27220 Parallax Inc, 27220 Datasheet - Page 149

• Manufacturer Part Number: 27220
• Description: BOOK STAMPWORKS
• Manufacturer: Parallax Inc

Specifications of 27220

• Accessory Type: Booklet
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• For Use With/related Products: StampWorks
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Not applicable / Not applicable

Moving Forward · Page 139
Behind the Scenes
The experiment demonstrates SHIFTIN, the complementary function to SHIFTOUT.
In this case, three BASIC Stamp I/O pins are used to read the state of eight DIP
switches. To read the data from the 74HC165, the parallel inputs are latched by
briefly pulsing the Load line (high-low-high), then using SHIFTIN to move the data
into the BASIC Stamp.
Note that the DIP-switches are pulled-up to Vdd, so setting them to the closed
position puts a logic low (0) on the shift register inputs. By using the Q\ (inverted
Data Out) pin from the 74HC165, the switch data arrives at the BASIC Stamp with
"1" bit indicating that a switch is closed.
Taking it Further
As with the 74HC595, we can cascade the 74HC165 to create more inputs with the
same three I/O pins. Connect your choice of inputs to the circuit below: