28119 Parallax Inc, 28119 Datasheet - Page 39

• Manufacturer Part Number: 28119
• Description: KIT UNDERSTANDING SIGNALS
• Manufacturer: Parallax Inc

Specifications of 28119

• Lead Free Status: Contains lead
• Accessory Type: Oscilloscope
• Interface Type: USB
• For Use With/related Products: BASIC Stamp® 2 and Board of Education
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

ACTIVITY #2: MEASURING TIME-VARYING SERVO PULSES
Use the same parts and circuitry as the previous activity. No changes to the OPTAscope
settings are required.
Time-Varying Pulse Widths with the ServoSweep.bs2 Program
' Understanding Signals - ServoSweep.bs2
' Demonstrate a changing servo pulse
' {$STAMP BS2}
' {$PBASIC 2.5}
PulseWidth
Counter
√
√
√
√
Run the program ServoSweep.bs2, which will vary the pulse width.
Press the Run / Stop button when the pulse is at its widest.
Measure the pulse width using the Vertical Bars cursor setting.
Repeat this process to measure the pulse at its narrowest extreme.
Are your measurements different? Calibrate! If your measurements vary from those in
the text, you may try calibrating your OPTAscope to see if that is the source of the
discrepancy. To begin, disconnect all probes from your circuit. Then select Calibrate from
the File drop-down menu on the OPTAscope task bar, and follow the directions.
VAR
VAR
Word
Word
' Pulse length
' Pulse counter
Figure 2-9:
The delta
symbol ∆
shows a pulse
width of 1.500
ms.