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One thing you will need to do at the start is "global" scan to find the light to start with. It may or may not be in the limited forward acceptance of a detector array. So maybe a 360 azimuth array? or a forward and backward detector on the servo I described?
Kinda depends on the number of input channels are available for this specific function.
John
John,
My thought was that my light detector would be on the front of my car. The servo searching capability could be done by steering right and left just a little bit. This way the car goes directly to the light.
I imagine that once it gets there, the student operating he RC transmitter will be able to see it and retake control. These things go way fast under RC control. I image it creeps when autonomous.
Make sense to you?
I am having a difficult time figuring out what Basic Stamp starter kit is the best for me. I am USB oriented. I am guessing that I should spring for the 160 bucks for the BASIC Stamp Discovery Kit - Serial (With USB Adapter and Cable)
Your thoughts please. I'm going to bed now. It is eleven o'clock out east.
Ken
I figured that the very first thing the car would do once under autonomous control would be to make a 360 degree circle. Somewhere in that circle it would be facing the light bulb. That should do it.
Ken
Steering to find the source might not converge, but that is part of the fun so try it see what happens.
Dave recommended the PICKIT2 from MicroChip and buy PicBasic compiler. If you know C, you can download a free compiler from MicroChip. I had mentioned the pros and cons of starting with PIC or going to Basic Stamp (ready to go, free compiler, but expensive and one chip/project). Looks like you decided on Basic Stamp.
I would recommend the USB version of whatever you buy. Fewer computers, mostly laptops, have a real serial port.
As I said, I got limited by the number of variables and to some extent the code space on the Basic Stamp. It was a good learning platform, but I eventually went the PIC route, much more flexibility. If you stay in the game and get more complex, you will probably end up migrating to a PIC.
If you go Basic Stamp, USB Board of Education or similar is a good basic system.
You may want Dave to weigh in and see his thoughts.
There is no unique answer.
John
I am not up on the basic stamps (SX,propeller), been several years ago that I last played with them. Do they have ADC (Analog Digital Converter) now?
If you go with something like the 18F4550 you have 13 ADCs and it can run at 48Mhz with a 4Mhz external OSC.
Language --- C, ASM, a flavor of Basic??? Of course I am in favor of PBP. It is pretty much bullet proof and the support can not be beat.
How to make an algorithm for automation??? I suppose everyone has their methods but I will study how a human does the task (a large part of my work is automating existing machinery) and go from there. If I find something to make it all more efficient but not something that the humans are doing for whatever reason (360 viewing ?) I will consider a change in the procedure.
It will be interesting to see what the students come up with...
John and Dave,
I am more than willing to go with PICaxe. We have a MicroChip outlet here in middle Massachusetts close enough for me to enroll in a course or two.
https://secure.microchip.com/RTCV2/C...e.aspx?rtcid=5
I am comfortable with C. Many years ago I coded in Assembly. (Funny thing there. I read the Wikipedia definition of PIC. It talked about a Harvard architecture. This description reminded me of the AN/FSQ7 which did the SAGE Air Defense of the USA in the 1950's. That computer was made of vacuum tubes. It read radar data off drums. The PIC Accumulator and Register structures sound similar. That was my first programming job - Lincoln Laboratory)
Please help me select a PIC product kit that would get me started. I need to have that nudge to dig out my soldering iron and borrow an oscilloscope.
Ken
I have on my computer screen the 101 page PICaxe Manual1.
I don't think I have enough ink to print all 101 pages. I am too old to be comfortable with reading a whole manual on screen. Sigh...
Ken
No perfect solution....
PICAxe are MicrChip CPUs that have a bootloader installed so you don't need a programmer to program them. You can't buy any old PIC and make it work, but apparently there are PICAxe chips that look like PIC family. Also don't know their availability, nor cost. The nice thing is that the PICAxe kit comes with the power supply, proto board etc, much like the Basic Stamp which makes prototyping easy. Also looks like it works with MPLAB IDE (free) and the free MicroChip compilers.
