28128 Parallax Inc, 28128 Datasheet - Page 78

• 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

Page 68 · Basic Analog and Digital
Stamp to send the resistive ladder network sets of binary voltage levels. These sets of
binary voltages are converted by the resistive ladder network to discrete output voltages.
The DVM from Chapter #3 will be used to measure the converter's output voltages.
Measuring all the D/A converter's output levels is called a voltage sweep. We will use
PBASIC to automate our DVM to perform the entire voltage sweep. That way, the D/A
converter's output voltages can be measured without manually repeating each
measurement.
Parts Required
Gather these parts from your parts kit and let's get started:
(6) 2 k resistors
(3) 1 k resistors
(1) ADC0831 A/D Converter
(1) Red LED
(1) 270
resistor
(1) LM 358 op-amp
The resistive ladder network for this experiment is shown in shown in Figure 4-1. The
name comes from the fact that the resistor network in the schematic resembles a ladder.
It's definitely an inexpensive alternative compared to an integrated circuit digital to
analog converter (D/A converter or DAC). A few resistors are a fraction of the cost of an
integrated circuit.