28128 Parallax Inc, 28128 Datasheet - Page 108

• Manufacturer Part Number: 28128
• Description: KIT BASIC ANALOG/DIGI PARTS ONLY
• Manufacturer: Parallax Inc

Specifications of 28128

• Accessory Type: ADC, DAC
• Product: Microcontroller Accessories
• For Use With/related Products: BASIC Stamp® 2 and Board of Education
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

value of
values of
has to be between 0 and 15.
Changing the limits of the first
stays high. In other words, you can change the pulse width buy adjusting the
and
FOR…NEXT
By changing both the duration of the low and high portion of the signal proportionately,
you can change the frequency without affecting the duty cycle. By changing only one of
the two sets of limits, you change the duty cycle as well as the frequency of the signal.
Now let's run the frequency of this pulse train up into the audible sound frequency range
and listen to the result of adjusting these signal characteristics. Remove the ADC0831
from the circuit. Also, replace the LED circuit with the piezoelectric speaker circuit
shown in Figure 5-5.
EndValue
n
n
Pulse width: A pulse train goes high-low-high-low-high-low... the pulse width is the amount
of time that a pulse train stays high in between the lows
Duty cycle: The duty cycle is the ratio of time the signal stays high to the amount of time it
takes the signal to repeat itself. In other words it's the pulse width divided by the period of
the signal.
loop adjusts the duration of the low portion of the signal.
in the second
in the first
arguments of the
FOR…NEXT
FOR…NEXT
FOR…NEXT
FOR…NEXT
loop to change the amplitude. You can change the
loop to get various DC offsets. Just remember that
loop. Changing these values in the second
loop changes the amount of time the signal
StartValue
n