No, but Hanks could.

The Orion trackside unit has an IR receiver but no IR transmitter, so it could not communicate with a Palm. In fact, it is not just as simple as using an IR transmitter to communicate with a Palm... there is a lot more going on.

Hank,

You seem to have a good understanding about a lot of this. Do you have any designs for a smallish 100 Hz datalogger circuit that would do 2-4 channels (SE or Diff)? I have looked, but they either sample at about .5 Hz or need power from a PC (USB powered).

I will pay :)

Thanks
SS

The thing to do would be to start with a microprocessor and attach a large wad of EEPROM. You can upload to a PC via serial. Sense the servo commands from the pins, use an A/D chip for voltage and a Hall sensor for current. Sounds like a good project, but not one I want to tackle while the other things are unfinished...

It would be pretty hard to go at 100Hz, the amount of data to be stored would be huge. That is about 200K of memory required per minute. It is 400 pieces of info per second so you are actually looking to operating at close to 4000Hz with the overhead (read, convert, write, etc.).

Something that samples at 5 Hz would be easy with 10Hz not much harder. Of course it would all have to be custom built... very doable but would take some development time. To make sure there are no problems a seperate battery pack would need to be used. Not really that bad as many already use a receiver pack and that could do double duty to power the unit.... 6 cells would be better then the 5 cells that are normally used.

What I am actually looking at doing is making a "real time" DAQ where the data would be transmitted via RF to a computer in real time. Then you could let the CPU run at full speed and sample as fast as it, and the program, would allow and not worry about data storage. I figure it could do 6 channels at least 50 Hz, most likely more.

Hank,

This is something that I believe could be VERY useful to R/C car racers. The Miles brothers have done something themselves, but I hear it has been fairly pricey. I would like to work this out, but circuit design is for me.

If you plan to develop this for sale, keep me posted. If not, consider what you would charge me to make a couple units.

Thanks
SS

Above post should say "microcontroller", not "microprocessor".

The plans for anything I design will be freely available to anyone. I may offer a "parts pak" that would include everything needed to make it. That would save someone from having to buy from a half dozen suppliers and would also include a circuit board to mount everything on. My guess is the cost would be less then $300

From what I've seen, you'll need at least 10Hz to see what's happening on the track. Especially for the oval guys.

I want a RPM sensor on my personal data logger... I thinnk with RPM I could tell most of what I'm missing... Voltate and Amp would be nice too, but I could likely live without that, if we were talkinga bout something cheap...

Oh wait a minute... this is the personal lap counter thread... could you throw a RPM logger in with it?

I was kind a joking in my previous post... however after I've thought about it a little more I really think that if there was a way to record RPM and tie it to the points where the car passes one of the sensors on the track I could lean alot about how to gear a car, and how to improve my driving.

In oval I would use two snesors, comming out of a corner, and the other at the end of the straightaway. You could get lap times, and sense the RPM at the fastest and slowest point on the track.... I beleive this would be a great help for oval racers... I think a simmilar thing could be done in road course as well... but it would take more sensors, and/or you'd have to work on one section of the track at a time.

Originally posted by hankster early in this thread:
My guess is you should be able to buy everything for well under $100 and most likely under $75.
Then just recently:
My guess is the cost would be less then $300

Hank, I sure would like the first price range a whole lot better than the second one.

Will it be possible to get the absolute basic version close to the original price point and then add on features which would carry it up to the second price point?

Is the price change a reflection of the cool ideas here or of the basic unit itself?

Those are two different conversations.

His LAP timer will cost < $100

The Datalogger I want to make will cost around $300.

Hope this clears it up

SS

I guess it could be made upgradable but I think that having one unit that is upgradable would be defeating the purpose of the basic lap counter. If we drive the price up to over $100 then they might as well buy the Orion or LapDragon unit.

Adding on the extra circuits on the basic unit (plus a more powerful CPU) that would be needed if we wanted to make it upgradable most likely would put it over $100.

I think everyone would be better served with seperate units. So you buy and build the basic at $75.00. When you want to move up you sell it for $50.00 (or more because it is already built) and use that towards the purchase of the DAQ.

As a note: I have all the hardware on hand to build the lap counter. It's doubtful I'll have a bunch of time to work on it this week, but plan to hit it hard next week. I hope to have a working prototype by the end of next week.

Also, I have about 75% of the hardware needed for the DAQ and a rough plan on how I want to do it.

Once we get close to having a final version or the lap timer I will be opening a new web site to support this and all other "RC Tech Series" projects. I'll announce it here when we get that close.

