27220 Parallax Inc, 27220 Datasheet - Page 116

• Manufacturer Part Number: 27220
• Description: BOOK STAMPWORKS
• Manufacturer: Parallax Inc

Specifications of 27220

• Accessory Type: Booklet
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• For Use With/related Products: StampWorks
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Not applicable / Not applicable

EXPERIMENT #17: ADVANCED FREQUENCY MEASUREMENT
This experiment demonstrates how the BASIC Stamp can measure the frequency of
an input signal by using the PULSIN function.
Look It Up: PBASIC Elements to Know
Building the Circuit
Use the same circuit as Experiment #16
Program: SW21-EX17-Freq_Measure-Adv.BS2
' {$STAMP BS2}
' {$PBASIC 2.5}
' -----[ Program Description ]---------------------------------------------
'
' This program monitors and displays the frequency of a signal on 15. The
' period of the input cycle is measured in two halves: low, then high.
' Frequency is calculated using the formula F = 1 / Period.
' -----[ I/O Definitions ]-------------------------------------------------
FreqIn
' -----[ Constants ]-------------------------------------------------------
Scale
' -----[ Variables ]-------------------------------------------------------
pHigh
pLow
period
freq
•
•
•
PULSIN
DEC (used with DEBUG)
CLREOL (used with DEBUG)
PIN
CON
VAR
VAR
VAR
VAR
15
$200
Word
Word
Word
Word
' frequency input pin
' 2.0 us per unit
' high pulse timing
' low pulse timing
' cycle time (high + low)
' frequency