28029 Parallax Inc, 28029 Datasheet - Page 186

• Manufacturer Part Number: 28029
• Description: KIT PARTS SMART SENSORS W/TEXT
• Manufacturer: Parallax Inc

Specifications of 28029

• Accessory Type: Parts Kit
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: BASIC Stamp® or Javelin Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Contains lead / RoHS non-compliant
• Other names: 28029PAR

Page 174 · Smart Sensors and Applications
Algebra to Determine Scale and Offset
The XY plot displayed in the Debug Terminal in this activity is called the Cartesian
coordinate system. Named after 17
is the basis for graphing techniques used in many mathematical pursuits. Shown in
Figure 5-4a, the Cartesian coordinate system is most commonly displayed with (0, 0) in
the center of the graph. Its values get larger going upward (y-axis) and to the right (x-
axis). Many displays behave differently, with coordinate 0, 0 starting at the top-left as in
Figure 5-4b. While the x-axis increases toward the right, the y-axis increases downward.
Figure 5-4: Cartesian vs. Display Coordinates
√
DEBUG CRSRXY, x, y, "*"
ENDIF
DEBUG CRSRXY, 0, 10, "Press any Key..."
DEBUGIN temp
Verify that this program does not allow you to enter characters outside the range
of -3 to 3.
a. Cartesian Coordinates
What about negative numbers?
The conditions for the IF...THEN statement in your modified version of PlotXYGraph.bs2
are (x > 12) OR (y > 6). This covers positive numbers that are larger than 12 or 6, but it also
covers all negative numbers. That's because the BASIC Stamp uses a system called two’s
complement to store negative numbers. In two’s complement, the unsigned version of any
negative value is larger than any positive value. For example, -1 is 65535, -2 is 65534, and
so on, down to -32768, which is actually 32768. Signed positive values only range from 1 to
32767.
th
century mathematician René Descartes, this system
b. Display Coordinates
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