differently. 127 is full on in one direction and -128 is full on in the
other.
DLC
Shaggy wrote:
>Does the oDCMotor2 pulse work differently at 127 (full forward) than it does
>at EVERY other value?
>
>The thing that has me really baffled about this is why I am not seeing any
>kind of linnear degradation of operation. While the problem could be could
>be power draw, or it could be pulse frequency, I don't have any workable
>explanation why I get a steadily ramping up of activity up to 126, then
>suddenly full speed ahead at 127. The lack of activity below 127 (the
>ramping up is nothing to chirping to vibrating the tracks, they never
>actually turn) all looks like it could be caused by a variety of issues, but
>why do those issues go away at 127? What is different about that setting as
>compared to the others. Looking at the voltage on the lines doesn't show
>anything different at 126 vs 127, which is understandable since a smooth
>curve would make those two nearly identical.
>
>Does a setting of 127 on the oDCMotor2 behave in a different fashion than
>all other settings? Is full speed ahead special in some way as far as pulse
>frequency, or current?
>
>
>rtstofer wrote:
>
>
>>The oDCMotor2 uses the oPWMH to create the pulses and the oPWMH object
>>defaults to 19.6 kHz. This is because the PWM.period is set to 254 or
>>(20 MHz / 4 / 254 = 19,685) and the .prescale is set to 0.
>>
>>Unless you look specifically at the old oPWM object, the new
>>documentation doesn't tell you that you can control the prescale and
>>period properties.
>>
>>PreScale = 0 -> 5 MHz base frequency
>>PreScale = 1 -> 5 MHz / 4 base frequency
>>PreScale = 2 -> 5 MHz / 16 base frequency
>>
>>Period = 1..255 -> PWM frequency = base frequency / period
>>
>>This works with V6:
>>
>>Dim m as oPWM 'NOT oPWMH
>>
>>sub main()
>>
>>m.PreScale = 2 ' divide by 16
>>m.Period = 255 ' divide by 255 (256?)
>>m.DutyCycle = 127 ' 50% duty cycle
>>m.IOLine = 18 ' or IOLine = 17
>>m.Operate = 1 ' fire it up
>>
>>end sub
>>
>>End result is a 50% duty cycle at about 1 kHz.
>>Does the H-Bridge still work with the original motor?
>>
>>Post a link to the new H-Bridge so we can look at it before you buy.
>>
>>I think you will be better off to dump the oDCMotor2 object (and/or
>>the oPWMH object) and just use the oPWM object. This will allow you
>>to get a low frequency and the driver may work better. Of course,
>>you will have to control the two signal lines separately to get
>>forward/reverse/brake. Unfortunately, it will be audible as the motor
>>runs at very low speed.
>>
>>I don't know why the .prescale and .period properties were dropped
>>from oDCMotor2 and oPWMH but it can certainly cause a problem.
>>
>>Richard
>>
>>
>>
>>
>>--- In oopic@yahoogroups.com, Shaggy <charrington@...> wrote:
>>
>>
>>>Off the top of my head, I don't know. However, I would expect that
>>>
>>>
>>would not
>>
>>
>>>be an issue since the LCHB is sold by RogueRobotics to go with their
>>>
>>>
>>OOPic
>>
>>
>>>board. I would not expect them to be including the LCHB if it won't work
>>>with the board they are using. I believe it was working as expected
>>>
>>>
>>when I
>>
>>
>>>had it attached to the ATS motors, which are smaller than the Robotics
>>>Connection motors I am currently using.
>>>
>>>I'm leaning towards too much power draw. I'll try to look at that this
>>>evening. The motors can certainly draw too much power for the LCHB,
>>>
>>>
>>so it is
>>
>>
>>>looking like I will have to replace that, regardless of whether that
>>>
>>>
>>is my
>>
>>
>>>specific problem. After all, the 754410 is getting a bit warm, even
>>>
>>>
>>with a
>>
>>
>>>heat sink, when I run the motors for 10s.
>>>
>>>Therefore, if anybody has a recommendation, I'll take a look at it.
>>>Otherwise I might just go with the H-Bridge sold by the same company
>>>
>>>
>>that
>>
>>
>>>sold me the chassis and motors. I'm pretty sure that one will take
>>>
>>>
>>enough
>>
>>
>>>power, though I will still have to look it over some.
>>>
>>>
>>
>>
>>
>>
>
>
>
--
------------------------------------------------------
Dennis Clark ooPIC Tech Support
www.oopic.com
------------------------------------------------------
[Non-text portions of this message have been removed]
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/oopic/
<*> Your email settings:
Individual Email | Traditional
<*> To change settings online go to:
http://groups.yahoo.com/group/oopic/join
(Yahoo! ID required)
<*> To change settings via email:
mailto:oopic-digest@yahoogroups.com
mailto:oopic-fullfeatured@yahoogroups.com
<*> To unsubscribe from this group, send an email to:
oopic-unsubscribe@yahoogroups.com
<*> Your use of Yahoo! Groups is subject to:
No comments:
Post a Comment