28128 Parallax Inc, 28128 Datasheet - Page 115

• 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

Questions
Challenge!
1. What's the main difference between the Stamp-O-Scope display and a regular
2. If the frequency of a signal is 1000 Hz, what's the period?
3. How can you adjust the scale to display finer variations in voltage using the
4. How can you increase the refresh rate of the Stamp-O-Scope? Hint: examine the
1. Modify Program Listing 5.3 so that it plays two notes simultaneously. For a hint,
2. Modify Program Listing 5.1 and add a second lead that measures only 0 and 1
3. If you succeeded with Challenge #1, add a potentiometer to the Board of
4. A really cool thing to do would be to discover a phenomenon called phase shift.
oscilloscope display?
Stamp-O-Scope? Hint: The answer involves an adjustment to the PBASIC code
for Program Listing 5.1.
code again; what factor limits the speed at which the signal is measured?
look up the
Stamp Editor Help menu
logic levels. Modify the code to display voltage activity of this second lead and
the Stamp-O-Scope input simultaneously on the same display. Good luck!
Education and wire it as a voltage divider. Hook the new, second input lead to
the wiper terminal of the pot. Vary the pot above and below threshold voltage
and see if you can match the frequency of the triangle wave.
Connect the input lead of the second channel you developed in Challenge 2 to
the D/A converter output. Also, connect the channel 1 lead (ADC0831 Vin(+)) to
the D/A converter output. Adjust the D/A converter to up count and down count
between 4 and 15. Note that there's a delay between the mid point of the triangle
wave and the transition of the pulse train. Adjusting the lower limits of the
counting variables and notice that the delay shifts. This delay is called phase
shift.
FREQOUT
command in the BASIC Stamp Manual or the BASIC