To go with the standard PIC route (which is what I do), you will need a programmer like the PICKIT2 on the MicroChip site (not the dev kit, just tthe programmer and USB cable). Then you would need to build up a proto board. Many places sell these in various sizes as well as the jumper cables to hook up your project. You will need to provide a regulated +5 VDC to the board using something like a 7805 regulator and caps. You will need a 5 pin 0.1" header to connect the PICKIT2 programmer to the board to program the PIC. Buy a few PIC's, caps, resistors etc. You download the free MPLAB IDE and C compiler (or buy the PICBASIC compiler to use BASIC. This gets you to a point you can start wiring up a circuit and debug some code.
Unless you start making PCBs, you might keep your project on a proto board with all the components and get another proto board for the next project. Places like Radio Shack and Fry's Electronics sell these boards for a few bucks.
If you go to the MicroChip site, you can get a list of what chips have what capabilities. Might look at 8 bit processors. On of the chips I use is the 16F88. It has 7K of program space, 1 PWM/Capture hardware port, 7 channels of ADC, 3 timers, and 2 comparators. Plenty of capability to get started.
I have already discussed the Basic Stamp system.
So all depends on how much "ready to go" or "DIY" you want. I think people learn a lot more in the end with the DIY approach, but for people that are easily frustrated, not so good.
As you can see, I went the PIC route (although I used a different programmer).
So now you get to decide. Good luck.
John
John,
You suggested that I use a PICaxe kit that contains a power supply and a proto board etc.
Trouble is I have been trying to figure out which one that is.
Would you be willing to suggest a PICaxe kit model number.
Ken
Hmmmm
Don't think I recommended PICAxe...Dave wrote something on it. I just noted that you need special PICs.
Maybe you didn't read my last post.
I'm reluctant to recommend a specific approach, since it depends on what your really want to do. I tried to give the pros and cons of the various systems. For my own personal likes/needs, I went with the PIC route (not PICaxe) described in my last post.
Once you choose which approach you want to take, I can provide specifics.
Best,
John
not me.Quote:
Originally Posted by John_Mac
I say get a PIC and a PicKit2 and be done with it.
I never have used a picaxe and do not have any plans to.
Get the real thing and pick a language and get started!
My mistake Dave///not sure how PICaxe came up come to think of it.
Git er done!
I did it. I am not sure what I did, but it will get me started. In addition there is a local Radio Shack just a couple miles down the road.
The Microchip Store WEB page said:
DV164121 - PICkit 2 Debug Express
23-Nov-2009 25-Nov-2009 49.99 1
I will need more, but at least I will have something.
Ken
Did you order a PIC or two?
Dave and John,
I think the second item in this description of a Debug Express is a PIC16F887. Isn't that the micro that I need?
Features of PICkit 2 Debug Express:
* PICkit 2 Development Programmer/Debugger
* 44-pin demo board with PIC16F887 Midrange PIC microcontroller
The PIC16F887 may be debugged directly without any additional hardware.
* A series of 12 Lessons on assembly programming that cover I/O, A/D converters, timers, interrupts, and data tables (All source code files are provided)
* A Debugging Tutorial on using the PICkit 2 as a debugger with the MPLAB IDE (Ch. 4 of the PICkit 2 User’s Guide)
* Getting Started in C tutorial on developing and debugging in C with a FREE CCS PCM™ Midrange C Compiler Demo* for PIC16F887(contained on the PICkit 2 CD) *2kWord Program Limit.
* Getting Started in C tutorial on developing and debugging in C with a FREE HI-TECH PICC™ LITE C Compiler with MPLAB IDE
* FREE! Microchip’s MPLAB IDE software for a complete code development environment
----------------Yep. This should get me started--------------
This powerful yet easy-to-program (only 35 single word instructions) CMOS FLASH-based 8-bit microcontroller packs Microchip's powerful PIC® architecture into an 40- or 44-pin package.The PIC16F887 features 256 bytes of EEPROM data memory, self programming, an ICD, 2 Comparators, 14 channels of 10-bit Analog-to-Digital (A/D) converter, 1 capture/compare/PWM and 1 Enhanced capture/compare/PWM functions, a synchronous serial port that can be configured as either 3-wire Serial Peripheral Interface (SPI™) or the 2-wire Inter-Integrated Circuit (I²C™) bus and an Enhanced Universal Asynchronous Receiver Transmitter (EUSART). All of these features make it ideal for more advanced level A/D applications in automotive, industrial, appliances or consumer applications.
