VONF Explorer | RC Car With Microcontroller

About Us

We are two Argentinian teenagers, electronic technicians, both passionate about technology and electronics, and we are always looking for personal challenges and new learning.

Considerations

Please note that our native language is Spanish. You may notice some discrepancies or errors in the translation. Any corrections or suggestions will be greatly appreciated, as they will help us improve and add more value to the guide on our project.

How did the project come about?

The idea for the project came after hours and hours of searching and thinking about what we could do to bring closure to our career as electronics technicians. Finally we decided to make our VONF Explorer, a 1/10 scale radio-controlled car, which is 100% 3d printed and uses a transmission protocol created from scratch by ourselves, and most importantly, we don't use Arduino! (We have nothing against Arduino, on the contrary, we love using it and we think it's an excellent platform, only that one of the challenges was not using this platform).

What were the limitations?

The project itself had to be made up of certain points that we had to develop ourselves, such as:

• PCB Design
• Digital Electronics
• Analog electronics
• Mechanical design

Also, as a most important point, the project could not make use of Arduino or libraries for programming. So the biggest challenge was to be able to establish radio frequency communication using microcontrollers and creating our own communication protocol. Not least, our last limitation was trying to stay within a tight budget.

VONF Explorer, unlike most cars, has absolute sensitivity and accuracy, due to the use of ADC converters, and the robustness of the encoding protocol. It has rear and front lighting systems, battery level indicator, communication and ignition indicator LEDs, and an extra power addition to the engine by pressing a combination of buttons (programmed turbo).

Materials

Electronics:

x1 module RF 433Mhz (Tx and Rx) Buy

x2 pic16F886

x1 LM2596 Buy

x1 Motor Brushed 35T Buy

x1 Servo Motor MG996R (metal gears) Buy

x2 Joystick (speed and direction) Buy

x1 H-Bridge BTS7960 (for high current) Buy

x1 Li-Po Battery 2S 2200mAh 50C (for the car) Buy

x2 Li-Po Battery 3,7V 650mAh (for the joystick) Buy

x1 battery level indicator Buy

x2 Lm7805

x4 Capacitors 100nF

x2 micro-switch

x4 3mm high brightness blue LED

x4 3mm high brightness red LED

x12 3mm high brightness white LED

Some wires

Miscellaneous:

x2 bearings 8x12x3.5mm (rear wheels) Buy

x4 bearings 12x18x4mm (front wheels) Buy

Copper plate for pcb Buy

600g PLA

700g PETG

300g TPU

Various M3 screws and nuts of different lengths

Battery charger Buy

Tools

- 3D printer

- Printer

- Computer

- PicKit 3 programmer

- Cutter

- Screwdrivers

- Tweezers

- Minitool

Component Research & Procurement:

Before you begin building your car, it's crucial to research the necessary components, taking into account the cost and availability in your location. In many places, including Argentina, electronic components can be expensive and hard to come by. Therefore, it is advisable to look for more accessible and easy-to-acquire alternatives.

Consider reusing components from previous projects whenever possible. Components such as step-down supplies, regulators, joysticks, resistors, capacitors, among others, can be recovered from previous projects, helping to save money and resources.

3D Structure Evaluation:

Once you've gathered all the necessary components, evaluate whether any modifications need to be made to the car's 3D structure. This assessment should be based on the availability of materials and your available budget.

Carefully review the specifications of the purchased components, such as motor and servo motor, and compare them to the original design of the car. In some cases, minor adjustments may need to be made to the 3D structure to accommodate the available components. Maintain flexibility and creativity to find practical solutions that don't compromise the integrity of the overall project design.

Before printing the 3D files, make sure they are properly prepared for your type of printer. All files were designed to be printed on a 235x235x250mm FDM printer (Creality Ender 3 Pro), so you shouldn't have any difficulties on a machine of similar dimensions. Play around with different fill densities and number of perimeters for certain parts, such as wheel axles and engine block, for the best result. For greater durability and strength of the parts, it is recommended to use PETG or, ideally, ABS. For best car performance, both the tires and suspensions should be printed in TPU. (If you want and your budget allows, you can choose to buy the tires, these tires will give the vehicle a better grip).

