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Topic: questions about chaining RGB LED+servo modules using WS2801 chips.. control? (Read 4 times) previous topic - next topic

doorless

hello to all !

i'm new to all this so please excuse my ignorance..:)

i'm constructing a fixture that requires me to build a whole bunch of modules, chain them all together, and have them all controlled by a single computer using the ART-NET protocol.

each module will have 1 RGB LED connected to a WS2801 chip, and 1 servo motor also connected to a WS2801 chip.

Servo info: http://www.aliexpress.com/product-fm/497600351-Freeshipping-DC-5V-Stepper-Motor-Geared-for-Arduino-PIC-MCU-DIY-28BYJ-48-5v-28BYJ-48-wholesalers.html
LED info: http://www.aliexpress.com/product-fm/463271409-8mm-Round-LED-Common-Anode-Diffused-RGB-Color-wholesalers.html
WS2801 info: http://www.adafruit.com/datasheets/WS2801.pdf

all the modules will be chained together in a row, finally plugged into an Arduino Mega 2560 + Ethernet Shield + Xbee wireless Shield. The Arduino will communicate with the computer using the ART-NET protocol, threw the Ethernet cable or via Wi-Fi.

Basically, my questions are:
1. Is the WS2801 the right chip to use (i heard it can also drive a servo motor)?
2. What are the 5 wires on the servo motor? how do connect it to a WS2801 chip?
3. Are there any other cheap chainable driver chips that have 5-6 channels (i could then connect both the RGB LED and the servo motor to a single driver chip, instead of using 2 WS2801 chips in each module)?
4. Is there a limit of how many modules i can chain together? After how many modules would i need to inject more power to the module chain?
5. How difficult is it to get the Arduino to function using the ART-NET protocol threw the Ethernet Shield or using the Wi-Fi Shield.
6. How does the Arduino know exactly how many modules are connected?
7.. Is this at all POSSIBLE ???

I posted a diagram bellow:

Thanks !
-Mickey

KirAsh4

The WS2801 only has three channels.  That servo has five.  See a problem there?  I'm not sure where you're trying to go with the WS2801 since it's an LED driver, not a servo driver.

doorless

the specific type of servo is less of an issue, i can also use a regular RC mini servo that has 3 wires, all i need is for the motor to turn forward and reverse.

the reason i mention the WS2801 chips is because they can be chained together for use with 3 channel LEDs, can it also be used to drive a small servo forward and reverse?

is there any other chainable chip that can drive LED's and a servo (maybe 6 channel)?

thanks!
-Mickey

KirAsh4

You need to figure out (a) how much current the servo needs, (b) how many legs it needs, and (c) whether it works with PWM ... at the very least.

WS2801 (3 channels) produces a PWM signal to drive the LEDs, and you can drive it in either constant current (up to 50mA) or constant voltage (up to 100mA).  You have to figure out which works for whatever servo you decide to use.

As for more channels, there is the WS2803 which has 18 channels.  That one only provides constant current up to 30mA.

I have no clue if either will work for driving a servo.  You're on your own there.  Both of those provide a PWM signal.

doorless

OK
let's say the servos manage to work with the WS2801 chips, what about the arduino?

Is there a limit of how many modules i can chain together? After how many modules would i need to inject more power to the module chain?
How difficult is it to get the Arduino to function using the ART-NET protocol threw the Ethernet Shield or using the Wi-Fi Shield.
How does the Arduino know exactly how many modules are connected?
Will this all work stably? what should i look out for?

Thanks for the help KirAsh4!

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