Schematic Diagrams
Microcomputer Architecture and Interfacing
Colorado School of Mines
Professor William Hoff
1
Schematic diagrams
• A schematic (or circuit)
diagram uses standard
graphic symbols rather than
realistic pictures
– Omits details that are not
relevant to the design
From:
http://en.wikipedia.org/wiki
/Circuit_diagram
Microcomputer Architecture and Interfacing
Colorado School of Mines
Professor William Hoff
2
Mechanical layout diagram
• This is an
additional
drawing that
helps to
locate the
physical parts
• But it doesn’t
describe the
functionality
From: SSMI board datasheet
Microcomputer Architecture and Interfacing
Colorado School of Mines
Professor William Hoff
3
Software drawing tools
• Eagle Schematic Capture from CadSoft
– freeware from www.cadsoftusa.com
• CircuitLab
– Basic but easy to use
– Since it is on the web, it is available anywhere without an install
– https://www.circuitlab.com/editor/
• Microsoft Visio
– Students can download Visio for free through the CSM website
– It has many drawing capabilities in addition to circuit diagrams
– http://inside.mines.edu/CCIT-dreamspark
• MS Word or PowerPoint are ok for simple circuits
Microcomputer Architecture and Interfacing
Colorado School of Mines
Professor William Hoff
4
Standard Symbols – discrete components
AC
source
+
R
R
L
potentiometer
fixed
resistor
C
unpolarized
capacitor
inductors
S
G
P-channel
PNP
SPST
battery
push button
D
G
N-channel
S
D
photo
Transistor
NPN
VDDA
LED
-
D
ZENER
D
power & ground symbols
op amp or comparator
VDD
+
from http://www.eehomepage.com/symbols.ppt
Microcomputer Architecture and Interfacing
Colorado School of Mines
Professor William Hoff
5
IC Components
• Integrated circuit chip components
Example from SSMI board schematic
– Draw as a rectangle
– Label signals (inside rectangle)
• Don’t need to draw unused signals
– Label pin numbers (outside
rectangle)
– Label part name
– Label “unit number” (Uxx)
• To clean up diagrams
– Avoid drawing long runs by labeling
signals and using connector symbols
– E.g., don’t show all Vcc and grounds
connected together
Microcomputer Architecture and Interfacing
Colorado School of Mines
Professor William Hoff
6
Examples
• SSMI board
schematic
• Nanocore
schematic
(shown)
• Also
examples in
the
textbook
Microcomputer Architecture and Interfacing
Colorado School of Mines
Professor William Hoff
7