28176 Parallax Inc, 28176 Datasheet - Page 115

• Manufacturer Part Number: 28176
• Description: KIT PARTS PROCESS CONTROL W/TEXT
• Manufacturer: Parallax Inc

Specifications of 28176

• Accessory Type: Process Control
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: BASIC Stamp® 2 and Board of Education
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Contains lead / RoHS non-compliant

program count every sample if a low level is sensed, as depicted by the partial flowchart
in Figure 4-15 (a)?
"Sample Time" is how frequently a program reads a value. If the sample time were
100 ms and the box was present for 2 seconds, how many counts would have occurred?
The algorithm would have counted 20 boxes! So the count cannot be based on whether
the object is detected or not. The count needs to occur only once: either at the first
detection of a box or when the box passes. A count needs to occur on the transition from
HIGH to LOW or LOW to HIGH. In digital terms, this is known as "Edge Triggering".
Figure 4-15 Detection and Counting Algorithms
a.
c.
b.