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This board was designed for use as a general prototyping board, as I needed something a little more robust then my previous one. The main reason for building this, was that I needed a serial connection to a PC for debugging. It's hard to learn ADC's, Timers, PWM etc. without being able to actually see what is going on inside the microcontroller. I chose the dsPIC30F4011 because it seemed to be a good general purpose microcontroller and had all of the above features.
I started off by searching the internet (using Google, what else?) for PIC boards that had RS-232 capability. By far the most helpful website was NorthWestern's PIC RS232 - Mechatronics Wiki. In addition to having a nice schematic of a MAX232 IC connected to a PIC, they talk about USB to RS232 adaptor cables, and adress issues such as why level shifting is even necessary.
A MAX232 IC (Integrated Circuit) is needed because a PIC runs at +5V (outputs thus being 0V through +5V), while a computer's serial port runs at something like -12V through +12V. Obviously I didn't try this, but you can image that bad things would happen if you hooked up 12V to a PIC microcontroller. The MAX232 chip takes the 5V signals coming from the PIC (going to the computer) and steps it up to the voltage that the computer uses. It also takes the higher voltage coming from the computer (going to the PIC) and steps down the voltage to the level that the PIC uses.
I ended up using a Texas Intruments MAX232IN as my level shifting chip. If you're like me, a student with no money, they have a samples program
After knowing the parts needed, it's time to make the schematic. If you don't have a favorite schematic(ing) program, there's a great piece of software for making schematics (and even PCBs) called Eagle Layout Editor, which is available for free at CadSoft Online.
The schematic on the right is the first that I made with Eagle Editor. Actually, it is the first schematic I ever made, so apologies if it's hard to read.
The parts list below shows the cheapest prices that I've found. Usually you will need to purchase ten or more of a given part at a time to get prices like these, purchasing individual parts raises the price drastically. Remember it will actually cost more because of shipping costs and try to buy them all from one supplier, I lost some money in purchasing the parts in different orders (more shipping costs...).
Parts List
Now that the board is done, it's time to write the software! All this program does is send the message "Hello World!" (cliché, I know..) to the computer to be read in a terminal program, but it's a good starting point from which to develop a more robost framework in the future (Actually I've already started). You can download my code on the software page.
Hello World!
Some pictures of the finished board
You can find the dsPIC30F4011 board file in the downloads section.