As I stated before, all plans, hardware lists and instructions will be posted on-line and will be freely downloadable. What I would like to do is offer a "parts pak" that would include everything needed to make the units. The advantage of buying the "parts paks" would be you would know for sure that you are getting the correct parts and you would have one place to buy everything. Otherwise you would have to buy the parts from a number of different sources making it harder to do and most likely more expensive.

May I ask what kind of chip you're using?

I'll be developing using the Basic Stamp.

That's one of the chips I considered for mine as well, since it's easy to program. But for something I wanted to make ten or more of, I didn't like the price... Then I sterted looking at what it takes to program PICs and chickened out.

For my system, with most of the brains in the trackside computer, its data transfer wasn't fast as I wanted either. Since you're not worried about multiple cars that's not a problem. And maybe I'll go back to it anyways.

I'm eager to see how it turns out...

For those who don't know...
http://www.parallax.com/html_pages/products/basicstamps/basic_stamps.asp

Yep, there are a number of problems with using a Stamp if you want to do multiple cars. It's even pushing things when making the DAQ, mainly writing to EEPROM.

That is why I decided to go with the RF transmitter for the DAQ, I think I can push out the data fast enough to keep the sample rate up. And it does eliminate the need for all the memory. I think the saving in not needing the extra memory will offset the cost of the RF end of things... plus it'll be so cool to see the data on the PC screen as the car is running. If I need more speed I can always go with the BS2-sx or BS2-p

You can use the pulsin command to measure servo/throttle positions. These should happen in succession, so you can read one, the other, then whatever other sensors you've got (voltage, current, whatever), then repeat. This will give you about a 20 ms refresh rate. You can program in a delay if you want to slow it down.

I have to recommend the Linx LC chipset for RF. It's just way too easy. Rx and Tx both just have power, signal, antenna, ground. You use the serout command from the Stamp to the tx, and feed the Rx's signal wire into the computer. It's a LITTLE more complicated than that but not much.

In fact you should find that the FreeLap first-gen receiver box is exactly the same as what you want for yours.

Yes, I know all about using PULSIN commands. Not sure what Tx/Rx set I'll use yet. There are many and some do have advantages over others. I'll most likely use the Javelin Stamp for the DAQ since it will eliminate a lot of external circuitry.

Parallax was selling Tx and Rx kits for the Stamp that were based on the Linx LC chips, but again, I didn't like the price. Those and similar, here:
http://www.parallax.com/html_pages/products/communication/rf_modules.asp

Well since everyone is talking about this I just can't keep my mouth shut. I've been working on this for two years now. You can see some of my progress at http://bigboy.slink.com/Telemetry/
. I was planning to make this a commercial product, but since Hank is doing one now for free I may scrap it. I've already got to much time and money wrapped up in it.

why dont somebody make a wheel dyno?? One that measures data from the motor and the car wheel at the same time. I think this would be more usefull than a regular dyno.

Gary,

You have some great ideas. I have used several versions of your Lap Timer and I like it. Good luck with the Telemetry system. I am afraid to ask how much you have invested in that project, but it looks SWEET!!

Your Lap Timer Beta 11 expires on 12/1/2002. Do you plan to issue another beta release or a final release?

SS

Garey, No use to stop work, I feel the more the marrier. BTW, maybe we can do something with using what I want to make and using a Palm instead of a PC... at least with the Lap Counter. I think that would be very handy feature to have.

As an added thought on the reason for using the Javelin Stamp instead of the Basic Stamp even though it is more expensive. Much of the needed software is already built into the JS. It already has an AD converter (needed for voltage and amp readings), it has a built-in timer for lap timing and the big one is the built-in power supply should be able to power everything with power from the receiver. The only problem is in 4 cell cars as the voltage is too low, but then most 4 cell racers use an external receiver pack that should work.

All of this means that very little extra circuitry would be needed. I can see a few resistors and a few caps on the circuit board and of course the additional external sensors. Should make it easy for anyone with good soldering skills to make.

The size should not be much bigger then a 24 pin DIP package which is about 1.5" long and .75" wide.

Hank, I am very interested in the completion and progress of this project. I think it is about time someone came out with at least the system and parts to make a DAQ Unit or cheaper lap timer. I was wondering however, this is a little off topic, if anyone has ever tried or considered hooking up 4 digital scales together, and wiring them through either a serial port or usb port on a pc, to get instant readings from the scale to a program that could calculate cross weight, or other usefull information pertaining to weight transfer. Maybe add other equations to calculate roll center, center of gravity, stuff like that. I understand your busy with your project and am looking forward to seeing it completed, but maybe someone else has looked into this, or has thought or will think about it? any replies appreciated, thanks. -Jeff Patch

Jeff,

Hehe... your jumping ahead a little here.... or maybe a lot. One of the projects on my list is a "portable" scale system that would use 4 small pressure pads that could be placed on any hard surface and used as a scale. It could be fed into a PC but using an LCD display would be better 'cause then you wouldn't need a PC to use it. Advantage of a PC is that the data could be stored. That actually is a pretty simple project to do. Cost about $150.00

As an expansion of that would be to build a "wind tunnel" so you could test the effect of different bodies and body placement on your car.

