122-28176 Parallax Inc, 122-28176 Datasheet - Page 124

• Manufacturer Part Number: 122-28176
• Description: GUIDE STUDENT PROCESS CONTROL
• Manufacturer: Parallax Inc

Specifications of 122-28176

• Accessory Type: Manual
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: Propeller Education (PE) Kit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Contains lead / RoHS non-compliant

Challenge 4-5: Debounce with Programming
ACTIVITY #6: TACHOMETER – HIGH-SPEED COUNTING
Many processes, such as measuring the revolutions of a shaft, must employ high speed
counting. A tachometer measures the number of shaft rotations per unit time. Other
examples include measuring the revolutions per minute (RPM) of engines, motors,
generators, cutting drills, and CD ROMS.
A tachometer uses input pulses to calculate the RPM. Pulses may be obtained through
various methods, including detecting light reflection, using magnetic sensors or having a
coupled DC generator provide an analog output.
In this activity, the RPM of a fan will be measured by counting the number of encoder
wheel reflections per unit time. As the fan spins, the light from the LED emitter will be
reflected to the detector (white segment) or absorbed (black segment). This will provide
a pulse stream into the BASIC Stamp. By counting the transitions, the fan's RPM can be
calculated.
The PBASIC
and then store the value in a variable:
...where
The count results will be stored in the
√
√
Save BoxConveyor.bs2 under a new name.
To the
affecting the count for normal conditions. Pseudocode is provided for one
method. Show your code and indicate your results.
Detect box.
Pause appropriate time.
Check box again.
If still detected, set the flag.
COUNT Pin, Duration, Variable
Duration
COUNT
Count_Box
is the time during wthch to count, in 1 ms units for the BASIC Stamp 2.
instruction is used to count the number of pulses for a given time
subroutine add code that would prevent input bounce from
Variable
specified.