Tronic's AMC motor motion-controller with pwm/servo output

Yes of course - I totally forgot. That is one of the biggest advantages of your interface having the control loop in HW. I was too much into my own implementation using X-sim.

Hi to all,

I think that this post is a little off-topic but since I mentioned this here before...

Yesterday I took part on the recording of the episode of a TV show on the Greek National Network ET1 (also known as ERT) to present my robotics page (http://www.Greekbotics.gr) along with the other two moderators. We presented some of our robots with me presenting a walking robot. Except from the robots and they also asked me to say a few words about my joyrider simulator!


The show is called PSIFIAKI ELLADA (translated: Digital Greece) and from a litlle research, I did to see what they presented on their previous episodes, I found that their guests was famous greek people from entertaintment, political or academic set, that mostly presented the internet and technologies around it. So its a very serious TV show addressed to serious people. I must admit the fact that it did made me a little nervous.

The ET1 channel can be seen via satellite all around the world if you like to watch it. The episode that i took part will be transmited on Monday 26-11-2007 and time 17:00 GMT - 18:00 GMT in (starts 19:00 on my country that is in timezome GMT +02:00).

Its a one-hour episode and I'm propably going to appear after the first half of the show since there are other guests before me. So be patience in start. One thing that worries me is that I haven't given much time to enter to details about my simulator, atleast they said will show a video of it!

Regards, Thanos

CONGRATS THANOS!!! good for you you got your simulator on TV .

Keep up the good work...

Good work indeed! :top: Is there a way to see this for us that do not have that TV channel?

I'll have a friend to tape this and as soon as I have it in digital format I'll post the piece that shows my part and a link to it.

I have a few good news on the avr controller too, I'll post them right after...

Thanos

I've finished building my PCB board for the AVR motion controller down to the last detail of it! I tried the onboard ponyprog programmer and it works fine! I was able to set the fuses of an virgin Atmega8535 to be able to use the 24Mhz clock and then I succesfully programmed it with a hex firmware that I had given before. During the programming procedure the RED Prog LED was flashing as expected. For quick verification that it worked ok I hooked up an LCD screen on it. Of course to program it with ponyprog, I had to remove the three green jumpers that are side to the blue jumper switches (I left them on on the photo) and place four wires between the two black headers (MOSI to MOSI, MISO to MISO, SCK to SCK and Reset to Reset). I need to make some connection diagrams and include them in the ponyprog guide anyway...












Now on the small paralled lcd PCB stuff: You may noticed the double row of the 16 pin headers and wondered why I designed this way... Before years I was invented a cool way to hook the normal LCD pins of an 2x16 LCD screen to the small backpack LCD PCBs I designed without need of sodlering it. You can see that I used longer 90 degrees pin headers with straighten sides on the LCD. On The LCD PCB board I placed short pin headers. So to connect the LCD you only need pass thru the remaining holes the LCD and use some jumpers to keep it in place.











And I had to also make a molex headers cable to connect the LCD. Making it is easy: Just cut eight wires, all with same length, strip 2mm on each side of the wires and with a help of a plier, you clamp the wire into the small metallics parts of the molex connector. No need to solder at all as the connection is strong. I used wires that are one-ply and are more rigid.





After soldered all the parts I noticed that the remains of the solder paste (Flux) I used to create perfect solderings, started to corrode the PCB surface in some places. So I had to wash the solder side of the PCB with Flux-off liquid and rub it with the help of an old toothbrush. Of course this alone doesn't eliminate the possibility of corrosion due to the contact with air so I also sprayed it with a thin plastic layer (plastik spray). Generaly Its better to start the soldering procedure and finish it in less than 2-3 days to clean it and shield it with plastik as soon is possible. If for some reason you can't keep up, you can place the PCB in gelatin film to keep it way from airs oxygen.






Regards, Thanos

Hmpf, Conrad wants to have 18Euros for the molex connectors^^
Thats far more than all other parts together^^

Honestly, I didin't pay more than 3 euro for all molex connectors (male and female) in the local electronics shop in Greece. In fact I could find all parts in very low prices than anywhere in internet...

I made the nessasary changes in the PCB of my AVR motion controller and I present you the next version:
AVR motion controller v1.4

The biggest fix in this version is that I increased the size of pin header holes, as I found the one in the v1.3, small and was tough to pass thru the pins.

