14 replies to this topic

[Stefan]

Hi Guys and Girls,

Currently I have a successful Netduino driver for this shield: Arduino Motor Shield (L298N).

The shield is quite simple; you can connect 2 DC-motors to it, and by sending some signals it's possible to change voltage to each motor from -12V to +12V (when Vin is set to 12V)

Now I got it to work on the Netduino I'm looking for a good solution to make it easy to control. I have four ways in mind, these codes do the same. Which one do you prefer?
The code sets motor one in reverse at full speed and the second motor half speed forward.

MotorShield.SetMotor1State(Directions.Backward, 100);
MotorShield.SetMotor2State(Directions.Forward, 50);

MotorShield.SetMotor1State(-100);
MotorShield.SetMotor2State(50);

MotorShield.SetState(Motors.Motor1, Directions.Backward, 100);
MotorShield.SetState(Motors.Motor2, Directions.Forward, 50);

MotorShield.SetState(Motors.Motor1, -100);
MotorShield.SetState(Motors.Motor2, 50);

I can also create an overload so all of the above will work, but that could be quite some overhead on code memory.

I made a poll and will work out the option with the most votes. The driver will be done this sunday, already got it 100% working.

[Michel Trahan]

Hi Guys and Girls,

Girls ? Where ?

Currently I have a successful Netduino driver for this shield: Arduino Motor Shield (L298N).

Cool, I'll want one when budget will allow I know it is a stupid question with you since you will ... but can you add it to the sandbox wiki ?

MotorShield.SetState(Motors.Motor1, Directions.Backward, 100);
MotorShield.SetState(Motors.Motor2, Directions.Forward, 50);

I vote for this one, you can easily read the purpose of the code

that could be quite some overhead on code memory.

I vote for not adding all those overloads ... no overlords please (pun intended)

[Stefan]

Girls ? Where ?

It was a subtle way to find that out!

I know it is a stupid question with you since you will ... but can you add it to the sandbox wiki ?

I will when it's done. I hate to put stuff online that isn't finished, but expect a nice article before monday!

I vote for this one, you can easily read the purpose of the code

True! The only thing I have against it is that an enumeration requires additional memory, but it's a very clean way.

I vote for not adding all those overloads ... no overlords please (pun intended)

I totally agree, although sometimes I'm happy overloads are possible!

[Mario Vernari]

Hi guys (at now, no girls at sight...at least from your pictures) I voted for the 4th option, because it is the most abstract. I think that the most exciting task in the motor control is the speed-shaping, that is *NOT* easy! Consider having a simple motor, where you may control its speed from -100 to +100%. Now imagine having a dish hardly connected to the motor axis. On the dish there is a sign (e.g. at 12 o'clock). The deal is: the motor/dish is idle with the sign exactly at noon. Let spin the dish N times as fast as possible, then position the sign back to noon. When your brain is melted, but you've got the goal, just add this puzzle: - grant the performance with dishes of different weight. LOVELY!!! Ciao

[Stefan]

The motor shield is intended for DC motors which aren't very precise. But it can be very useful for robots. You can let them walk slow or fast, forward and backward. If you want a precize motor it should be a servo anyway I suppose. There's a solution for every problem, this one isn't a solution for clocks but a very nice one for rc cars and stuff I suppose I liked the 4th myself as well, but I like the diversity in opinions in this. To be honest, I designed "MotorShield.SetState(Motors.Motor1, Directions.Backward, 100);" at first, since that's how the shield works; a pin that switches forward and backward and a pin that defines speed. But while giving it some thought I decided to do "MotorShield.SetState(Motors.Motor1, -100);". Then I though some more and was like: "what would others do and why?" And to get an answer on the first thing; Chris, if you read this, can you query how many users have their gender on female?

[Chris Walker]

There are definitely some ladies who frequent the forums. But they're vastly outnumbered by the gentlemen, so perhaps they don't speak up often (or don't disclose their gender). [ That said, ladies...you are welcome in this community. The guys are friendly. And if they aren't, just let me know ] Chris

[Stefan]

Nice said Chris, appairently two people totally agreed according to the button

[Hinnie]

The ability to simultaneously send two engines missing in the choice, therefore I can not participate in your poll

[Stefan]

The ability to simultaneously send two engines missing in the choice, therefore I can not participate in your poll

it's possible, it can drive two motors simultaniously.

[Mario Vernari]

The ability to simultaneously send two engines missing in the choice

It is preferable to keep a certain level of abstraction, instead of making a custom call for a bunch of users.
What if tomorrow there will be John Smith asking for three motors?

However, relating to high precision positioning, it would be nice if there is some way to keep in sync two o or more motors.
I think this is very far away, at the moment.
Cheers

[Stefan]

Ahhh like that. it's near to impossible to drive both motors simultaniously with exactly the same speed. DC-motors aren't precise and can't be trusted. But for just some speed (like netduino based vehicles) this is good enough.

[Stefan]

Ohh it's a tie between: MotorShield.SetState(Motors.Motor1, Directions.Backward, 100); (3 votes [50.00%]) MotorShield.SetState(Motors.Motor1, -100); (3 votes [50.00%]) hmmm appairently there are good reasons for me to doubt between those two options

[CW2]

MotorShield.SetState(Motors.Motor1, Directions.Backward, 100); (3 votes [50.00%])
MotorShield.SetState(Motors.Motor1, -100); (3 votes [50.00%])

I've just voted for the latter - the speed value can include the direction, positive - forward, negative - backward, zero - stop, so it is not necessary to have an extra 'direction' enum. I don't know what modes the used H-bridge supports, IMHO the reasonable use of enum would be to represent possible DC motor modes - running (left or right), coasting (free run) and braking (short circuit), because some of them (coasting, braking) do not have the additional speed parameter.

[Stefan]

Too bad, the shield only provides the feature to move forward and backward at different speeds.

[Stefan]

Driver is finished, you can download it here: MotorShieldDriver.zip

Going to make a wiki page this weekend.