Please can someone explain this code to me:

TRISA = 0x000C; //sets pins RA2 and RA3 to inputs, rest of PortA as outputs
TRISC = 0xA000; //sets pins RC13 and RC15 as inputs, all else as outputs

I do not understand how 0x000C represents pins RA2 and RA3 ...and how 0xA000 represents pins RC13 and RC15. I understand binary numbers and a bit of hexadecimal but the above code throws me off.

Help!

 

0x000C=00000000000000000000000000001100 binary with the 32bit compiler.

A TRIS bit set to 1 is a input: RA2 and RA3
the rest of the bits are all 0 in a 32 bit TRIS register for outputs

Section 12.2
http://ww1.microchip.com/downloads/en/DeviceDoc/61120D.pdf

 

As nsaspook said, you need to write out the whole 32 bit number in binary.

I like to see the bit numbers (RA2 or RC15), so I will write them down to construct the binary number. That was lots easier with 8 bit processors, but you can still do it with long words if you write the bit number vertically:

3322 2222 2222 1111 1111 11
1098 7654 3210 9876 5432 1098 7654 3210
----.----.----.----.----.----.----.----
0000 0000 0000 0000 0000 0000 0000 1100
   0    0    0    0    0    0    0    C = 0x 0000 000C

3322 2222 2222 1111 1111 11
1098 7654 3210 9876 5432 1098 7654 3210
----.----.----.----.----.----.----.----
0000 0000 0000 0000 1100 0000 0000 0000
   0    0    0    0    A    0    0    0 = 0x 0000 A000

It also helps to separate the bits into hex digits. When I'm doing this a lot I can look at the binary and write the hex digit.

As a final note, a 32 bit quantity needs a full 8 hex digits to fully specify it.

 

nsaspook and ErnieM:

Thank you so much for the explanation, I now fully understand....I spent over week trying to grab that piece of code but you guys broke it down to me in minutes.

I have another question but it has to do with setting up the software and complier on my laptop.

I got the PIC32MX795F512L USB starter kit, the I/O expansion board and the cable from the starter kit to a USB port on my laptop. Do I still need the Explorer 16 development board (DM240001) and the MPLAB REAL ICE in-circuit debugger (DV244005)....?

 

I got the PIC32MX795F512L USB starter kit, the I/O expansion board and the cable from the starter kit to a USB port on my laptop. Do I still need the Explorer 16 development board (DM240001) and the MPLAB REAL ICE in-circuit debugger (DV244005)....?

No and no. The Explorer 16 is a different system where you can change out processors. The USB starter kit has a fixed processor along with a 2nd processor to handle programming and debugging, which means you don't need a separate (ICE) debugger either.

I'm sure that kit comes with some tutorials. Crack them open and try out the first one.

 

Thanks ErnieM!