Stackable 24 Channel Servo Controller

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Stackable 24 Channel Servo Controller

Postby SolderSplashLabs » Tue Nov 13, 2012 8:44 am

Hi,

We are just finalising the design of our 24 Channel Servo Control SplashBridge.

Image

Were using an LPC11U24, it has a built in USB Stack in ROM with a Mass storage device bootloader so updating code it as easy and dragging a hex file into a removable drive. The Cortex M0 will be controlled either via USB (HID or CDC) or SPI. We have allowed up to 5 chip select lines so that these boards can be stacked. This means you *could* control up to 120 servo's. This board also plugs in to our SplashBase board which then allows you to control the servo's via your network.

I've posted a blog entry up here : http://www.soldersplash.co.uk/2012/11/2 ... ontroller/

Let me know what you think!

Carl.
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Re: Stackable 24 Channel Servo Controller

Postby matseng » Tue Nov 13, 2012 10:48 am

That's a sexy unit.... If I would do anything with a buttload of servos this would definitely be on my shortlist of possible solutions.

But shouldn't there be some more usable pins on it so it could handle 32 servos? Or did the soft-pwm's run out of steam at 24 channels?
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Re: Stackable 24 Channel Servo Controller

Postby SolderSplashLabs » Tue Nov 13, 2012 11:15 am

Thanks Matseng!

Actually I think we have 1 pin spare. Other IO is being used for the USB and Jtag header.
We have allowed for 5 SPI chipselect lines out and in. So that this board can be a master or a slave on the SPI bus. Push another board on top ( the 2 black sockets each side are stacking connectors ) and you have another 24 Servos on the SPI bus.
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Re: Stackable 24 Channel Servo Controller

Postby matseng » Tue Nov 13, 2012 11:28 am

Can the power rails to the servo headers handle current draw of 24 servos moving simultaneously? That could be some 15+ amps using mid sized servos....
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Re: Stackable 24 Channel Servo Controller

Postby SolderSplashLabs » Tue Nov 13, 2012 11:49 am

Yeah this is something were working on at the moment. We think were going to add a PTC to limit the current the board will carry based on the final track width.

For a large number of servo's external power can be supplied to the servo so that the board isn't carrying it.
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Re: Stackable 24 Channel Servo Controller

Postby SolderSplashLabs » Wed Nov 28, 2012 7:14 pm

Got the PCBs and parts on the weekend. Built it up and here is the first test :

http://youtu.be/ElURXxgs-nE

Thats all of the servos I could find/borrow but each output is working according to the scope.

So far so good, next is SPI coms to the SplashBase dev board and I'll have iOS control over them
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