Confused about how to drive a rc car using arduino

hi folks, I am trying to build an autonomous car by attaching my arduino uno r3  to my rc car. Please pardon me if there are certain stuff I don't understand as my electronics knowledge has long vaporised since my education days and im starting from zero again.

In particular, i'm using this guide as my RC car is also using a RX-2B chip.

So I've followed the steps.. but made a mistake. 1. Instead of attaching a seperate battery to power the uno, I connected Vin to Vcc of the RX-2B, while still using the same ground.

Now, to test the circuit before commiting, I let the UNO output a HIGH signal on pin 2 and use a jumper wire to probe the pins from the control chip. For the left and right signals, they work well - touch the correct pins, bam! the wheels turn.

However, for the forward and backward pins, when I probe them, the motor only register a very very small movement. Initially, the impression is insufficient current. However, when I do the same with the 5V pin from arduino, the motor runs perfectly.

So, my questions are:

1. Reading the uno datasheet, the 5v pin and digital pins both outputs the same voltage and current. Why the latter works and former don't?


I will agree that it doesn’t make much sense.

The toy is being driven by the same logic levels that your UNO can output. I can only guess that the RX2 chip has similar limitations related to current.

Worst case scenario, you have to add a couple transistors with their associated resistors to drive the vehicle forward/reverse.