122-28029 Parallax Inc, 122-28029 Datasheet - Page 262

• Manufacturer Part Number: 122-28029
• Description: GUIDE STUDENT SMART SENSORS
• Manufacturer: Parallax Inc

Specifications of 122-28029

• Accessory Type: Manual
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: Smart Sensors
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Contains lead / RoHS non-compliant

Page 250 · Smart Sensors and Applications
LOOP
Datalogging Various Operating Conditions
It might seem at this point like the application is ready for some code that converts
revolutions to distance, and maybe an LCD display and a couple of buttons for selecting
LCD menu items. The problem here is we only examined the wheel turning two speeds.
What about when the rider is leaning into sharp turns – does the acceleration change
then? What about in cold and hot temperatures – will they cause the measurements to be
different? It certainly wouldn't do to have a product on the market that only tracked
bicycle distance some of the time. The product would get a bad reputation very quickly.
Figure 6-19 shows a datalogged acceleration study for the bicycle at two slightly different
speeds. The area around 400 ms is where the wheel was slowed down. The important
thing to note from this graph is the offset of the x and y-axis measurements. At the
higher speed, the y-axis signal varied between 1 and −0.5 g while the x-axis
measurements varied between −1.5 and 0.25 g. After slowing the wheel down, the y-axis
measurement varied between 1 and -1 g, while the x-axis measurement varied between
about 0.7 and −1.3 g.
Figure 6-19 is just a graph of two different speeds. True, the hysteresis code from
TestWheelCounter.bs2 works under both of these conditions, but does it work under ALL
conditions? With this kind of question, engineers might apply a few equations to predict
the accelerations under various extreme conditions that they anticipate. Simulation
software could also be used to verify the outcomes. Even if this kind of expertise is
available, the product still has to be tested in a variety of "real life" conditions, especially
to rule out the possibility of incorrect assumptions on the part of the engineers. That's
where datalogging comes back into the picture. The actual prototype still has to be taken
through the various conditions that it might experience on anybody's bicycle before it is
safe to make the investment in the plastic case, a refined electronic design that features
low cost parts, mass production and inventory costs.
DO UNTIL y < 2350
LOOP
counter = counter + 1
FREQOUT 4, 200, 3750
PULSIN 7, 1, y