Rate the eM8
By Fred Eady
Schematic diagrams are nice to have as they can convey the inner workings
of a design with just a glance. When it comes to totally understanding an alien
project, source code and a schematic are the ideal combination. A schematic
diagram without source code is useless if you are attempting to port or revive
the look and feel of the original application. However, it is a no-brainer to
recompile the source code and reload the target hardware without the help of
a schematic. What if you were presented with a piece of hardware, with no
accompanying schematic and source code, written totally in assembler? Could
you port the source code to C and retain the original look and feel of the
assembler-based application?
The Hardware
The eM8 (pronounced eMate) hardware captured in
Photo 1 comes from the land down under and was created
by Sam Wallace and Duncan Campbell as a teaching tool
for students attending the Queensland University of
Technology which is located in Brisbane, Australia.
Commercial use of the eM8 is discouraged as the design
contains digital and analog circuitry that is solely intended
to illustrate basic microcontroller concepts in a classroom
environment.
A Microchip PIC16F882 is the center of attraction, and
costars with a Microchip MCP2200 USB-to-Serial bridge and
a quartet of Kingbright ACSC04-41SURKWA-F01 Hyper Red
seven-segment display modules. If you’re new to the
MCP2200, we discussed the design details behind it in the
July ‘ 10 Design Cycle column over in Nuts & Volts. So far,
by simply attaching a USB cable between the eM8 and my
laptop, I’ve determined that the MCP2200 portal does not
use the USB interface as a source of power. That means the
MCP2200 is most likely used as a simple serial
communications portal.
The four Kingbright seven-segment displays are driven
in the traditional manner using an
41SURKWA-F01 LED display is a common
PHOTO 1. The eM8 looks really busy in
this shot. It’s not as daunting if you divide the
electronic functions at the printed circuit
board break-away points. From left to right,
Photo 1 reveals an I/O section, a main
computing and power section, and an LED
display section.
SERVO 11.2010 51
