Ok, then on to your next auto project. How about a arduino low tire pressure alarm? My 11 year old Buick has one built in, tells me to check tire pressure.Lefty
I'd like that too! I don't have a pressure gauge. The cheap ones all fell apart on me. How do you sense pressure? I know pressure capsules with voltage output but how do you do that on a rotating part? Now i have an idea. Put my persistence of vision display on my wheel so the dude driving next to me can honk me if he sees the message: "This dude needs more air on this tire!"
Lefty,Since you challenged me to figure this out, I'll have to ask:1) if you deflate all tires equally from equally well pressurized initial condition, will your old Buick still tell you low pressure? I don't think so, but I haven't tested that.2) if you deflate just the front tires but equally, with you get a low pressure warning?I think so, but i haven't test that.3) if you park your tire-well-pressured old Buick on a slope (Should be plenty in SF, right?), with its side doors facing the top of the slope, will you get low pressure warning?No, it seems to take some time averaging before it issues a warning after actually driving some distance.4) if for some reason you're driving your old Buick and it reports to you tire pressure is low, will stopping the car turn off the warning?Only if I turn off everything and pull the key out. Warnings can also be reset, but will return if still true, like low oil level, time to change oil, door ajar, etc.I'm thinking about a bubble level (or tilt sensor) running under the car from left to right but if you carry out the above thought experiment and get back to me, I can be more or less certain about my guess.No car has to have travels some distance before tire pressure warning is issued.BTW, I was not googling anything.Funny, after I first got the Buick I goggled and did fine the method used for my car.
I'm guessing:a) level sensor, if one side is low chances are the tyre (sp) is flatNo level sensor involved.b) rpm sensor, if one wheel is going "faster" it's got a smaller (effective) diameter, so the tyre is flatYou are getting very very warm here. However I will confuse and challenge that it doesn't use a sensor just dedicated to tire pressure warning.a) is very hard to measure accuratelyb) has to take cornering into accountI don't think cornering is a factor. It's not an alarm that comes on instantly, it takes some distance traveled.
well if it's just the rear(driven) wheels you could spot the differential gear turningORif the car has ABS there could be an output from the speed sensors...
if the car has ABS there could be an output from the speed sensors...