Introduction:
We like car and we like to build our own Atmel Mega32 MCU based radio-controlled NSX. We set three goals in the initial project proposal and they are as the following:
(1) Build a RC NSX with the same performance as the original car.
(2) Add extra features such as headlights and brake lights.
(3) Add distance IR sensor to avoid collision.
Our objective is to build a RC car with all the circuitries including two H-bridges, a 433MHz transmitter and a receiver, a remote controller and Mega 32 prototype boards. We expect it to perform or even out-perform the stock NSX with better steer and speed handling and longer operating range. We also want it to have some cool features such as distance sensor to avoid collision and brake lights to blink when the speed is lowered.
High level design:
Rationale & project idea:
We played RC car when we were small and now we are capable to build our own RC car and we like to make this hobby more interesting with some cool features that are hardly seen on the toy market. With a limited $25 budget, it made this tasks to be more challenging but also interesting. We were very clear to set out preliminary design and very careful to order parts.
Logical structure:
In this project, we use radio frequency to transmit and receive data and hence we implement this design with a transmitter end part and receiver end part. The receiver end has plenty of circuitries and the transmitter is relatively simple to build. The detail of hardware design is explained in next section. We were lucky enough to find a pair of cheap receiver and transmitter from www.radiotronix.com.
Two H-bridges are built to in this project . One is used to control the DC motor for speed and another is used to control the steering of another DC motor. We successfully had the stepper motor in the lab worked but we decided not to use it to provide variable turning angles for the steering. It was because we were unable to find gears to fit into the NSX and hence unable to test and determine if the output torque was large enough to turn the car.
Two prototype boards are built for the Mega32 MCUs. On the transmitter end, there is a 3-pot slide for varies speed control. Interpretation of the potentiometer value is handled with ADC0 of Port A. Four switches are used for left or right turn, headlights and bottom lights on/off and a last button for resetting the Mega32 MCU.
Parts list:
- RC NSX
- IN4001 diodes
- 74LS00N
- 74LS04N
- TIP31C
- TIP32C
- 150Ω, 220Ω, 10K, 100K resistors
- 0.1μ, 27pF capacitors
- 16MHz crystals
- LEDs
- voltage regulator -7805
- switches
Total cost: $21.27
The digital laboratory was our home for the past month and we had a very intensive schedule to occupy the workstation that we used to work at. We started early and finished the project just few days before the demonstration date. We managed to finish all three goals that we set for this project and it is amazing that we were ahead of our planned schedule. Generally, it was a fun project for us and we have met all our expectations. Our recommendation to the future groups is to set different goals for the project and start EARLY!
Read more: Radio Control Car