To assemble the vehicle, we recommend that you follow the instructions in the incredible DukeDoks guide, which explains step by step in detail how to assemble all the 3D printed parts of the vehicle. Additionally, in your guide you will find a download link to the original files used in the chassis.

It is recommended to perform staged tests of each function of the car, using a current-limiting laboratory power supply instead of the battery, as the latter can supply a large amount of current, which could lead to a short circuit.

Start by testing the transmit (Tx) and receive (Rx) modules to make sure they are tuned to the same frequency. Create a simple program that sends a certain sequence of bits and check with LEDs or an oscilloscope that the information received is equal to the information sent.

Once the correct operation of the modules has been confirmed, the program can be loaded into the microcontrollers.

Once the programs have been loaded and the communication protocol has been tested, test the movement of the servo motor with the analog sticks. Note that the servo motor operates at a different voltage than the microcontroller, so you'll need to use a 5V step-down source for logic control.

With the steering running, test the speed and direction of rotation of the engine. For testing, it is recommended to use a lower current motor to avoid triggering the current protection of the source.

Finally, try the lighting features and the battery level indicator, among others. As a final test, it is recommended to test all features together.

Once you've done the testing of all the stages separately and together, you can start designing the PCBs using KiCad, a software that we find simpler to learn from scratch. For the process of creating the plates, we opted for the ironing or thermal transfer method due to its accessibility and reduced cost.

PCB for Joystick

For the design of the joystick PCB, we recommend that you try to make it as compact as possible, as it will then need to be placed inside a case. In our case, we use both SMD and THT components to reduce their size as much as possible. Once the board is printed, proceed to solder the SMD components first and then the THTs.

Downloading schematic and pcb from the JOYSTICK in KiCad

PCB for the Car

As for the design of the car's PCB, it presents a similar situation to that of the joystick, with a reduced space. This PCB includes connectors and terminals for easy assembly, as well as extra space to add functionalities. This board is composed of THT components only.

When using KiCad, make sure to follow the design instructions and carefully check the schematic before proceeding with printing the PCBs. Once printed, perform a thorough inspection to make sure all connections are correct before proceeding with assembling the components.

If you have any specific questions about the PCB design process or need additional guidance, don't hesitate to contact us. We're here to help you succeed in your joystick car construction project.

Downloading AUTO schematic and pcb in KiCad

Once you've prepared and printed the joystick PCB, it's time to create the 3D design of the joystick itself. For this stage, we recommend using Fusion 360 as our preferred software for 3D design, as we have access to their educational license and it offers an intuitive interface along with a wide range of tutorials available.

With Fusion 360, you'll be able to design the joystick efficiently and precisely, with both functionality and aesthetics in mind. It leverages modeling tools to create an ergonomic enclosure that fits comfortably in the user's hand and adequately protects the electronics inside.

Once the design is complete, proceed to 3D printing the joystick using PLA or another suitable material. Be sure to adjust the printing settings to your 3D printer's specifications and run tests to ensure high-quality printing and durability.

Remember that the appearance and functionality of the joystick are important, so take the time to design and make adjustments as needed. Once printed, assemble the joystick housing along with the PCB and other components to complete the functional unit.

After getting the vehicle working properly, it's time to add the finishing touches. In our case, we decided to put a case on it that would allow us to visualize the interior of the car to show its electronics. We also added stickers from different Formula 1 brands to give it a more authentic look. For the car's antenna, we simply use a 17 cm long telephone wire, which is equivalent to 1/4 of the wavelength, and place it inside a plastic tube for rigidity. Alternatively, you can buy a specific metal antenna for RC cars.

Also, consider mounting a GoPro camera on top of the car to record and get better visibility during operation.

For the joystick, you can add indicator stickers for each button, which will make it easier to use and provide a more professional look.

Congratulations! Now you can enjoy your new toy. Always remember to respect local speed limits and regulations to ensure a safe and fun experience for yourself and others. Have fun exploring all the functions and capabilities of your RC and joystick car!

If you need further assistance or have any additional questions, please do not hesitate to contact us. We're here to help make your build and use experience as rewarding as possible!

Our Emails:

Felipe: felivaccari@gmail.com

Nahuel: tobinanu@gmail.com