PBP projects for R/C models

[ScaleRobotics]

Usually an H bridge is used for forward and reverse. It is pretty much what you describe, only using two more fets. Microchip has an application note about one here: http://ww1.microchip.com/downloads/e...tes/00893a.pdf . It shows a nice diagram of the different states of forward and reverse on page 3.

In your post, I don't understand the " It could steer the correct MOSFET signal with a third 'direction' output." part though.... Don't you steer with a servo?

[Kenjones1935]

When I wrote, "It could steer the correct MOSFET signal with a third 'direction' output."
I was thinking of simplifying the speed control functionality by separating out the FORWARD and BACKWARD aspect. HPWM can easily create a PWM signal between one and two millisec. A second digital HIGH and LOW could dictate rotation direction. I've seen reference to something like this, but I did not think it through.

Ken

[Kenjones1935]

I think I have the ESC nailed. I have a procedure for powering up that seems to give predictable robocar behavior.

Do you all have some creative ideas for things to do with this little car. Right now it follows a wall counter clockwise looking down at a leisurely pace. High speed introduces response time problems. Two sonar proximity sensors can be placed looking anywhere from the car and a pot controls the top forward speed the half forward speed.

I can show you all the code if you like. It is crude, but it works.

Ken

[mackrackit]

You say looking down. Do you also have it looking for drop offs? Along that line maybe something like a seeing eye dog/bot?

[Kenjones1935]

There is a new car out that parallel parks itself. My car could do that if I put one sonar on the back bumper.

It could also detect motion if it were standing still. A relay race? I just thought of that. I like it....

Ken

[Kenjones1935]

The model level car is too expensive for middle school use. It seems to be too fast for my level of software and SF05 sonar sensing. I have found a commercially available electronic speed control that has no 'smarts', but that's $50 added cost to the package.

The 1/10 size gives me more room under the plastic car body for my solderless protokit plus an extra 4 AA battery package. This $50 toy car comes with a 7.2 volt rechargeable battery. There is still a mystery. How can the PIC detect that the RC transmitter is turned on? Presently turning on the transmitter with the trigger in a particular position stops the car in its tracks, but does not toggle to RC control.

All this sounds soo good. But.... go look at



It is not good. This has been frustrating. You can hear the car spin its wheels on the cement floor. I've not been able to get it to follow the wall. It turns too far when making what should be small adjustments. Could be my code. I'll share it if you want.

On the plus side this car cost $50 retail. It is light and very robust - as you can see. All my solderless kit easily fit underneath the plastic shell with holes for the sonar sensors.

As of right now It does seem that the model level car with the POT to adjust the speed is the way to go.

Ken

[Ioannis]

Hi Ken.

I would like to ask, is the steering servos linear in control or just like ON-OFF switch?

I mean can you control the amount of turn, or the angle that the car will turn? Or is it full right, full left and center?

Also I cannot see if you really have speed control over the car. It seems that it accelerates fully in every direction.

Anyway, sure it is very nervous in reactions. I will repeat my self and tell you to have a look at PID control. It is the only way to have smooth control of the speed and steering.

Ioannis

[ScaleRobotics]

Yes, these are the same devices. 0.1" on the spacing. They are made for breadboards. More about them here:
http://www.schmalzhaus.com/UBW32/

[ScaleRobotics]

EMCelectronica's price is ok, but their shipping really gets you. The CPUStick is 49 Euros, but shipping is 52 Euros ... ouch! Of course, it could be their store is set up wrong, and shipping wouldn't really be that expensive.

Here is one that fits your breadboard better than the other Sparkfun device:
http://www.sparkfun.com/commerce/pro...oducts_id=8971

I have trouble with some 44 pin devices, so I am a little scared of soldering one of these big guys. I would use an off the shelf product for testing, then if it looks like it would do the job, you could have some boards made and try some soldering.

[Kenjones1935]

Thanks for the tip. The board looks OKAY, but only if I can solder pins into those holes and plug the thing into a solderless proto board. Of course some of the pins across the bottom would not have matching holes.

Oh, I see. The picture of the red board in your "http://www.sparkfun.com/commerce/pro...oducts_id=8971" is the same as the picture of the green board in my previous posting. True? Do you think? The price there is OKAY if shipping is reasonable.

Ken

[mackrackit]

There is a link on Sparkfun's web site going here
http://www.schmalzhaus.com/UBW32/

[Kenjones1935]

What else do I need? I am confused but very impressed by the young man in the video. I'll get the ZIGflea later.

Ken

[ScaleRobotics]

What else do I need? I am confused but very impressed by the young man in the video. I'll get the ZIGflea later.

Yes, me too!

That should be all you need. However, this one does not come with StickOS installed. But you can use your PicKit2 to install StickOS firmware into it. And, by doing that, you will get the latest 1.80 version. You will need to download a windows driver from this page CPUStick.inf : http://www.cpustick.com/downloads.htm

But with that, and hyper terminal, you can start writing some code. Oh, and you won't get a manual either, so you will have to print one.

Walter

[Ioannis]

Hi Ken. I do not see why you should leave PBP and start another similar language and your project all over again.

If you do need RF communication between nodes maybe a Zigbee modules or RF transceivers can give you a good solution without almost a line of code.

Look at Digi modules (Zigbee or not, does not matter) for out of he box communication. Other brands also exist, many I can say.

Ioannis

[rtestardi]

Hi,

However, this one does not come with StickOS installed. But you can use your PicKit2 to install StickOS firmware into it. And, by doing that, you will get the latest 1.80 version. You will need to download a windows driver from this page CPUStick.inf : http://www.cpustick.com/downloads.htm

But with that, and hyper terminal, you can start writing some code. Oh, and you won't get a manual either, so you will have to print one.

Walter

I just stumbled onto this thread...

I'd like to also point out you don't actually need a PicKit2 to program the UBW32, since it comes with the Microchip HID bootloader installed -- you can just download StickOS to the board using the procedure here: http://www.schmalzhaus.com/UBW32/doc...mentation.html

Be sure to use the proper version of StickOS for the UBW32: http://www.cpustick.com/downloads/St...v1.80c.elf.hex

I'm definitely game to help folks get this into a classroom setting -- let me know if I can help. (Just drop me an e-mail; unfortunately I'll be out of town for a week starting tomorrow morning.)

One small comment on an earlier post -- if you are using pins rd0-rd4 on the PIC32 and configuring them for PWM/servo mode, then they are controlled in hardware without CPU assistance -- so the BASIC program can do any other things while they are generating pulses, without affecting the pulses.

-- Rich
[email protected]

[ScaleRobotics]

Not a problem Ken, this is definitely the hardest part. And the manual doesn't really pull it all together for me either. Once you have a connection, you almost don't have to worry about those parts again though.

Here is the hex file you need. I have it in a zip file attached. It also has the driver you need. You must install the driver into your computer. Right click the driver, and select install. Then hopefully when you plug the USB cord from the UBW to the computer, you hopefully will see something happen.

We will get it going, or die trying. Hopefully the former.

[Kenjones1935]

Thank you scalerobotics!

The .hex file you sent compares exactly to the one I used. At least each displayed using 'notepad' are identical. The .inf file you sent enticed WINDOWS XP PRO into displaying a GUI warning me against installing it as it had not passed the WINDOWS LOGO test! Do you think I should ignore the warning?

Ken