sparkfun Open Servo

Discussions relating to development and use of the OpenServo hardware.

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boogui
Posts: 2
Joined: Wed Aug 18, 2010 12:17 pm

sparkfun Open Servo

Post by boogui » Wed Aug 18, 2010 12:32 pm

hi everyone

i'm new to open servo, i just bought one from sparkfun, wich seems to be a V2.7 . there is no instruction to make it work, so i need a little help.
i'm currently sending a +5v I2C signal from a pic2420, is the OS at the same line level (no 3.3v)?
what is the address, i've tried fro 0x10 to 0x20, no move...
is the firmware already loaded, cause i can't get any sign of life in it, even the motor don't react at power up, is there a way to control. i did test 5v at the output of the regulator, i'm powering with 7.5V 1amps.
my I2C looks like, start, adress,0x10 (for moving to position),0x03,OxD4 (position),stop is it correct?
best regards

:roll: :roll: :roll:

jharvey
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Location: Maine USA
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Post by jharvey » Thu Aug 19, 2010 8:33 am

I'm not very familiar with that version, some things I know about the OSV3 version is that it needs a rock solid 7.2v supply, just like RC battery packs supply. Some steps required to make it go to a position include setting the PID values or at least the P value, setting a position, and turning on the motor PWM.

A basic read of the position(s), that changes as you rotate the servo shaft might be a good first step. That would help ensure you have working communications, ect.

I know that you can use the PIC I2C, but I'm not that familiar with that approach. I'm using an OSIF from robotfuzz.

http://robotfuzz.co.uk/OSIF

It's powered via USB so I would say yes you are good for 5V I2C. This comes with test software that will allow you to confirm basic operations of the servo. In my case I found I had a bad power supply. My bench supply typically gets cranked up to a 5 amp limit, and I know it won't work on several lower current limits. I'm not sure if 1A is to low or not.

I know the OSIF software has a scan option that will list all devices on the I2C. This is where you find the address. Mine came with a default at 0x10, so yours is likely 0x10, but I would recommend scanning the bus.

boogui
Posts: 2
Joined: Wed Aug 18, 2010 12:17 pm

Post by boogui » Thu Aug 19, 2010 8:57 am

thank you jharvey

i just ordered the OSIF, hope it will be usefull

i 'll try with another power supply or a battery packs.

:shock:

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