Hello, all. Please take a look at this example schematic:


The chip in question is the PIC18F4550 and as you can see power is provided on both sides (with a 100nF cap to smooth noise I guess). Is this strictly required or could you put power into one side and just ignore the other? I know that I have just put power in one side and everything still seems to work fine but I feel uneasy with doing that. I feel that they would not waste pins that could be doing something useful by having an extra pair of power in/out pins.

So my question, at its heart is: for what purpose does this PIC MCU (and others like it) have multiple power pins? Thanks in advance.

Mod note: removed spammy link and banned user, but retained this thread since responses are kind of useful.
olaf123 wrote:
So my question, at its heart is: for what purpose does this PIC MCU (and others like it) have multiple power pins? Thanks in advance.
It's usually to ensure the current requirements can be met with respect to current capacity of per-pin connections.

As an extreme example, consider a high-power Intel processor (section 7.9), which can draw more than 100A. In the documented 2011-pin socket, there are hundreds of pins allocated to power (section 8) just to satisfy the machine's needs.

You'll often see systems with separate analog and digital grounds, too. The point there is to isolate the analog components from digital noise (which requires careful board-level design).
I've had issues when getting a USB HID up and running with the PIC18F4550 without both VDD/VSS and as Tari suggested you will likely require it if you want to connect anything else to the MCU.

This is the basic circuit that I used (I think):



I did connect an ICSP header as well as per your circuit.

What are you building?
  
Register to Join the Conversation
Have your own thoughts to add to this or any other topic? Want to ask a question, offer a suggestion, share your own programs and projects, upload a file to the file archives, get help with calculator and computer programming, or simply chat with like-minded coders and tech and calculator enthusiasts via the site-wide AJAX SAX widget? Registration for a free Cemetech account only takes a minute.

» Go to Registration page
Page 1 of 1
» All times are UTC - 5 Hours
 
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum

 

Advertisement