RC Car Updates 5/14

Here are some more updates on the project. In my last update post, I pointed out that I was waiting on one last part to complete the prototype. I was actually waiting on some 2-to-4 decoders and I received them almost 2 weeks ago. As soon as they arrived, I popped one on the breadboard and constructed the circuit that I shared as a design drawing 2 posts ago. I was so surprised but it "just" worked!! I didn't have to tinker with it or anything, I just went by the design and it worked. I actually started on the software also, I will talk more about that later on. But I connected up the motor to it, and connected the two motor controller input pins to my microcontroller and applied a PWM signal, and it worked!!

More about the microcontroller side of the project: This is the first project that I am building that is using TI's C2000 Launchpad Microcontroller. This launchpad, which I believe is the second Launchpad that TI released, uses the C2000-F28027 Piccolo Microcontroller. It runs at 60 MHz, and it is capable of UART, I2C, SPI... On top of that, it has many other useful peripherals such as a EPWM peripheral. This is one of the 2 reasons I chose to use the C2000 Launchpad in my project. The other reason is that it natively supports TI's RTOS which they call SYS/BIOS. This is a real-time operating system and it is not too bad to use. I actually have some experience with it because I used a much more powerful C2000 working for Buckeye Current and we implemented SYS/BIOS on our motorcycle.

Since TI seems to have increased their prices for the MSP430 Launchpad, for another $8 ($18 in total) you can get the C2000 Launchpad and it very very capable. MSP430G2553 runs at 16-20 MHz tops and the C2000 Piccolo runs at 60 MHz! The only down side, I would say, is when you are done with experimenting and prototyping, you can't just take out the Piccolo microcontroller from your Launchpad and place it on a Perf Board, or a breadboard. The packaging doesn't allow that, and the Piccolo is soldered on the board, whereas the MSP430 comes in DIP packaging which you can pry out and use on an external circuit (like I did in my Car Trip Computer Project).

Last thing, the PCB layout I shared 2 posts ago has been put off for now. Instead of making a separate board just for the motor controller, I decided to make one big board that will house the motor controller, the C2000 LP (sort of like a "BoosterPack" where LP will plug onto the board), and the RF module. Speaking of which, I do have the RF Modules! I got a pair of surprisingly little RF modules that broadcast at 433 MHz. They use the TI CC1101 RF chip and they handle error-checking and all sorts of other things by themselves! Down side, it has 105-page datasheet and nearly 1 billion registers (exaggerating) that I will have to go through :( The other down side is that the boards came with 0.05" pitch headers?!!! I am going to make a breakout board to convert that to the much more standard 0.1" pitch header, so I can breadboard it. Last thing, I will be using SPI to talk to the RF modules.

-Anil