recently bought an UNIROI Smart Car kit. (UNIROI Smart Robot Car Kit Arduino Robot Kit with 4 Wheel Drive, Arduino UNO R3 Board, Ultrasonic Sensor, Infrared Tracking Module (No Welding Required) https://www.amazon.co.uk/dp/B07CWS344R/ref=cm_sw_r_cp_tai_wQExCbHT0YM8K)

I bought some extra things with it to make it more interesting, but the problem is is that I need to connect more pins to the Arduino but they are all taken up by the car. What I have noticed is that there are these extra pins along the side of the Arduino board as you can see here: https://imgur.com/a/j1Q8QVu

I know you guys don’t have it in hand, but I thought I’d give it a shot to see if any of you know I can use those pins. The description of the car also quotes “Extended Pin Interface. The chassis is designed with extended pin interface for Arduino UNO, only need to solder pins for using, more convenient to develop and build your own robot car kit”

Appreciate any help you guys got.


It seems that you'll have to do some extended modifications to the design. In fact, all Arduino Pins (D0 - D13, A0-A5) are connected to components on the board and thus in use.

Schematics and Code: https://mega.nz/#F!Xbg1FA5L!qGah_HlLFJ_NKxv7ILLY2g folder "5 SCH".


This means that the only way that you'll get new components into this project are:

  • removing components and re-programming the firmware to not use them
    • e.g., the two tracking-sensors left&right -> A2 and A3 are free
    • e.g., the speaker pin (D13). Who needs a speaker?
  • restructuring components
    • e.g. for the analog sensors: instead of using the Arduino's analog pins, throw a I2C ADC module (e.g. ADS1115) in the build and change the firmware to get the analog values via that new module; making this project use an I2C bus will free all analog pins and cost 2 pins (SCL + SDA). The I2C bus has the additional benefit of being able to connect more than one device to it -- you can e.g. put a I2C GPIO expander (e.g. MCP23017) on it to gain 16 more digital I/O -- more than the Uno had to begin with.
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  • Appreciate the reply. Do you think if I removed those tracking sensors and and ultrasonic sensor I could add an SD card module that takes 4 pins? They are also anolog pins so can I still use them as digital? As a side note, I also have a spare Arduino so would it be possible to receive signals from the avoid sensor to both Arduinos? – Josh Feb 8 '19 at 21:38
  • @Josh your SD card is a SPI device and must be connected to the hardware-SPI pins of the Arduino Uno, which are 11,12,13 (MISO, MOSI, SCLK) and any other digital pin for slave-select (SS). On your car, these pins are connected to the servo (D11), the button and the speaker, so you would have to re-locate all these components.. Or use a bit-banged SPI in software, which I haven't yet seen. And yes, the analog pins A0-A5 are all capable of outputting digital output (HIGH,LOW). – Maximilian Gerhardt Feb 8 '19 at 21:42
  • I wouldn’t be able to move those items, they’re attached in a way I wouldn’t know how to re-locate, but I appreciate the suggestion. What about using another Arduino? Since I am not great at coding when there’s tons and tons of lines, having a second Arduino that also reads the avoidance sensors would be perfect. Is that possible? – Josh Feb 8 '19 at 23:44
  • @Josh you could upgrade the entire thing to an Arduino Mega instead of the Uno.. should have similiar code but you have tons of I/O pins more. – Maximilian Gerhardt Feb 9 '19 at 13:02

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