Lots of ideas but not enough time. :eek:

Hank, I am loving the ideas. I almost think you should get a couple of guys like your self and start your own high tech r/c equipment company. Who knows how much money you could make and how far you guys could advance the sport. Keep us posted on progess of the lap counting system and DAQ, can't wait to see them when thay are done, take care. -Jeff Patch

If I had a few hundred grand to start a company to fully develop this and market it I would... :thumbsup:

Mainly this is fun for me. If I can offer what I have found to others and they get some use out of it, that's great. Hopefully those that find the info useful will buy the "parts paks" from me so I can at least support HobbyTalk and maybe even buy a few extra RC goodies.... I'll be really happy.

The way it looks I'll have to buy at least 10 of everything to even get a 10% discount. That means for a $300 system I'll have to put out $2700.00 to buy the parts. Now lets put together some instructions, build the web site and answer questions. If I can make $300 on 10 systems a month that will at least cover the server bills to keep HobbyTalk up and running.... that's all I want anyways.

Hank, I think before you put up any cash of your own, get to a "production model" and have it ready for the Parts Pak. Then you take orders with a deposit and figure out how many will sell. That way, you're not putting up a ton of your own cash up front.

I'm not sure I'd be that interested in the DAQ, but I'll buy a lap timer from you when that's ready. :)

Oh... If you're really interested in starting up a company to make this sort of stuff, why don't you look into getting a government loan/grant to start a small business? They're looking for ways to jump start our economy and I'm sure you could get pretty decent rates on a SBA loan.

Hey Hank, any progress report for us curious folks?

Interested in how you're making out, if you've had
time to work on this more.

I would be interested in one too. :D

I have done some work on it. Got the basic programming done with a bunch of fine tuning to go. A few other things have been taking time away from it and I have not been able to do a bunch lately. Right now I need to get a few extra parts... I've been laid off since Dec. and still have not received an unemployment check from the state (applied 3 times and my application has been lost all 3 times somehow)... and it seems that the FOC (friend of the court) doesn't like when you fall more then 4 weeks behind... right now I'm just happy to be out of jail!

Sorry to hear about your luck Hank, I'm sure things will turn around for you though. I've just found this thread tonight, and I must say that I am very excited. I have been thinking about trying to implement a ir transmitter/receiver set with the M8's laptiming function, but haven't had enough time to play around with the idea(similiar to the Orion, but using the transmitter). I have to say the idea of buying all the parts and making the unit myself is very appealing to me, I'm not a electrical engineer, I do have a BS in Engineering(would be an EE if I had it to do over again:devil:) but I do have electrical background. If I can assist you in any way in this project, please let me know, I've been contemplating buying the ORION system, but like everyone else here that I can see, was displeased in it's performance for the price. Interval timing is somthing I hadn't thought of having, but would love it in a PLCS.
For now I'm just wishing that someone would incorporate a wireless network with the AMB timing system used at most tracks, so I could do my test, then download the data from the LCS to my laptop via the network.

:( Hankster, I hope things turn around for you......soon.

Just thought I would bring this thread back to the top for everyone........... Hank, how are you, have you had time to work on this project any further??????????

I've had a few bumps in the road. Most noted is that it took 7 weeks to get my first unemployment check. Needless to say that put the hurts on buying parts I needed to complete the project.

But using parts I already have I have been working on a programmable discharger. It will discharge at whatever rate you want (50 amps or more) and what cutoff you want. It will graph out the discharge curve, figure the average voltage and save the data to a file.

Not sure at this time how many samples per second will be done, right now it is doing about 50 per second which is really way more then is needed. I may cut that back to about 10 samples per second.

As a note; It uses an ESC (user supplied, any cheap ESC will work) to control the discharge rate and light bulbs (user supplied) for the load so you could, as an example, put 25 bulbs together if you wanted to discharge as high a 40 amps. The load is only limited by the number of bulbs and what the ESC can handle.

For an example I am using a load that has 20 bulbs on it. If there was no control it would discharge the pack at about 37 amps. We sense the current draw and adjust the ESC so the discharge rate is whatever is programmed into it.

I figure the cost to build, not counting the ESC (which most people have an old one laying around) and the bulbs will be about $80.00. Not a cheap project but it is an interesting one.

