Can a pic do several things at once?

[dhouston]

You need a USB host to receive data from a USB device. A PIC is not powerful enough to act as a USB host.

[b1arrk5]

Karen,
according to the link you provided, you could get RS-232 serial out of the gps unit using an RJ-45 connector. These are the same connectors used for ethernet connections, and you can purchase a cable that has this on one end and a nine pin serial plug on the other. You can make your own cable, but you need a tool to press the wires into the connector. You can also get PS-2 connectors, but they are harder to find and cost more. Of course you might find a broken PC keyboard, and take the cable off of it. Darrel's Instant Interrupts will be your best friend for this project.

Jerry.

[Squibcakes]

A cheaper option would be to use a hall sensor mounted on your drive shaft and have the pic count the rpm. Convert that to mph and voila! You have your speed.
(If you want to get even more fancy, you could then hook the pic into your throttle and hey presto!, you've just built a cruise control for your car. Lets see the GPS do that!!)

Good luck.

Squib

[karenhornby]

A cheaper option would be to use a hall sensor mounted on your drive shaft and have the pic count the rpm. Convert that to mph and voila! You have your speed.
(If you want to get even more fancy, you could then hook the pic into your throttle and hey presto!, you've just built a cruise control for your car. Lets see the GPS do that!!)

Good luck.

Squib

I would have considered that but I've already got something similar, its my speedometer, my reason for wanting to do the above is the accuracy of speed derived from GPS signals, where using sensors on the driveshaft or anywhere else will never be anywhere near accurate due to tyyre sizes, and even the tyre pressure dropping would change the speed reading's accuracy thats why I ruled out sensors on the cars mechanical bits

[Acetronics2]

Hi, Karen

I think you could use one and only Pic ...

Let's see ...

Speed : you can't read digits @ more than 2 Hz ... and how often can you retrieve data from the GPS ???
DS1820 : Needs around 1 sec to make it's measure ... same comment for reading.

the PWM clock also can be used as the digits Multiplexing clock ...

Controling Solenoïds : aha ... that look dealing with a turboCharger wasteGate ... which is the PWM refreshing rate 40 Hz ? 100 Hz ? 200 Hz ?

No matter ... the PWM can Handle that with little trickery ( look at the recent convenient Thread on how to do that ... on MkBasic forum !!! )

Sooo, that lets plenty of time to make calculations on temp, GPS Data, Solenoid drive ...
just have a neat "scenario" ( Organigram ) and it's in the pocket !!!

Alain

PS: Mhhhh, Blondes put their hands under car hoods now ??? That's really THE news !!!

[The Master]

Just a thought. I have a satnav and it always says im going 5mph slower than the speedometer says. I also know that the speedometer says im going about 2mph slower than i really am so the satnav is about 7mph out. I know that in theory it should be incredibly accurate but it never seems to be. Might just be my satnav though.

Are you allowed to use GPS to calculate speed? What about if you lose the signal or something else goes wrong?

My personal choice would be checking how fast the axle is rotating although i wonder if its possible to do something similar to a laser mouse.

[Acetronics2]

Speed is just to show how much speed you have won with the brand new boost and injection programmings ...

no critical functions involved ...

what did you say about planet heating ??? .... ah, it's a transmission packet error !

Alain

[Archangel]

Hi Karen,
Call me old school, I believe your speedometer can be more accurate than a GPS bird 20 miles in space. Any decent speedometer shop should be able to put it right on, plus if the car is newer than the early eighties, you can access the VSS sensor for the pulses to operate the PIC.
JS

[Squibcakes]

I would have considered that but I've already got something similar, its my speedometer, my reason for wanting to do the above is the accuracy of speed derived from GPS signals, where using sensors on the driveshaft or anywhere else will never be anywhere near accurate due to tyyre sizes, and even the tyre pressure dropping would change the speed reading's accuracy thats why I ruled out sensors on the cars mechanical bits

Well thats your call, but as others have said, this approach would be more accuate than a gps. Whats more, the car needs to be moving to get an accurate speed (and direction). It would look a bit funny when your stopped at the traffic lights and your display shows you are moving at 1mph. I guess you need to take this into concideration and perhaps using a sensor on the shaft show zero speed when the car is stopped.

Oh yeah, and as far as nmea is concerned, the pic (speed) can handle it just fine untill the you start processing very long strings where you run out of memroy.

One problem I have had though is when sitting in a waitstring($GPVTG) waiting for that string to arrive, the pic can't do anything else. In those cases you could use a second pic just.... but then it all starts to get messy.

Thats my 2c worth.

Squib

squib