YA Project - TheEYEbot

Quite a while back I had the idea of making a tentacle eye type animatronic thing…
I got a fair bit along then… Well…
It is sitting in a box waiting for me to get started again…

But then something in the freecycle pile caught my eye (and I find starting a new project way more fun then finishing one)…
A pan & tilt video camera


Once opened up I saw it had sort of a giant eyeball…

Just the perfect thing to add the OLED eye display I had already built for the Tentacle project…
And the pan and tilt mechanism is already in place with a (1997 era) controller system…
Of course the question was did it work…
So I mounted it on a hunk of plywood (to make it easier to muck around with and started to play…

It`s a Sensormatic Speeddome 2000 PTZ unit…
It did have a camera but it had been removed (which was fine with me as I just wanted the pan & tilt function). It does appear to have a fair bit of electronics for the camera so hopefully it will function without it.
It actually has full 360 degree pan as it has a slip ring assembly to bring power and signaling to the center ball section (which does the tilt)
It is controlled by a RS-422 connection using the manufacturers own protocol and is powered from 24VAC
Time to find a power source and see what happens

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The good thing is that mechanically the innards look almost brand new and it doesn`t look very used so hopefully that means minimal ware on the mechanisms…

The pan and tilt are controlled by simple DC motors that have 2 channel quadrature encoders so if the electronics don`t work I should be able to set something up with a Nano and a H driver…

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Did some web searching and was able to fid a a bit of info. Found a few install manuals that have details on the pinouts and PCB settings. And managed to find info on the control protocol. All seem to be for later models so hopefully this one is similar…

Got a 24V transformer and hooked up power…
No joy…At least no smoke…
The main PCB has LEDs for +5V and +12V… All I got was a clicking from the power supply (an external switching model and the LEDS flashed on every click… Disconnected the +5/+12 feeds from the power supply to the PCB and powered it up again. Power supply still does the same thing so it appears not to be the PCB causing the issue. A web search on switching power supply troubleshooting suggests the clicking and pulses of power are a sign of the overvoltage crowbar circuit shutting things down on the power supply (hopefully saving the PCB from overvoltage). This could be due to dried out caps or ??. So I pulled off the power supply and opened it up…


Could not see anything obvious but it is almost 25 years old so caps could easily be bad…
Decided to power it from a stand alone power supply…

And success!!! Once power is applied it seems to boot up and do a few spins (think it is a calibration sequence) and then it moves into a position that is the same every time.

Went to Lee’s and got a USB-RS422 adapter to work on figuring out the control protocol. Looked at various apps for monitoring serial data (the control data is not ASCII test so normal terminal software doesn’t help. Ended up using Realterm. Set it up for 4800 bps, 8N1 and connected it to the terminal block…

Powered up the PTZ and after a seemingly long wait it went through it’s boot up routine and spewed out a "0x01 0xC1 0x3E’ which based on the protocol info is it’s ACK message and what should be sent. the first byte is the address (01), the second byte is the ACK code (C1) and the third is a checksum that is calculated by adding the address and control bytes, then subtracting that total from 0, then using the least significant byte as the checksum (3E)…

It actually sends the string 3 times as it wait for an ACK from the controller but then gives up…

So success in that the unit seems to function…
Now time to see if I can control it…

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I’m happy when I can get an Arduino, ethernet and a temp sensor all talking together - PacketBob takes a junked PTZ camera and hacks it into an EyeBot!
Looking good, great job