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maestro polulu

Posted: Thu Nov 01, 2018 1:15 pm
by icnxt
Hi there could u please tell me if i can use openmv with maestro polulu servo controller and how would i connect it up many thanks in atvance

Re: maestro polulu

Posted: Thu Nov 01, 2018 5:02 pm
by iabdalkader
icnxt wrote:
Thu Nov 01, 2018 1:15 pm
Hi there could u please tell me if i can use openmv with maestro polulu servo controller and how would i connect it up many thanks in atvance
Does it have I2C, UART or SPI ? If so, you can use it with an openmv camera.

Re: maestro polulu

Posted: Thu Nov 01, 2018 11:59 pm
by icnxt
Hi there it only has TTL tx rx as serial input and output and txin daisy chain input

Re: maestro polulu

Posted: Fri Nov 02, 2018 7:40 am
by iabdalkader
icnxt wrote:
Thu Nov 01, 2018 11:59 pm
Hi there it only has TTL tx rx as serial input and output and txin daisy chain input
It should work with the camera.

Re: maestro polulu

Posted: Fri Nov 02, 2018 12:47 pm
by icnxt
That is great new how would i conect it and could u please help with color track with pan and tilt with that board Many thanks

Re: maestro polulu

Posted: Sat Nov 03, 2018 1:48 pm
by kwagyeman
Hi, please see the pixy emulation example scripts.

Re: maestro polulu

Posted: Mon May 27, 2019 10:48 am
by kwiley
I worked with the Pololu SV203 for years. I have about eight of them lying around my house now and have always thought about incorporating them into more recent projects, but like you, I have had to consider how I would interface them. As indicated above, it'll depend on getting a serial connection up and running, and then you'll have code up the serial commands that the Pololu relies on. For the SV203, it was a fairly small dictionary of string commands that would drive the servos, convert their control lines to digital switches, or read values from the A/D lines -- or as you indicated in your post, further commands to daisychain multiple Pololus together.

One thing to be very very sure about is that it is TTL. The SV203 was RS232 and I had to fiddle with MAX232 chips to get the voltage conversion right. But you said your Pololus are TTL, so you should be good to go. But be sure. Also, I'm curious to hear from the creators on 3.3V vs 5V. I think the Pololus' TTL is 5V. OpenMV is described as 3.3V with 5V tolerance. One way of reading that is "You really ought to use 3.3V with OpenMV but 5V is okay if you really must." Is there any cost to using 5V with OpenMV? While "tolerant" does it wear out some aspect of the electronics faster? If not, does it incur a higher electrical cost (current) perhaps to perform the voltage conversion or dissipate the heat? Or, alternatively, is communicating with a 5V I/O device from OpenMV just perfectly fine?

Please let us know how your Pololu project goes? It would give me some insight into eventually bringing my SV203s into the picture.

Re: maestro polulu

Posted: Mon May 27, 2019 4:02 pm
by kwagyeman
STM32 chips can handle 5V inputs without issues. They will not break. They only output 3.3V however.

This is one reason we like STM32 chips. They have I/Os designed for this.

Less returns on parts. Imagine how many broken OpenMV Cams there would be otherwise.

Re: maestro polulu

Posted: Mon May 27, 2019 10:52 pm
by kwiley
Excellent. Thanks for clarifying that.