Custom USB tyre pressure monitoring interface - Page 8

mrbean_phillip · 11-08-2007, 05:54 AM

Ok guys, not to hijack the thread - but there may be light at the end of the tunnel obtaining a receiver board instead of buying the complete setup - a receiver board and sensors should be a lot less expensive than what the suppliers asks for these kits.

See here

That's the datasheet for the receiver chip, an Infineon TDA5200. There is an evalution board available from Infineon for this particular transmitter, and may make it easier to setup this particular application.

@ Robby BMW: Is there a Microchip HCS515 decoder anywhere on the circuitry? Any of the boards?

This will make identifying the coding system easier....and thus helping us out to develope a good solution.

Another chip, which is very comptible with this TDA 5200 Infineon, is the Maxim Max1470 Superheterodyne Receiver - so my guess is any circuit with either of these chips should work with Robby's PIC 18F2550.

I will do some more studying to see what we can do, as I can buy the kit in Australia, but for $600 AUD - which is around USD $550- crazy I'm not.

_Dejan_ · 11-08-2007, 05:55 AM

Quote: Originally Posted by inh

Friggin SWEET!

Getting the boards made isnt a big deal at all. There are plenty of places out there where you can have em made for a few bucks a board. or we could get em made overseas with a sexy black silkscreen (or blue, or whatever) for like a dollar a piece. I've done it before.. Its like $300 up front tho for all of em, so probably not ideal.

Anyways, I'm in for a kit, or at least a good price on em if we get enough people that want em.

Im just say if someone wold like have this kit, but can't build it because he don't have knowledge I will help him with build USB controler or If he want complete build...

I think we won't get from any manufacturer builded TPMS kit with USB support for low price because there is not a lot of people who will buy it and this standalone TPMS will buy more people...

P.S. Maybe we will have luck and get any cheap TPMS with USB

thwack · 11-08-2007, 06:15 AM

mrbean_phillip

Have you looked around, I have found a few other things that are interesting:
http://www.freescale.com/webapp/sps/...&tid=tAtaxTPMS
http://www.freescale.com/webapp/sps/...02Wcbf123FQ1Dg

With these two products together or separate this could get quite cheap. Chip prices on these start at $6 for volume (obviously we cannot get them as cheap as that)

Cheers
Thwack

mrbean_phillip · 11-08-2007, 06:27 AM

@ Thwack: Yep, there's quite many different versions available, but I am trying to stick to something that will be fully compatible with Robby BMW's USB interface- otherwise we need to redo everything, which will taake so much longer, time I really don't have.

@ Robby: seems the setup you have uses ASK (amplitude shift-key) modulation....there's also FSK (frequency) and PSK (phase) modulation available.

So, we're getting closer to your setup in terms of what receivers to lookout for....

Any additional input you have, as you have quite thoroughly studied this...

juve021 · 11-08-2007, 11:02 AM

UPDATE on the kit:

I will be receiving my kit today so I'll try to take some pics of it and post, just to verify its the same one as Robby used.

Also, I've etched Robby's circuit onto a board with the famous iron-on/laser-jet/photo paper method and it worked great! Next up: drill the holes, score the board and populate!

Lastly, I have final discount prices on the kit for those of you interested, please contact me for details.

Robby BMW · 11-08-2007, 12:47 PM

Quote: Originally Posted by mrbean_phillip

@ Robby BMW: Is there a Microchip HCS515 decoder anywhere on the circuitry? Any of the boards?

No, there are only a PIC 16C621A used for handling and decoding the received signal, a PIC 16C926 used to drive the LCD display, an EEPROM 24C02W6 I think used to store the data and of course a TDA 5200 used in the RF part.

inh · 11-08-2007, 12:56 PM

Looks like the receiver board from the third eye just spits out the raw data, and robby's PIC decodes it..

Which means we buy the TDA5200's, build the board and robbys circuit, and then order $100 worth of in-wheel sensors =] There! We've already cut costs in half!

