Hello,
I need to code a MPPT algorithm for my push-pull converter graduation project. The C code for MPPT algorithm is almost ready but i have big problems about configurations of the PIC. There are bunch of examples in internet for DSPIC18 with CCS C however, i could not find many examples about my PIC(33EP16GS502).
I am real beginner to the digital world. I could not really understand the procedure of setting up the configuration. For example;
There are built in functions in CCS for PWM generation such as:
bif void setup_hspwm(unsigned int32 settings, unsigned int16 period);
_bif void setup_hspwm_secondary(unsigned int32 settings, unsigned int16 period);
_bif void setup_hspwm_unit(unsigned int8 unit, unsigned int32 settings); etc.
I want to know which function i should start coding and how to continue.
Any help would be very appreciated.
Hi Gökhan,
my following answer might look a bit outdated in an age when every big manufacturer of microcontrollers seems to offer an "abstraction layer" library, and the Arduino approach has entered even the universities ...
When I start with a new type of microcontroller, first I want to learn (roughly) its properties and its performance at some low level tasks. The only reliable way to get to know this is reading the datasheet, of course not cover to cover but only the most interesting parts (related to my current project).
If you are new to the digital world this is perhaps a hard task, and you might not be successful in every aspect. But (as with most things) with growing experience it becomes easy rapidly.
I seem to remember that with dsPICs, one peculiarity is that there is not one large datasheet but only an overview and a bunch of chapters available as separate pdf files (about 40, referenced in the overview).
Knowing the basics of C, and after you've got a rough grasp of a certain peripheral unit (e. g. a timer with PWM ability) you can easily configure this unit. The best start is to disconnect any additional hardware from the microcontroller board (so faulty software cannot damage anything), and to look at the expected PWM signal with a scope.
If you have come successfully this far, you have learned something that is easily transferred to all kinds of microcontrollers because the register names and the function of control bits might vary but the general function of a timer capable of generating a PWM signal is the same everywhere.
Now you can still use the abstraction layer library functions but:
- You have additionally to learn the effects of each function related to your task, and its interface.
- What you will learn about the abstraction layer is of no use if, in the future, you would switch to microcontrollers by another manufacturer or perhaps just to another family. The use of the abstraction layer would probably pay off if you would program the same family of microcontrollers for the next couple of years, solving quite similar tasks. (I wish you a much more exciting professional future! ;-)
So, my advice is: Look in the overview datasheet of the dsPIC33EP for timers with PWM, download the respective chapters (named "Motor control PWM", perhaps), print the pages describing the control registers or create a table of register bits (if anything isn't clear, you could ask here), get an oscilloscope, and write and run short test programs intended to generate just PWM signals.
Later on, you can integrate your working configuration sequence into your MPPT program.
I'd suggest to start with Microchip's AN1338, although this one is for a dsPIC33F. Using the datasheet of the EP (yes - there's more available than some "product brief"), it shouldn't be too difficult to port this to the dsPIC33EP.
Product page: https://www.microchip.com/wwwproducts/en/dsPIC33EP16GS502
An alternative might be to use Microchip's MCC tool, although it might not be free from errors. But it's worth a try.
The "standard development" for dsPICs is MPLAB X + the XC16 compiler, MCC (and some more packages) comes as an addon.
In case of "issues", there's support available via https://microchipdeveloper.com/ as well as via the Microchip forums...
Dear Gokhan,
In my opinion, do not use CSS but the free XC16 compiler provided by Microchip.
With the XC16 you can set the various register values directly without the need to use and remember all this CSS functions.
You can use MPLAB X IDE to develop your code and embed XC16 in it to compile it.
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