----------------------------------
I am going to need a power supply as I would rather the PIC not share the battery that drives the motor. It is a 7.2v and has plenty of work cut out for it just making the car go fast. Initially I think the PIC gets its power off the USB cord.
I am going to need some relays and some surge eating capacitors.
I am going to need to drive the relay.
I'll need hook up wire and a soldering iron and solder and whatever the modern proto kit uses.
I'll need a light sensor and a way to give it tunnel vision.
What else??
Ken
Ken
I'm not sure what the demo board really is that comes with the PICKIT2. If it has to be soldered, you may want to consider getting a proto or bread board to do your prototyping. This is a board with holes into which you can place jumper wires (which you can buy a box of different lengths already cut and bent) and make connections without soldering Typically, I need to mess around with the circuit to make it work or optimize it. Soldering and unsoldering really impacts my ability to try different things and make progress. I save soldering once the circuit has been fully debugged. Also, I would typically put a voltage regulator IC such as the 7805 to provide clean regulated power to the PIC on the proto board. I also use In Circuit Serial Programming (ICSP) using a 6 pin header that the PICKIT2 plugs right into to program the PIC. I don't want to have to pull the chip out every time to program it.
I usually break my project up into logical units and test individually. If you are going to control the throttle with the PIC, you could build a circuit to do this and the PWM code to control it. Same for steering, test out servo control with the kinds of inputs you expect. You may find that the PIC cannot actually drive a steering servo with its own power supply. You may have to provide the control signal from the PIC, but provide a separate power supply for the servo.
Same is true for the light seeking hardware and control software (which will be a bit challenging I think) and your manual/auto relay switching.
Only when all the pieces work, do I attempt to integrate. Even then, one at a time. Thus you can see the benefit of a proto board without soldering (at least for me).
You are also quite right to isolate the power for the motor from the electronic control supply. There are big spikes on it and would be very hard to clean up.
I found an oscilloscope extremely useful in debugging the PWM control circuit and hardware. You can learn a lot about the hardware and software if you can look at the signals.
You may know all this, and can just wire it up, program it and it will all work. If my approach is different than what you want to do, just say so and I will back away from the keyboard:)
Hope this helps
John
Professionally I did digital hardware design, prototype, build and ship. That ended in 1973. I was working for CODEX. At that time I was promoted to management. I was that long ago? OMG!
I did not like management. I stepped down after a few years (we had a parallel salary scale) and went into programming.
I am now retired. I have forgotten more than I ever learned. I probably would not recognize a modern oscilloscope. Maybe I should go to a flea market to get one made by TI. I haven't seen them yet on Antique Road Show. (A friend of mine in that business mentioned the other day that Heath Kit radios are rising in value.)
I have some design images in my mind for this RC/autonomous vehicle.
The modern acronyms are driving me up he wall. I need to get something in my hands soon!
Ken
I did not think that Texas Instruments sounded correct when I wrote that last post. They were, of course, Tektronics oscilloscopes that danced to my touch oh those many years ago.
Ken
I need acronym help.
I need to purchase an appropriate DPDT switch. I plan to use this to switch the BWM signal going into the Electronic Speed Control (the driver of the propelling wheels motor) from either the output of the radio control receiver or the output of the PIC.
Is this the correct set of specs for my proto? I need your judgment on the mounting method. I don't know what the PICkit dictates.
