I’d like to design and build my own custom Arduino mega 2560 PCB but before I do that I have some question about electronics components and some links in the board and I'm really interested to ask experience people like :blush: you in this forum… by the way
I read this article about make Arduino UNO http://www.buildcircuit.com/build-your-own-arduino-board/
also I read this one http://tsjwang.blogspot.com/2013/08/diy-arduino-mega-2560.html
as we see there are many components not used in the board because the remove USB port and ATMEL chip to programming Arduino via ISP
I'm interesting in this edition of Arduino mega 2560 http://www.elecfreaks.com/wiki/index.php?title=Freaduino_Mega2560 there is schematic for design
my questions are :disappointed_relieved: :-
Q1/ what’s difference between Regular Arduino MEGA 2560 and Freaduino_Mega2560 in components that’s make Freaduino_Mega2560 5V current 2A.
Q2/ how the select able switch between 5 and 3.3 v work, the mega have 3.3 v so why there is select able switch.
Q3/if I want to remove USB and FTDI chip from the design and programming the board via ISP pins, how many capacitor and resistor and other components from the schematic do I need to remove because I don’t need it.
Q4/ LDO Voltage Regulators NCP1117ST50T3G is this chip use to drop the input voltage from power jack from 9v to 5v to source all the board with mega2560 chip or not.
Q5/ why there is OP LMV358IDGKR and for what it use if I want to remove the USB do I need it or not.
Q6/FDN340P Fairchild Semiconductor what is this chip and if I want to remove the USB do I need it or not.
Q7/why there is another LP2985-33 Linear Regulator with different size and also if I want to remove the USB do I need it or not.
Q8/ as you see in this link http://www.elecfreaks.com/wiki/index.php?title=Freaduino_Mega2560
the Freaduino use DC/DC MP2307 while the original Arduino Mega 2560 don’t have this chip
Q9/ if I’ll remove the USB with ATMEL or FTDI do I need to use Two crystal 16mhz in the board or one will be enough?
I hope everyone have knowledge share it with me because me experience in electronic :'( circuits and PCB is poor.