Sounds cool Hank... I think it may have more then one use...

Have you tried using a old stock armature as the load, dip it in ice water to keep it from going up in smoke???

I haven't tried that but any load should work since an ESC is being used to control the load. Heck, if someone wanted to make a resistor bank that would work fine too. Just light bulbs are easy, cheap and everyone knows how to use them.

You should be able to take it to the track and use it without a computer hooked up to it for those that don't have dischargers built into their chargers. Of course you wouldn't get data but at least you'd discharge your batteries.

The alternitive uses I was thinking about...

First... a way to test a ESC at high loads...

Second... A way to really deep cycle batteries... but that really is I belive what Hank's orginal intent for this device is.

Oh... third might simply be to get a really good idea about how much voltage drop you see on a perticular pack of batteries at some heavy amp load. Presumably the lower the actual IR of the battery, the higher the voltage should stay under heavy load.

Bascily... I'm really interested in this project Hank... I think it's got alot of potential uses for someone like me.

It could be programmed a lot of different ways. The basic setup will be a linear discharge. I'll make it fairly easy to change this. It will not have "external" adjustments, the program itself will need to be changed and then the microprocessor reprogrammed. That is easy to do and the code will be well documented.

I am doing it this way to keep the costs down while allowing fully adjustment. If we get into LCD displays and such it can drive the cost up quickly.

The nice thing about being able to reprogram the microprocessor is that once the hardware is done, it could be programmed to do a bunch of different things. Such as my previously "manually done" Oval Tests or even setup discharge profiles to vary the discharge rate during the discharge.

On the graph you can move your mouse pointer over any part of the graph to get the voltage/time reading at that point of the graph. You'll be able to share your raw discharge data with others so they can look at it in Excel or even in the graphing software (a free download).

Of course everything will be available on line, including the programming. Others that know how to program the Basic Stamp will be able to offer their own programs so that others can download them and try them out. Heck, hopefully they can even improve on my "stock" program... almost like an "open source" project where we all contribute.

It's turning out to be a cooler project then I first thought and there are a lot of possibilities. The hardest part is the signal timing for the ESC. The microprocessor can only do one thing at a time so we have to make sure that the ESC doesn't get "lost".

The ESC requires a "control" signal once every 10 to 15 ms. So I have to:
1) Send the ESC the control signal.
2) Check the amp draw and voltage then figure if the amp draw needs to be adjusted. Also check for the "cutoff" voltage and stop the progrom if the cutoff is reached.
3) Go back and send the ESC another control signal (within 10 to 15 ms of step 1) to keep the amp draw correct.
4) Send the data to the computer for graphing.
5) Go back to step 1 within 10 to 15 ms of step 3.

So we can see that the amp draw is adjusted about 50 times a second and data is sent to the computer about 50 times a second. Really, that is just too much data for most people's use and I most likely will reduce that to about 10 times per second. That is still 4000 data points for a battery with 400 seconds of run time. I guess if someone wants 40000 data points we can offer that too. That high data rate might be useful for tests.

Cool, sounds like a nice discharger. So, when do you think you'll be able to post some plans for the lap timer?? A simple design would work for now, as long as I could upgrade it.

At this point I have no idea on a lap timer. That most likely will be the next thing I'll work on.

I have been having the same thoughts. I was going to set up mine as a simple voltage regulator with the load determining the current draw. I set up a program flow chart. My only problem now is teaching myself how to program the PIC. During college, we learned how to program Zilog Z80s, and it was something I found interesting. According to a couple of people I have talked to, the modern PIC is quite nice to program.

I guess I will have to get reading again...

Phil

I am going through a small redesign in the discharger. I was using an 8 bit A/D converter (changes analog signal to a digital signal) but I don't feel the resolution on the readings are fine enough. I am going to a 12 bit A/D converter.

That will let me get down to .02 on the amp rate and .002 on the voltage. I didn't want to go with a 12 bit ADC as it is $5 more expensive then a 8 bit ADC but I think in the end the extra cost is work it.

Just wondering if what became of the Personal lap counter you were working on? Did you complete the project?

RC

My Brother and I worked on a lap counter that would speak each lap time to you through a pair of wireless head phones. It used a mini LED transmitter plugged into the car's receiver that sent a coded signal to a tripod mounted receiver beside the track. The receiver was plugged into a laptop that done the timming and produced the voice. The sound came out of the sound card into a wireless transmitter. My brother done the programming part and I done the electronic part. I quit racing and the project died.

With the introduction of the RC Data Recorder I decided not to go any futher on the project. A lap counting add-on should be the next item they develop for it.