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Author Topic: Serial Servo Control Question  (Read 572 times)

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Offline strat321Topic starter

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Serial Servo Control Question
« on: February 16, 2014, 01:32:04 PM »
My setup is as follows: a kondo serial servo connected to a pool 8 serial servo controller connected to an axon ii mcu. The MCU has a 5v power supply while the servo has a 12v supply. An analog sensor is connected as well to control the servo however there is no response. Please help. Thanks!

Offline jwatte

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Re: Serial Servo Control Question
« Reply #1 on: February 16, 2014, 01:48:24 PM »
You will need to post a schematic.
Also, you will need to post code snippets for what you're trying to do.

To help with troubleshooting, try doing just one thing. For example, try reading the sensor, and turn on/off a LED with it. Make sure you can get that to work.
Then, try turning the servo back and forth with a delay, without any sensors. Make sur eyou can get that to work.
Then, combine the two.

Offline strat321Topic starter

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Re: Serial Servo Control Question
« Reply #2 on: February 16, 2014, 03:22:33 PM »
I tried just operating the servo via the default program generated by Webbot PD. The light on the servo blinked when I connected it's power supply and the light on the Pololu controller turned on in conjunction with the MCU's power. Is there possibly a transmit error??? Schematic on the way...

Offline strat321Topic starter

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Re: Serial Servo Control Question
« Reply #3 on: February 16, 2014, 03:32:56 PM »
here is the schematic that you requested, ignoring the analog input as i was able to get that to demonstrate success in a hyperterminal

Offline jwatte

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Re: Serial Servo Control Question
« Reply #4 on: February 16, 2014, 07:28:50 PM »
Does the servo and all the boards share ground? You have to tie the grounds (- connections) together.

Also, if you say the servo is serial, are you using a serial-output controller, or a PWM-output controller?

Offline strat321Topic starter

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Re: Serial Servo Control Question
« Reply #5 on: February 16, 2014, 07:43:49 PM »
I apologize, can you clarify the meaning of "sharing ground"? I am using a pool 8 serial servo controller (http://www.robotshop.com/en/pololu-micro-serial-servo-controller.html) and a kondo ics servo (http://www.robotshop.com/en/kondo-krs-6003hv-ics-servo-motor-red-version.html)

Offline jwatte

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Re: Serial Servo Control Question
« Reply #6 on: February 17, 2014, 12:38:23 PM »
"sharing ground" means that the GND pin (- of battery, or "GND" terminal) on the Axon needs to go to "GND" (or - of battery) on the Pool 8, and in turn needs to go to "GND" (or - of battery) of the 12V battery/servos.

Offline strat321Topic starter

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Re: Serial Servo Control Question
« Reply #7 on: February 17, 2014, 03:33:30 PM »
In my configuration in which the gnd of the axon ii and pololu (just realized auto correct changed that to pool) in my previous posts) is shared with the axon and the servo is only connected to the servo controller with the I/O line (the power is direct to the servo).... is this incorrect?

Offline jwatte

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Re: Serial Servo Control Question
« Reply #8 on: February 17, 2014, 06:45:26 PM »
Yes, you need to connect the - of the servo battery to the GND/- of the other circuits.
A signal needs two conductors for the current to go there and back. If you only have one conductor, no current (or very little current) will flow, and thus the signal won't be received.

Offline strat321Topic starter

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Re: Serial Servo Control Question
« Reply #9 on: February 17, 2014, 07:43:44 PM »
Ok, now obviously the (-) of the bat still needs to be connected to the servo so should I just split the wire? Thanks!

Offline jwatte

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Re: Serial Servo Control Question
« Reply #10 on: February 18, 2014, 11:58:49 AM »
Yes.

Offline strat321Topic starter

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Re: Serial Servo Control Question
« Reply #11 on: February 18, 2014, 02:47:36 PM »
Alright I tried this... and the servo is still not responding

Offline knossos

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Re: Serial Servo Control Question
« Reply #12 on: February 18, 2014, 04:58:52 PM »
First of all looking at the Kondo servo it is serial controlled not PWM controlled so you can't use it with the Pololu controller.  A quick search turned up this C library for ICS communication with Kondo Servos.  Hope this helps to get you started.
« Last Edit: February 18, 2014, 05:07:10 PM by knossos »
"Never regret thy fall,
O Icarus of the fearless flight
For the greatest tragedy of them all
Is never to feel the burning light."
 
Oscar Wilde

Offline strat321Topic starter

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Re: Serial Servo Control Question
« Reply #13 on: February 18, 2014, 05:02:26 PM »
Ah thankyou very much however the link seems to be broken...

Offline knossos

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Re: Serial Servo Control Question
« Reply #14 on: February 18, 2014, 05:05:47 PM »
I corrected the link in the previous post. (I had an extra space in there on accident.)
"Never regret thy fall,
O Icarus of the fearless flight
For the greatest tragedy of them all
Is never to feel the burning light."
 
Oscar Wilde

 


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