Signal Relay
NEWARK Electronics: Part #35K3233
TYCO ELECTRONICS V23079B1201B301
Coil Voltage VDC Nom:5V;
Coil Resistance:178ohm;
Number of Poles:2;
Contacts:DPDT;
Relay Mounting:PCB Surface Mount;
Carry Current:5A;
Coil Power VDC:140mW;
Leaded Process Compatible:Yes;
I'm headed over to our local Radio Shack. I am not impressed with the RS WEB page.
Ken
Ken
You should download the data sheet for your PIC from MicroChip website.
Typically the max current any one pin can drive is 25mA, 100mA total for a port.
So whatever relay you choose must stay below the 25mA level. That is what I told you a while back as a drawback to the relay approach. If you find that you are drawing too much current, you may have to wire up a transistor circuit that drives the current.
The PICKIT2 programmer wont care how you wire things up (other than how it talks to the PIC), but you will need to connect the PICKIT2 programmer to your PIC, through the 6 pin ICSP header I described earlier.
Are you going to use a separate proto or bread board as I mentioned???? Or the demo board that comes with it? I suggest the proto board if the demo board requires soldering (as I said before)
It is very difficult to comment on your questions without a lot more info. You might consider drawing a schematic or something so we are talking off the same page. Also need to know a lot more about what controls you RC truck has on it. Some pictures would help too. Is it a RX with (how many) channels, with standard 3 wire servo cables? Some of the RC trucks have custom electronics to save money.
If you have a standard setup with 3 wire servo cables, you need to switch the signal wire only (this has the PWM signal on it). The power (red typically) and ground (black typically) can be common to all the components. You will need a common ground for all this stuff.
Basically, I just don't have enough info to give you specific guidance at this point...but happy to do so if you provide some info.
Best,
John
John,
My RC hobby level car has one powerful motor and one servo. The motor drives both the front and the back tires. The servo positions the steering. The RC has three channels. One is not used.
I do not know how to draw a circuit diagram on a computer. What application do you use?
You mentioned a six pin ICSP header. I have no idea what that is. Wikipedia says, "Most PICs that Microchip currently sell feature ICSP (In Circuit ... special headers ". I can not picture that. I am acronym deprived.
I got an email from Microchip today telling me that my order has been shipped. I will wait for it to arrive then go to Radio Shack to see what they sell that looks like what I got. The man there seemed very helpful.
I plan to switch between the two PWM signal aimed at the ESC. Not the power to the motor.
I am concerned about the power because the radio receiver on my car gets its power from the 7.2volt battery via the ESC. I do not want to power the PIC from that source. A common ground is no problem.
You wrote:
"If you have a standard setup with 3 wire servo cables, you need to switch the signal wire only (this has the PWM signal on it). The power (red typically) and ground (black typically) can be common to all the components. You will need a common ground for all this stuff."
I do not want the power to be common to all components. I want the PIC to have its own supply. Yes, it is the white signal line into the ESC that i wish to switch, but that implies common power.
What application do you use to draw a circuit diagram?
Ken
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
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
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
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
Hi Guys,Quote:
Originally Posted by Kenjones1935
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-
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
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.shtmlQuote:
Originally Posted by Kenjones1935
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.
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
I understand that my receiver gets its power from the ESC which in turn is fed by the 7.2volt Ni-Cd battery. Do you all feel that powering the whole kit and caboodle from that one battery is OKAY? If that is the case many of my (imagined) problems are solved. Will the voltage regulator in the ESC withstand the added amperage? If it will then other potential problems disappear.
I still think I need two batteries. One to power the car. The other to power the microchip. The Ni-Cd runs dry after a few high speed runs of the car. It must be recharged. When used as I have been imagining by middle school students it will run down quickly. What happens to all the information in the PIC while I swap batteries?
Ken
I anxiously await the arrival of my PICkit.
Ken
The program memory in the PIC will stay there forever. Any variables will be reset a power up if they are not written to EEPROM. I do not think you will need to worry about that for this project, at least not to start with.
