28128 Parallax Inc, 28128 Datasheet - Page 43

• 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

Press and hold the right button, then press and release the left button twice. Then the
output should look like Figure 2-7.
If your program worked as shown, you just synchronously shifted 4 serial bits into the
BASIC Stamp's RAM. In addition, it was verified that the decimal value of binary-1011
really is 11 in the decimal number system.
Figure 2-8 shows how these events occurred (from left to right) in a timing diagram. The
left pushbutton was the clock signal. The clock signal consisted of a series of clock
pulses. Each clock pulse was the press and release of the left pushbutton. This sent a low-
high-low signal to P1. Each time the left pushbutton was released, the BASIC Stamp
checked the state of the data line, which was the state of the right pushbutton (P0). The
BASIC Stamp is programmed to read the input data after the clock signal's transition
from high to low. This transition is referred to as the negative edge of the clock pulse.
Figure 2-7
Debug Terminal
Output for Program
Listing 2.2.