Custom USB tyre pressure monitoring interface

**Robby BMW** · 07-12-2008, 05:16 AM

**bes51659** · 07-12-2008, 06:56 AM

Thanks! Getting clearer :-)

**Blankstar85** · 07-13-2008, 02:43 AM

ok cool thanks

**meddler** · 07-13-2008, 11:33 PM

how much did you pay for your kit? and where did you get it from?

**steven765** · 07-13-2008, 11:41 PM

I paid 350US for the 5 sensor kit, would have been 325 but paypal bent me over on the currency conversion.

I bought the last one from another member here. He may have one 4 sensor kit left based on what he commented before I'm not sure.

I also just tried moving the sensors a few feet away. The head unit seems to respond faster now. Mayyybe it didn't like them being that close. I've been re running the same tests from a distance and it seems to respond quicker. Weird, but I think i feel confident installing it tomorrow with my new car sneakers

Robby Do you have any close up pics of where to cut the board? The other tutorial site doesn't have any close up pics of where to cut :/
I also have a Lynx RF receiver laying around 433.92 MHz, Think it will pick up the tires, I need to get the analyzer you used to see if it's receiving. Might be a way to get rid of cutting the board. Thoughts comments?

**a__l** · 07-14-2008, 03:37 AM

2 Robby BMW,
Hi Robby, if you don't mind I would like to ask you one questions concerning Sensor state in Storage mode .....
In case of the pressure in the wheel is absent will sensor sent data (low pressure) permanently or it will go in the "sleep" mode if during the long period the pressure is still absent (I am trying to follow exactly your idea, but implement the Car-PC interface for WAECO TMPS) ... LYHTSPD mentioned about it.

And also the second question about data encoding:
Is your device using the Differential Manchester encoding that is specified here -> http://en.wikipedia.org/wiki/Differe...ester_encoding
?

The 3-nd one if you don't mind :-)
Why did you decided to use Transistor between Receiver's signal and PIC? Just for inverting or the output signal is not 5V compatible? ( I mean, why didn't you put in this signal direct into PIC)

**Robby BMW** · 07-14-2008, 11:53 AM

Originally Posted by steven765

Robby Do you have any close up pics of where to cut the board? The other tutorial site doesn't have any close up pics of where to cut :/

You can give a look at mrbean_phillip's post, it contains a few detailed pictures of how to do the TPMS setup.

Originally Posted by steven765

I also have a Lynx RF receiver laying around 433.92 MHz, Think it will pick up the tires, I need to get the analyzer you used to see if it's receiving. Might be a way to get rid of cutting the board. Thoughts comments?

Theoretically any receiver with the following characteristics could work:
Frequency: 433.92MHz
Demodulation: ASK
RF input sensitivity: < –107dBm
Bandwidth: > 40 KHz

**Robby BMW** · 07-14-2008, 12:12 PM

Originally Posted by a__l

2 Robby BMW,
Hi Robby, if you don't mind I would like to ask you one questions concerning Sensor state in Storage mode .....
In case of the pressure in the wheel is absent will sensor sent data (low pressure) permanently or it will go in the "sleep" mode if during the long period the pressure is still absent (I am trying to follow exactly your idea, but implement the Car-PC interface for WAECO TMPS) ... LYHTSPD mentioned about it.

Only the sensors manufacturer can answer at this question with certainty, however, for what I was able to see, every time the pressure is below 1.5 bar, the sensor goes back in sleep mode.

Originally Posted by a__l

And also the second question about data encoding:
Is your device using the Differential Manchester encoding that is specified here -> http://en.wikipedia.org/wiki/Differe...ester_encoding
?

Yes, the device uses a differential Manchester encoding.

Originally Posted by a__l

The 3-nd one if you don't mind :-)
Why did you decided to use Transistor between Receiver's signal and PIC? Just for inverting or the output signal is not 5V compatible? ( I mean, why didn't you put in this signal direct into PIC)

The transistor has the dual function to invert the signal and bring it to 5V, as the output from the receiver is about 3.8V.

**wiggy** · 07-14-2008, 01:09 PM

I was wondering if any body can shed some light on some problems im having.

Firstly i purchased the kit from LYHTSPD ( 5 sensor kit - and 4 additional sensors)

I am using centrafuse 1.47 with TPMS version 0.5.0.1

Ok , i started off with a clean pic and tryed pairing the sensors .1 sensor will pair , and if i adjust the pressure in the valve it will move up / down within a reasonable time.

When i try to pair the second sensor , sometimes it wont other times as soon as i click pair and go to let some air out ..it pairs it's self without me touching the valve (or air)

Other times it will let me pair 2 , but the pressure readings seem to be the same and they dont change either.

I have reset the pic many times and tryed again.I have positioned the reciever next to each wheel as i try to learn ( does any one know what distance it will work at).

It seems each time i try something different happens.

I have tryed uninstalling TPMS software , re installing , but nothing.

I have not bothered even trying the second set of wheels yet !! ..all the valves were fitted proffesionally and they are holding air ok.

The most i got to pair was 3 once , but all the pressure values were reading the same , even though i set them all 10 psi different..

Any body shed any light on this ...i have a second set of wheels for off roading and i was hoping that a quick set up is all i would have needed when i swap my wheels over ...looks like i will have trouble each time !!!