You suggested I check out:
http://www.picbasic.co.uk/forum/show...17&postcount=6
I see the reference to latching relays. I found at Newark only 12 volt and greater versions. My mental image of my car/truck carries a 7.2 volt Ni-Cd and a 6 volt AA battery pack. Do you know of an appropriate latching DPDT switch?
Ken
The ESC should work fine for both PIC and steering servo power. I would try it before loading up with separate battery packs. Typically the PIC will reset if you get a glitch on the power. You would see a short dead time while the PIC resets if this happens. You can also flash some LEDs in software on init if you want.
Just look at the ESC output on a scope and see how good/bad it is.
Hi Ken, John and Dave,Quote:
Originally Posted by Kenjones1935
I have seen some 5 V relays but it might be better to power a relay directly from your battery supply.
Then control it with the 5 V signal from the PIC digital pin.
You then, are not limited to the coil current of the PIC pin and more important, the electrical noise from the coil is outside the “inner sanctum” of the sensitive control circuit.
You would need an additional 20 cent transistor driver.
Here in the states these are some of the places that “mail order” electronic supplies.
These are full price electronic part distributors.
They generally have lots of choices and ship very quickly.:
Jameco Electronics http://www.jameco.com/
Mouser Electronics http://www.mouser.com/
Newark Electronics http://www.newark.com/
Digi-Key http://www.digikey.com/DigiHome.html
Allied Electronics http://www.alliedelec.com
These are surplus, few of a kind, less of a selection overstock type places.
Stock quantities are limited and they ship a little slower:
All Electronics Corp http://www.allelectronics.com/
Electronic Goldmine http://www.goldmine-elec.com/
BG Micro Electronics http://www.bgmicro.com/
Marlin P. Jones & Assoc., Inc. http://www.mpja.com/
Fair Radio Sales http://www.fairradio.com/
Hosfelt Electronics, Inc. http://www.hosfelt.com/
I buy most of my parts, to stock the parts bin, from eBay:
eBay Inc. http://www.ebay.com/
You guys are starting an interesting project for all the right reasons!
-Adam aka Pic User-
Hey Adam,
Do not be a stranger...
I think Ken could really benifit from your insight on a project like this.
You guys are pretty much on top of the whole “Getting Ken up and running with a PIC” mission.Quote:
Originally Posted by mackrackit
We should caution him and other “newbie PIC users”:
Start slow. Before diving into the atomic powered matter transporter project, blink a LED .
Then make a switch toggle a LED.
Baby step your way, to world dominance.
We are all reading this thread and pulling for Ken to continue with this excellent idea.
-Adam-
I looks so innocent - so small. It is difficult to imagine it can cause me so much frustration and consternation. Do I need to be careful with static electricity?
Happily I have located a dust covered oscilloscope which should arrive this week. Thanks for the support. It feels good!!!
Ken
Static electricity.
If you are not rubbing balloons on your head you are probably OK. :)
I just make sure to touch something that is earth grounded to discharge myself before working. I have NEVER used a wrist strap for any work.
But that is me.
Like Adam said, now it is time for blinkey.
Gang,
When my PICkit 2 arrived I wondered how I would learn this particular PIC's structure and programming. I do not like reading .pdf files on screen. I hate to use up all my ink printing hundred + page documentation.
Then I noticed ==> sitting open and forgotten on my desk "RUNNING SMALL MOTORS with PIC microcontrolllers" by Harprit Singh Sandhu.
A month ago I purchased this book from AMAZON.com. It was open to Chapter 3 entitled UNDERSTANDING THE MICROCHIP TECHNOLOGY PIC 16F8777A:
That's the PIC in my PICkit! Coincidence?
I'll probably shut up now for a while.... The kids are driving up from New York City. Have a great holiday.
Ken
Ken
I am having a difficult time with the forest of Microchip .pdf files.
Evidently my PICkit 2 Debug Express does not contain a compiler. I assume it contains an assembler, but I have found neither the specs for assembly language nor the assembler executable itself. Any suggestions?
What higher level language do you all suggest? Which version is the best. How much does it cost?
Ken