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Author Topic: $50 Robot Servos Stuck at Zero  (Read 1537 times)

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Offline BinarySlaveTopic starter

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$50 Robot Servos Stuck at Zero
« on: November 25, 2009, 11:51:48 AM »
Hello,
I'm a newbie trying to build the $50 robot following the tutorial.   I've gotten to the point of sending the Photovore_v1.hex through the AVR Studio [Program] button.  Everything works without error, but the code is behaving as if it still has the hold_servo.hex loaded.  When powered on, the servos spin slightly and lock in that position while I thought they would continue spinning.

Everything is identical to the tutorial, with the exception of the sensors.  The plan was to go straight to the Sharp IR sensors, so I didn't connect any photoresistors or sensors at all.  I thought the servos would just spin in the absence of photoresistors and it looks to me like the code would cooperate in the absence of values in the sensor_left/sensor_right variables.

I've literally tried everything a clueless individual can come up with.  Unfortunately I can't get the step-through option to work (I'm using Admin's makefile unmodified and the –g$(DEBUG) is in place) so I'm really lost on what is happening.  If I erase the flash memory through the [AVR]; Program tab; [Erase Device], the wheels "unlock" as I would expect.  But as soon as I upload Photovore_v1.hex, the servos spin slightly and then stop in a "locked".

Bad part is, I didn't even order photoresistor/1.5 ohm resisters. If there were any point to going ahead and connecting an IR Sensor, I'd chance it but my hope was to make sure everything else was working first.

Does anyone thoughts on why my servos won't spin continuously?

Thanks.

Offline Soeren

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Re: $50 Robot Servos Stuck at Zero
« Reply #1 on: November 25, 2009, 02:48:01 PM »
Hi,

Did you modify the servos fully?
It sounds like the potentiometer is still mounted and moves with the servo shaft (if they move less than 180°).
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline BinarySlaveTopic starter

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Re: $50 Robot Servos Stuck at Zero
« Reply #2 on: November 25, 2009, 03:54:44 PM »
Actually, I messed up the first servo and ended up buying the 180° (ServoCity).  I just double checked by turning the servo clockwise until it stopped, sticking a piece of tape on the bottom, and turning the bot on.  It's moving 180° if that verifies anything.

Offline chelmi

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Re: $50 Robot Servos Stuck at Zero
« Reply #3 on: November 25, 2009, 03:58:10 PM »
If its only turning 180° it's not modified then. You need a continuous rotation servo, either modify a regular servo or buy it as is.

Chelmi.

Offline BinarySlaveTopic starter

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Re: $50 Robot Servos Stuck at Zero
« Reply #4 on: November 25, 2009, 06:31:04 PM »
Please don't ask how I misinterpreted the point of the servo modification, I have no answer :o  But I do have three shots now so it's back to the super glue!  Thanks to the both of you for pointing me in the right direction.

 


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