LYHTSPD · 11-08-2007, 02:02 PM

I would much rather see a home-grown solution anyway. The problem with taking the pre-built unit and hacking it is that makes you dependant on the manufacture and supplier of the other unit. Plus, you are buying a $250 item and not using half of it.

I mentioned earlier that I can get a hold of a couple of different TPMS reciever units. I can get an 08 Honda, 08+ Kia, and a few others. Robby, if you want me to send you some of them, just let me know. This may help in developing our own version of this thing.

vicky_obee · 11-08-2007, 02:15 PM

Well if some 1 can get me the whole working module/kit at a reasonable price i would like to have 1 as well pls

turbocad6 · 11-08-2007, 02:38 PM

what I think would be sweet would be if you were able to do robbies interface & still have the display too, is this possible? tap into the data instead of diverting the data?

just curious, def not a deal breaker, but that would be cool to for some installs I think...

mrbean_phillip · 11-08-2007, 04:37 PM

Quote: Originally Posted by inh

Looks like the receiver board from the third eye just spits out the raw data, and robby's PIC decodes it..

Which means we buy the TDA5200's, build the board and robbys circuit, and then order $100 worth of in-wheel sensors =] There! We've already cut costs in half!

Exactly

That's why I want to do it this way, it would help in saving costs...

Quote: Originally Posted by turbocad6

what I think would be sweet would be if you were able to do robbies interface & still have the display too, is this possible? tap into the data instead of diverting the data?

just curious, def not a deal breaker, but that would be cool to for some installs I think...

From an electronic perspective this would be easy, as you can intercept the datastream where it heads into the factory decoder pic, and divert it to Robby's solution......then you have the best of both worlds.

Quote: Originally Posted by robbybmw

No, there are only a PIC 16C621A used for handling and decoding the received signal, a PIC 16C926 used to drive the LCD display, an EEPROM 24C02W6 I think used to store the data and of course a TDA 5200 used in the RF part

Thanx Robby, I could actually read the code of one of your pictures, the TDA5200 part that is.

I know the 16C926 fairly well as an integrated LCD driver pic, so they must use the 16C621A for decoding then.

Well, this really confirms then that we need to find TPMS receivers running 433.92Mhz, making use of FSK - so it narrows the field down a lot.....even the 315Mhz USA version receivers should work just fiine - generally 433.92Mhz is used in the EU, and 315Mhz receivers in the USA.

Just something to look at for, but it is generally just a case of changing the onboard crystal oscillator to a different speed rating, and maybe changing the 64x or 128x freq multiplier on the chip to either ground or floating....

Easy enough.

Well, I will do some reading on this on the weekend, and notify you guys of anything interesting.

Kind regards,
Beanie.

turbocad6 · 11-08-2007, 04:44 PM

Quote: Originally Posted by mrbean_phillip

From an electronic perspective this would be easy, as you can intercept the datastream where it heads into the factory decoder pic, and divert it to Robby's solution......then you have the best of both worlds.

thanks, that's the route I'm going to take with this, so the data stream won't be hurt by being tapped & feeding 2 different pics at the same time? if that's the case then this is really cool & worth the extra for the whole kit I think..

mrbean_phillip · 11-08-2007, 05:18 PM

Hey Turbocad6,
Being a digital stream it should be ok, it is the same as if sitting ontop a RS-comms link and snooping data, or, for a better example, consider a standard ethernet netowork

The data is available to anyone, but only those that needs to respond will.....so, in this case, you send the data down the link, and whoever is "authorized" to listen can.....

juve021 · 11-08-2007, 05:30 PM

Viva TPMS update:

If anyone would like to order the kit right now, you can use coupon code "3RDEYE10%" to receive an instant 10% off.

http://www.vivaperformance.com/catal...roducts_id=444

Charges will be adjusted depending upon how many end up purchasing the TPMS, meaning the more orders, the higher the discount (max discount = 25%)!

turbocad6 · 11-08-2007, 05:36 PM

cool, I just ordered mine

robbies gonna send me the pic, now I just gotta figure out how to get a board made, this is a really cool setup...

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