[chbot] Sensor Information

[Jim Ronald]

Hanno and Charles,

Thank you for your replies.  I'm not really looking forward to rolling my 
own H bridge. I'd rather use something like the "Dual VNH2SP30 Motor Driver 
Carrier MD03A" http://www.pololu.com/catalog/product/708 but I'm not sure if 
3.3V will be enough voltage on the inputs.  The datasheet says TTL and CMOS 
compatible but it also says, Input High Level Voltage min is 3.25V. 
Obviously, 3.3 is greater than 3.25 but 50 millivolts seems a little close 
to work reliably ( I'm not an EE so... ).

I'm also considering the "L298 motor driver kit" 
http://www.solarbotics.com/products/k_cmd/ which seems to be the best fit 
for my needs.  However, I sure it's very inefficient compared to the newer 
sexier motor drivers and I like the idea of being able to easily sense the 
motors current draw.

If I design my own board I will probably use the MC33887 motor driver.  And 
use a diode and resister to offset the 3.3 volts to 4volts for the motor 
driver inputs.  It may also be possible to modify the Dual MC33887 motor 
driver carrier
http://www.pololu.com/catalog/product/712 in the same way.

Thanks
Jim

----- Original Message ----- 
From: "Charles Manning" <manningc2 at actrix.gen.nz>
To: <chchrobotics at lists.linuxnut.co.nz>
Sent: Monday, March 23, 2009 10:44 PM
Subject: Re: [chbot] Sensor Information


> Hi Jim
>
> Have you considered rolling your own H bridge? Not too difficult. I can 
> show
> you a simple but reasonably efficient circuit if you wish.
>
> I have bought ICs from pololu.com who have been very responsive:
> http://www.pololu.com/catalog/category/17
> They also have boards:
> http://www.pololu.com/catalog/category/11
>
> What ever you do, avoid the L293D (not that it has enough power for the 
> motor
> you're driving).
>
> -- CHarles
>
>
> On Friday 20 March 2009 14:33:05 Jim Ronald wrote:
>> Hanno,
>>
>> I'm looking to drive a couple of GHM-01 motors using differential 
>> steering.
>> Which parts did you end up using for a motor controller?
>>
>> Jim Ronald
>>
>> > Hi,
>> > Thanks everyone for another great night at Kiwibots.
>> > I enjoyed the robot presentations and look forward to a line-following
>> > competition at the next meeting.  Richard, please share your plans for 
>> > a
>> > simple, low-cost follower so we can all build one.  Should we run two
>> > races?  One on a simple oval- say 1M in diameter, and another on
>> > Richard's more complicated shape?
>> >
>> > I enjoyed all the thoughtful questions about my DanceBot, ViewPort and
>> > the sensors I use.  Here are the part numbers:
>> > - Parallax Propeller on a Parallax Protoboard
>> > - ViewPort v3.0: earlier version available here:
>> > http://mydancebot.com/viewport
>> > - Lynxmotion Geared Motor (GHM-01) with Quadrature Encoder (QME-01)
>> > - ADC: MCP3208
>> > - DAC: sigma-delta resistor/capacitor using the Propeller counter
>> > - Temperature Sensor: npn transistor: bc109
>> > - Parallax PING sensor
>> > - Parallax Compass: HM55B
>> > - Hobby RC Gyro: GWS-PG03
>> >
>> > I'm happy to answer any questions.
>> > Hanno
>> > http://mydancebot.com
>>
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>
>
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