New build, arduino, motomonster, 2dof

Coming along. Have boxes for the Arduino, Motor Monster and Raspberry Pi B+ which will run version 1.0 of this thing. Using a 12v case fan and a chunk of an old mac heat sink to cool the Motor Monster, a 12v -> 5v USB car adapter to power the RasPi which will in turn power the Arduino. Slowly but surely.

Sorry, I surely missed something. What will you use Raspberry Pi for? Apart from powering the Arduino

The RaspPi will power the Ardunio, program the Arduino, allow serial communication with the Arduino for motor control as well as provide WiFi connectivity potentially a web interface, etc. As @noorbeast mentions version 1.0 of this rig won't run SimTools but a combination of custom Arduino and Python code.

Wiring complete, fired it up with some test code and thankfully no mistakes -- though one pot is taking a beating I think

Appears both pots are doing a little jiggle.....I would investigate that a little further.

You can also try connecting the motors with a shaft, the thing like @noorbeast did, this could help in preventing motors bend and jiggle.



DX Racer - Compact Simulator

Barg, I think I blew a channel on my Motor Monster, I was changing some code and one motor just stopped, upon the second try I thought I heard a pop now that channel of the Motor Monster doesn't seem to function.

At first the direction indicator lights were both on, but having removed the heat sink and checking for damage (which there doesn't seem to be any on any components aside from the "something's burnt" smell) that channel still doesn't work, and the direction lights are off. Don't these things have protection?

o boy, "that" smell is Never a good thing.

smell = blown

Why are you changing some code? If you change the code you have to change the wiring as well. Did you run into any problems?

Not changing any of the wiring code, I'm writing my own controller code for the Arduino, I was working on some acceleration/deceleration code not sure why it would've blown anything I guess it can't handle 255 PWM with my setup as that's the maximum it would ever receive.

What would cause this and how do I prevent it from happening again?

I am not a programmer, but there exist 3 very good and working codes, so why you write an other code... The code of @RufusDufus (SMC3) has some security routines included, which (should) prevent the motors from any damage if something goes very wrong...

I won't be using this code with SimTools to start, plus I would like to understand from the ground up how everything is working. How is one suppose to know the upper limits unless they're tested? I'll impose a lower max PWM now, but still don't know what the actual max is or what it would've blown in this instance.

So let me ask this, what's the max PWM the Monster Motor can handle with these crab pot motors using ultrasonic PWM code?

I see @RufusDufus code has 100 as a limit,

int PWMmax1 = 100;
int PWMmax2 = 100;
int PWMmax3 = 100;

Is that generally what folks are using as an upped limit? I really don't want to burn another MM.

Ultrasonic PWM code I wrote should not interfere with any other PWM consideration...
http://www.xsimulator.net/community/marketplace/ultrasonic-pwm-with-arduino.102/

There is probably another reason to blown Hbridge...

Hi substatica,

Those settings in the SMC3 code are just the default values for first time use. They can be changed using the Windows SMC3 Utils setup program and the new values are stored in EEPROM and used from there.

The PWM sets the duty cycle, 100% (255 if you are using 8bit PWM) means that the H-Bridge is permanently on. In other words the Power Supply remains connected directly to the motor until the PWM changes.

Whether the H-Bridge can support a continuous 100% duty cycle or not depends largely on whether the current drawn from the motor in this state is within the H-Bridge limits.

In reality though as it is a max PWM value, for motion sims using PID feedback, the output wouldn't normally remain in this state for long - only ms at a time.

100% duty cycle should only be necessary to get the motors moving then it would typically drop and be very dynamic.

Make sure the H-Bridge has good cooling, it is usually overheating due to excessive current that causes them to fail.

The H-Bridge, the Monster Motor Shield from Sparkfun in this case, has thermal paste, a large heat sink across both chips and a PC case fan on the enclosure (pictured below). I was working on some code to accelerate (raise the PWM) when beginning a travel and decelerate back down when approaching the target, something was off and I suspect the motor got 255 PWM for potentially a couple of seconds. When I get a new H-Bridge I'm going to set a hard PWM limit to 100 I think.

The power supply is a converted HP server which many folks seem to use.

are you sure there is no possible short circuit?