Arduino in combination with RC transmitter/receiver

Hello,

First I would like to introduce myself. I’m Sven I live in The Netherlands. I have ordered a Arduino Starter Kit and a Arduino Mega. The reason why I want to use Arduino is:

I’m currently busy with building an 1:14 RC truck. In this model I would like to build in lights (fog lights, winkers, brake lights etc).


This is the current situation. The servo’s are being attached to the Spektrum receiver and this works fine. But I would like to attach all the servos and Leds to the Arduino.

I would like to program multiple programs in the arduino. In the first program I can use the servo’s for steering, lift an axle etc.
In the second and third program I can turn on/off the specific lights.

I have thought about it and I think it’s possible to switch between the programs with a 2-position switch on my RC transmitter. Everytime I hit the switch it will increase an integer by 1.

With all this info I have made an schema with the Arduino and the current devices combined:

I’ve read that I need an external power supply for the servo’s. Is this schema correct? Any tips and improvement are welcome. If anything isn’t clear, let me hear you.

Greets,

Sven

You need a connection between the GND of the 9V battery and the GND of the 7.2V battery. In general there should be a connection between the GNDs of all power sources in any project. But really you don't want the 9V battery; you should connect the 7.2V from your battery pack to the Arduino directly (the barrel jack or the Vin and GND pins which are equivalent to the barrel jack). No need for a second battery.

http://rcarduino.blogspot.com/ has a lot of info you might find useful in figuring out how to read the signals from your receiver.

Thank you for your reply. I've read many articles on the internet and a lot of them suggests that an external power supply is needed for a correct working of the servo's, like this: |500x257

But according to you, I can replace the GND and + from the servo battery pack with the GND and 5V of the Arduino? Is 5V enough to power 5 servo's and about 35 LEDS with only a 9V battery to the DC jack? Or should I use my 7.2V 4600 mAh racing pack for the power supply at the Vin Pin?

The servos are likely to create some nasty surges on the power line as they stop & go & change direction, etc. To avoid the Arduino from resetting when that occurs, using 9V to power the arduino and the 7.2V battery for the servos makes the most sense. However, the battery pack is pretty hefty, 4.6AH, so it could b "stiff" enough to not be bothered by the servos. Go ahead and power the arduino from that also; operation might get erratic as the battery drains down and the servos start impacting the voltage level. If that's going to be a problem than keep 2 supplies. DO connect all the Gnds together tho.

Thanks for your reply. Do I have to add the GND from the 2.1mm DC jack manually to the GND port or is that already arramged by the Arduino itself? Can you perhaps make a drawing with the schedule how to connect the two power supplies to the Arduino?

RidgyFive64: But according to you, I can replace the GND and + from the servo battery pack with the GND and 5V of the Arduino?

No, I didn't say that. In your second picture from your original post you showed that your servos were getting their power from the servo-like connector on your motor speed controller (you show a red and black line connecting to the breadboard from that speed controller). That is where they should continue to get their power from. And to be clear that's not 7.2V coming out of those wires but rather the speed controller has an internal, 5V regulator providing power to those lines -- it's referred to as a battery elimination circuit (BEC) and almost all motor speed controllers have them.

As to whether the motor speed controller's BEC can provide enough amperage for five servos is hard to say; you're going to have to just try it out. If you see weak or erratic behavior from your servos then you might have to go back to the hobby store and buy a dedicated BEC (or preferrably a "UBEC") for the servos.

Regarding connecting GNDs, I did mention that Vin and GND are equivalent to the pins in the barrel jack, and I'll expand that to say that any pin labelled GND on the Arduino board is equivalent. So long as any one of those GND pins on the Arduino connects to any black line on your speed controller or 7.2V battery then you will be OK.

I am now a little bit confused of all the electrical terms. But I have understand your story. The Speed controller sends 5V output to the receiver so the servo's on the receiver are getting 5V Right? The black and red wire from the arduino to the speedcontroller is to power it. the servo-like connector of the speedcontroller is plugged into the receiver.

But now I would like to have clear what the basic schema is for attaching the racing pack to the Arduino. I use the Racing pack to power my speedcontroller. Should I create a Y-cable construction, so the power pack will suply the Speedcontroller and the Arduino? Do I have to attach the racing pack to the Vin port / GND and that's it? And then connect the 5V and GND to the breadboard for power supply of the servo's?