PIC16F877A Based MPPT Project (Help)

Thread Starter

Hakimos

Joined Oct 14, 2014
16
Hello guys, i'm building a solar mppt charge controller (I'll implement Perturb and Observe algorithme on PIC16F877A). I've joined the schematic on PDF, can you tell me if my schematic is correct ? Thank you.
I've tested the buck alone, it worked, i've added a pwm from pic to my buck (controlled with pot) and it worked too. Current sensor worked too but sometimes I get some weird values.
I've never tested the whole circuit and that's why I'm here, I want to put all together on a PCB but i want to be sure that there is no mistake in my schematics.
thank you and have a good day
 

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ErnieM

Joined Apr 24, 2011
8,006
Starting at IC1: A capacitor (C9) makes a very bad choice to power a linear regulator.

If you add some connections to this part keep in mind you can't take power out of a part you need that same power to turn it on in the first place.
 

Thread Starter

Hakimos

Joined Oct 14, 2014
16
Thank you ErnieM, is this the only mistake you can see in my schematic ? All others parts are good ? Thank you.
 

ErnieM

Joined Apr 24, 2011
8,006
Only? I highly doubt that.

A typical PCB goes thru an average of between 2 and 3 respins before it works well enough for production. And that is after an initial breadboard.

You have a good start at a first cut here. You don't have a package ready to go to PCB layout as you still lack a complete bill of materials defining the specific part you will use. Example: the LM358 comes in about 9 different packages; the exact part number will indicate that.

I did note one other missing connection. To eliminate these stop using 4 way junctions in all cases. Make junctions at a T intersection and you will never miss a junction (or make one your design rules checker will miss).
 

Thread Starter

Hakimos

Joined Oct 14, 2014
16
Hello ErnieM. Thank you again for answering me.
I've already printed (at home with toner transfer method) a PCB containing this LM358 package and it perfectly fits.
For the junction, i use the "eye" (on top left near the "i") button and i check connection, it seems to be okay.
Thank you again.
 
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