Another question about wiring the Wheel kit /motor controller from parallax ?

LD

········ I have the HB25 motor controllers with the motor mount Wheel Kit using a Board of education Bs2.
·I have the 12v power wiring figured out but i'm having problems understanding the wiring for the position controllers to the motor cotrollers to the board of education. lcd cable from servo port on boe to motor controller 1 then jumped to motor controller 2. How does the position controller·and the motor controller get connected together??? Any help would be appreciated.·

W9GFO

I didn't know that the position controllers connected directly to the HB-25s. Neat feature.

From page 11 of the motor mount manual;

Parallax said...
The Position Controller is designed to be interfaced with an HB-25 motor controller to control the position
and speed of the motor and wheel. This can be accomplished by connecting a standard three-pin cable
from the header pins marked “To HB25” to the three-pin header on the HB-25. Be sure to connect each
end of the cable in the proper orientation of white “W”, red “R”, and black “B” as marked on both the
Position Controller and the HB-25. Connect the power leads on the HB-25 as usual (positive supply to
the “+” and ground to the “—&#8221[noparse];)[/noparse].

Rich H

LD

O.K. I have done this. but then the Parallax Instructions show the Setup for mode two to be: Servo cable Pluged into Microcontroller then to controller 1 Then into controller 2. Do I just ignore this? I don't want to Burn up any of my Motor controllers or the Position controllers.

W9GFO

My guess is that when using the position controllers with the HB-25s is that each position controller is connected to a HB-25 and each position controller is connected to a pin on the MCU. Mode 2 where two HB-25s are driven off one pin, does not apply in this situation.

Remember that was a guess - I really ought to read the manual before spouting off like that. Fair chance that I am not right.

Rich H

Searider

There are two seperate logical communications links and three seperate physical communications links.
First is the link from your MCU to the position controllers. Your MCU needs to be able to give instructions to both possition controllers and must have a communciations path to them. To simplify the wiring and reduce the number of output pins needed, Parallax allows you to daisy chain the two Possition controllers. You do this by logically using an address (set with dip switches) to uniquely identify the two controllers. Physically, you run a cable from your MCU to the first (does not matter which if physically first) Possition controller and then a second cable is run from the first to the second. There are many ways you could wire this but Parallax has made using this technique easy, simple and it uses standard Servo cables.

The secondon communication link is the link between the position controller and the HB25. The HB25 does the heavy lifting by controlling the high current lines to the motors while the Possition controllers directly controll the HB25. There is one HB25 for each Position Controller so this makes for two physical connections (one for the left wheel and one for the right wheel).

To recap, your MCU tells the possition controller what you would like to have happen in a rather high level way (go straight forward 200 units)
The Possition controller uses that to provide the HB25 with a low level signal (PWM) to cause the high level instruction to be executed. This of course relies on the feedback of the opto quadrature encoader on the Possition controller board.

I hope this helps.

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Searider

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LD

Thanks Searider and w9gfo. I think I have it Now. Will find out soon when program is in.

Searider

Let us know how it goes LD

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Searider

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LD

Well, the Connections are made, I've loaded the test position controller test interface.bs2 and I,ve tried the HB25 motor test.bs2. When I hit my power switch for the motors they sit idle for a short time and then they start rotating clockwise then counterclockwise. One may be going in one direction and the other goes the opposite way but then they change direction sometimes going the same way other times opposit directions .Just like it is looking for a starting point. Also I've noticed that they are adding 1 revolution each time they change direction. Has anybody had simular things going on? I,m trying to think this thru but confused right now.