Control toy car transmitter with Arduino Uno

Question

Could someone suggest how I would go about soldering the necessary wires to a toy car transmitter so it can be connected to the pins of an Arduino Uno to allow the Arduino to control the car - forward, backwards, left, right. Could I solder wires to the pushbuttons connections? If so where?

Here is how the board of the transmitter looks.

enter image description here

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• Ignacio Vazquez-Abrams: Have you probed the circuit yet?
• Pete Kirkham: what's the id on the chip
• spangeman: Chip id now added in a second photo

Answer 1

First step: Check VCC level of this transmitter IC. If it is 5V then it is safe to connect power and ground of the transmitter board to power and ground of your Arduino. Just to power them together from one single power source.

Second step: most probably one terminal of each button goes to separate pins of the transmitter IC which pulls them high up to almost VCC level through some internal resistor (10-200 kOhms), while other button terminals are connected to the ground. You can check it using any voltmeter you have around. If voltage level on unpressed button is less then 0.5V lower then VCC - it is safe to connect those button terminals to your Arduino data pins and set those Arduino pins as usual digital outputs. Of course if first step was ok.

• spangeman: Thanks for the tips, VCC levels were fine. In case anyone else reads this I used a diode between the arduino pin and the pushbutton as discussed in the first scenario here - dduino.blogspot.co.uk/2012/02/trigger-buttons-with-arduino.html
• x4mer: Diode is ok. It makes sense to not feed current from Arduino into transmitter pins. Also it allows to power transmitter from lower voltage then Arduino (if needed).