protection do you put in for lightning?

Folks, Joram has also done an instructable and worked out a pair of formulas for the speed of sound, with temperature as a variable. This is great work!float speedOfSound = 331.3 + 0.606 * temp; //formula for speed of sound in m/sfloat compensatedDistance = (duration / 20000.0) * speedOfSound; //duration is in us, speed in m/s. /20k gives cmhttps://www.instructables.com/id/Temperature-Compe...

Joram, Excellent work here. Where did you get the formula on calculating the speed of sound as temperature changes?Did you also find any similar formulas for how Air Pressure and or Humidity effect it?Thanks,

Sir, an excellent instructable. There is only one error. You reference a Nokia 5510 in your parts list, but everywhere else you correctly call it a 5110. If you have time it would help others if you could edit your text.Thanks.

Thank you!! that reference sheet is exactly what is needed by all of us!

What was the source and the specifics of the small DC generator that was used?

Excellent work! The only thing that this instructable could use is a clear wiring diagram. It is confusing to see a series of photos with the note to ignore all of the extra wires. Thanks!