Brownout with Arduino Nano

Question

I'm making an RC car with the Arduino Nano. I'm using RF433 as wireless communication with 2 motors and L293D as the motor driver. I use 4 1.5V batteries to power the Arduin and another 6V battery pack to power the motors, and a joystick with an Arduino Mega to send commands through the RF433 to the Arduino Nano.

I've written a program that sends specific digits when the joystick is in a certain position, i.e. when the joystick is "bent" to the front it sends a "1", a "2" is sent when the joystick is bent towards the back, and so on.

My problem is this:

When I bend the joystick towards a certain direction, the RC car moves accordingly without problem; However, when I bend the joystick towards another direction the RC car doesn't respond.

I took a look at what the RC car was receiving, and I've noticed that after the first command was sent (when I bend the joystick towards a certain direction), no more commands get to the RC car (in other words the Arduino Nano), and this occurs occasionally. I think this means the Arduino Nano "froze" after the first command.

Answer 1

You have at least three problems here:

1) First and most critically, a nominal 6v pack does not meet the input voltage requirements of the regulator used an Arduino even before it gets loaded down by a motor, and it only gets worse under load

2) L293/L297 and similar bipolar bridges have absurdly high internal losses, so are unsuited to low voltage systems - effectively one of your cells goes just to feeding the wasteful driver chip. Use a modern and efficient FET driver like a TB6612FNG, or else add another cell to the pack.

3) The 433 MHz RF modules are notoriously low fidelity, and in many places not permitted for the control of RC models anyway. You'll have much better results with the sophisticated digital radio modules sold at comparable prices for 2.4 GHz, which are incidentally the functional equivelent of what most RC toys now use (and actually in many cases can be made interoperable with them).

Granted, you may well have other issues as well, such as errors in your software.