PCB Assignment

PCB Assignment

(MAS863 F’03)

Schematic:

Library:

http://fab.media.mit.edu/topics/electronics/pcb/fab.lbr

contains: PIC16F876, oscillator, resistor, capacitor, switch, LED,
MAX202, DB9 connector, solder pads.

Discussion:

this board has a PIC16F876 that connects to the serial port of a PC.

the caveat is that the PIC puts out voltage levels of 0V when it wants

to transmit a 0, and 5V when it wants to transmit a 1. the serial port

of a PC (which is RS232), expects 15V for a 0, and -15V for 1 -- the

job of the MAX202 is to take the USART (the serial port) on the PIC,

and convert its voltage levels to something the computer can

understand. as you can see, the MAX202 is wired to something that

looks like a serial port connector.

the PIC also has pins 11 and 12 hooked to LEDs that we can control in

the software. LEDs are really good for debugging, and its also because

all circuit boards at the media lab need blinking lights to hypnotize

people with.

on pins 23 and 22 we are connecting to a bunch of programmable switches

so you can get input into your board. you will also notice there is a

switch connected to pin 1. that pin will let you reset your board.

pins 1, 22, and 23 are connected to a "program port" (along with

ground). this pin will allow us to upload and burn in new code into

the micro controller.

the only two things not in the library are power and ground --

those can be found in the supply1.lbr library that ships with eagle.

on most components, power and ground are labeled Vdd and Vss, respectively.

Additional Info:

The simulation tool that you can use with Eagle is ngspice,

You can export a SPICE netlist from Eagle with

There's a collection of SPICE examples at