How to wire wixel, motor controller, motors and servo

Hi,
I have some questions about my project. I have two wixels, one qik dual motor contoller, two motors and one servo and need to put it all together. One wixel will be running usb to radion wireless app the other one(visible in schema) will run extended wireless app with support for servos. Please open the picture to see circuit schema. Regarding the circuit I have lot questions maybe someone can answer them(or at least some of them).

  1. can I use one power source for motors, servo, logic?just use some voltage dividers to lower the voltage to 3.3 level. It will be only one common ground is that possible? If the servo need to be controled by Wixel, it needs to have same ground like Wixel, is it right?

  2. Connecting just TX-RX pair is enough to daisy-chain the Wixel with controller? The chain will immediately work, when the Wixel wireless app mode is radio2uart, am I right?

  3. The servo and motors like 6V voltage, so I suppose the best voltage of the power source will be 6V(i.e. pololu.com/catalog/product/2243)

Thanks for answer and your time spent by reading this novel:)

Martin


Hello, Martin.

Your schematic is mostly correct. The connection from the Qik’s TX line to the Wixel is optional, but if you do it you will need to have a voltage divider because the Wixel’s pins are NOT 5 V tolerant. Your schematic makes it look like the 3.3 V GND and the motor GND will be different; unless you are doing something very special, all the grounds in your system should be connected. Also, you didn’t say which model of Qik you have and it makes a difference, so there might be other things wrong with your schematic.

Yes, but please read the paragraph that starts with “While it is possible to use the same power source for both your motors and logic, we do not recommend this.” in the “Power and Motor Connections” section of the Qik Qik 2s9v1 User’s Guide.

I don’t think there’s any daisy chaining in your schematic. You are simply connecting one serial device to another. Yes, this setup should work and allow you to control the Qik using an unmodified version of the Wireless Serial App.

Yes, just make sure it can provide enough current for all your components. It would be safer to use one of our higher capacity battery packs such as this one:
pololu.com/catalog/product/2223
Also note that a fully charged NiMH cell will deliver almost 1.5 V, so that 5-cell pack can measure over 7 volts after being charged, and it can fall well below 5 volts when the pack is drained.

–David

Thanks,
the controller I’m using is exactly 2s9v1. The TX does’n make sense, my bad, just don’t get the note about voltage(does it mean the TX output from qik is 5V?). Why I wrote daisy is because the Wixel needs also to hear the communication(controls servo) so I plan to use kind of same protocol for Wixel aswell(in my customized wireless app).

My application is kind of weight critical, so this is why I’d like to spare some with the common power source.

Thanks for the review.