AVRmotionsimulatorcontroller1_4.pdf (508.76 KB)

AVRcontroller_project1_4.zip (287.78 KB)




And I added a diagram to the Ponyprog guide to see the connection you need to do on the pcb to program the firmware on it.


Thanos_ponyprog_guide1_1.pdf (500.13 KB)


Regards, Thanos

Fixed the pots connections on Yobuddy's schematic:



I'll make one for RN-VN2 soon and possibly for other motor controllers too.

Also updated a little the first page of this post with new info.

Thanos

I made a schematic with wirings for two RN-VN2 controllers to support 4 motors...




More will follow...

Thanos

edited... :mug1:

Here is the part of the show that I appear. Too bad the showed very little part from my simulator videos... but I guess we are called to the show to present robots after all...

Greekbotics members, Guests on Psifiaki Ellada
http://www.youtube.com/watch?v=QTaEhrT_dVE


Thanos

Yes, its a pity that they havent shown more of your vids.

Maybe next time :gut:

One more

The red LED flashed. Programming was successfully :gut:

Looks nice. What did you used in place of molex connectors?

Thanos

I want to mention a function about the feedback potetiometers that is very handy in same cases.
I didn't wanted to show you this function before, since I wanted to verificate its working ok first.

On the AVR motion controller board there is a 10k multiturn potetiometer that its function is to limit the upper voltage level sended to the ACD comparison circuits of the Atmega8535. This means that you can scale down the usable reading range of the ADC. So you can reach the max (1024 value) by turning less the potentiometer.

Such scale down can be usefull in multiturn pots that we want to perform less turns than they provide. Thus you can convert a 10turns potetiometer to a 7turn or 5turns or even a 1turn if you like!

But the most usefull application to me is that you can convert the conventional 270 degree potetiometers to a 90 degree pots!!!!! I use 90 degree pots on my joyrider sim and lots of people asking where I got them. So instead of hacking toy RC receivers they can now use normal 270 degree potetiometers and limit their travel to 90degree by scalling down the ADC trim pot on the avr motion controller!!!








To be able to calibrate yourself the max travel of your pots I compiled a firmware that displays the ADC values of the 4 feedback pots on the LCD. Except of that you can use this to calibrate them on their actual position on your simulator to ensure that they don't go over the normal values. You should set them in such way that they provide values from 0 to 1023 for the full travel of motion of your sim.

POT_CALIB_HEX.zip (1.61 KB)


To visualise how this scale down of the ADC affecting the pots trave see the below graph (sort-of).



In every case, the scale down will affect the positive leg of the pot, meaning the 0 value will start normally from the physical start of the Ground leg.


Here is the way to convert a 270degree pot to a 90degree pot by using some math:

Since the ADC has 10bit resolution it will show 0 - 1023 points for any potentiometer, so in a 270degree pot:
1023 points / 270 degrees = 3.788 points per degree
Now if we multiply the step for the degrees we need:
90 degrees * 3.788 points = 340 points

So to limit the max travel of a 270degree pot to 90 degrees, we turn the potentiometer until it shows the value 340. Then we turn counter-clockwise the ADC scale down potentiometer (that will slowly rising the value) until it reaches the 1023 value!!! Thats it, you now have a 90 degree potentiometer!!


One thing you might forget it that my controller doesn't need end stop switches for the motors as it will never reach the end stops!! As long the potetiometers provide correct feedback for the position they will stay within limits no matter position command is received by the computer. If communication with the computer is lost, i.e. the game was crashed, the avr motion controller will maintain the last position commanded.


Regards, Thanos

@Thanos

I have been thinking about the function of this pot already.
Nice feature!

Btw, for what are the 4 molex cons with 3 pins for?

Another nasty thing: For Simforce sims the max difference between the actuator positions has to be adjustable.
If not, the frame could destroy the control rods.

I used the cheap pin-bridges in this version

The four 3 pin molex headers connect the max232 circuit to the microcontroller.

For now we need only to connect a cable between the two 3-pin headers named as RX.

This will enable the receiving of the serial data thru the I/O data input serial port.

I connected it as seen in the following photo:




The other two TX headers are there for future use to send back in the computer info about the position of the motors or the rest potetiometer inputs for fine tuning during play.

For Simforce sims, the max difference between the actuator positions will be adjustable by fine tunning it with a potetiometer from the rest unused pot ports.

Thanos