How do I give a radio control car autonomous control

[Kenjones1935]

John,

My calculation for the amperage into the TYCO V23079 DPDT switch is 28mA at 5volts.

The spec says that the coil resistance is 178ohms. Isn't that close enough since this is not counting the output resistance of the PIC port.

Ken

[Kenjones1935]

In order to be able to draw an electronic schematic on this XP based computer downloaded the free version of McCAD Schematics Plus. It comes with a 279 page Adobe Reader Users Guide. I opened the McCAD window. It appears to be totally NOT intuitively obvious. Am I showing my age? Is there a better way?

Ken

[Kenjones1935]

John,

I want to see if I can send you a .jpg picture of my first scribbles with McCAD. I just uploaded McCADtest.jpg, Does it somehow get attached to this posting? From viewing the Preview apparently the answer is yes.

Ken

[John_Mac]

Hi Ken

Sorry to have not been very responsive. I had a mother board fail on my server and have been spending my time rebuilding the hardware and software...fun fun fun.

Yes I can read the schematic...

Do you have a digital camera? Sometimes a picture is worth....well you know the saying. I'm still trying to figure out the actual hardware we are dealing with. Don't need hi-res or anything. If you already have the RC Truck, can you tell me the make and model. I could try and look it up.

You might consider ordering some more PICs too, expecially if you are going to be running at or above max limits on the pin current for the relay. It might work fine, but you may not want to be down for a week if it doesn't.

On the ICSP and PICKIT2 programmer....think of this as the interface between your PC and the PIC. The PICKIT2 programmer lets you download the HEX files generated by your compiler, as well as set configuration flags etc. It will write and verify that the code was written correctly. That is a very simplified version, but may help. The ICSP feature is just that you can hook the PICKIT2 programmer to your proto board thru this 6 pin header that it plugs into. It lets you program the PIC in place on the board, rather than pulling the chip and putting it on the demo board. The PICKIT2 probably comes with the 6 wire ICSP cable. It will mate onto 0.1" spaced header pins that you can order online or find at Fry's or equivalent. The header wires go to various locations on the board. Some to the PIC itself. The PIC has programming pins that get activated by the programmer, and also power and ground. I will try to dig up a ref to how to wire it, but MicroChip should have it on their site and the pins will be defined in the Data Sheet (be sure to download this).

Hope this helps.

John

[Pic_User]

John,

My calculation for the amperage into the TYCO V23079 DPDT switch is 28mA at 5volts.

The spec says that the coil resistance is 178ohms. Isn't that close enough since this is not counting the output resistance of the PIC port.

Ken

Hi Guys,

Great project.

You could hang a transistor on the PIC’s relay driving pin. The transistor will “amplify” the pin’s current. This is the common tried and true way to drive much “heaver” relays. It is a good tool to learn and put into your tool box.
http://www.picbasic.co.uk/forum/show...17&postcount=6

A quick fix might be to drive the 28 mA relay with two PIC pins in parallel.

Either way, remember to use a suppression diode, directly on the relay coil, to drain any unwanted voltage spikes.

Keep Trucking,
-Adam-

[Kenjones1935]

Microchip says that my order is 2nd day Fedex. It should arrive either tomorrow (Monday) or Tuesday. Once it arrives I will begin to know where I stand.

Thanks Don for your pointer to the output circuits.

We don't have FRY'S in Massachusetts. We do have YDI (You Do It) but it is a long drive from Fitchburg. Other than Radio Shack what other stores will support me in this project?

My radio control car is not the one for the finished project. It is one I got for the correct price - free. It is a HPI Racing SPRINT 1/10 4WD Electric Touring. It is quite a beautiful little mechanism. It has two differentials. The four wheel drive makes in incovenient for the final vehicle. There is a drive belt the length of the chassis right where the PIC should go.

Electronicly it contains:
One radio receiver, one pretty hefty electronic speed control, one type 540 motor, one steering servo, one 7.2 volt Ni-Cd battery pack.

I had an idea for narrowing the lens angle for my light detector. I could put it at the end of a toilet paper cardboard tube which sticks out the windshield of the vehicle. A reasonably designed 360 degree turn might just allow the 'correct' light sensor to react accurately from, say, thirty to forty feet. What is the correct light sensor assuming I am using a 100 watt incandescent bulb.

Ken

[ScaleRobotics]

We don't have FRY'S in Massachusetts. We do have YDI (You Do It) but it is a long drive from Fitchburg. Other than Radio Shack what other stores will support me in this project?

There may be more surplus electronics stores around you, but I was able to find one that looks to be an hour away. http://smcelectronics.com/index.shtml

For mail order:
www.digikey.com
www.sparkfun.com
http://www.goldmine-elec.com/
www.halted.com


are nice. I notice that if I can't find it at the surplus stores, it is a LOT cheaper to get mail order than to get them at Radio Shack. Besides Radio Shack does not seem to stock half the parts they used to 5 or ten years ago.

[John_Mac]

I was able to find:

HPI Racing Sprint 2 Flux RTR w/Ford Mustang GT-R

Must be the same or similar. I looked at the specs and replacement parts and was able to find a picture of the ESC. Indeed it is a standard 3 wire servo cable config. So I assume the RX has the same 3 times 3 pin headers on it to plug the servo cables into it. This is good, cuz most (cheap) models have a custom control system to save cost and is next to impossible to figure out.

You said the RX has 3 channels but only uses 2. That's also good. You can use the 3rd channel for auto/manual detection.

The power to the RX is likely being provided by the servo cable from the ESC. The ground and power pins on the RX are on a bus. You only have to provide one channel to power all. So when you run the servo cable from the unused RX channel to the board, you will have 5 volts (check it) and ground available on the cable to power the board. This power should be fine in terms of conditioning. It is the raw main battery that is dirty.

Here are some sites to look at for parts... there are many more:

http://www.rentron.com/index.html
http://www.sparkfun.com/commerce/categories.php
http://www.parallax.com/
http://www.pololu.com/

Here is an overview of the ICSP I discussed.

http://www.embedinc.com/picprg/icsp.htm

Best,
John