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Arduinos & Breaduinos
SPI I/O Extension
Add extra uC I/O pins with 74HC595 and 74HC165
Extending the microcontroller digital IO pins with parallel/serial shift registers. Here we wil chain 2 output and one input register resulting in 16 extra output pins and 8 extra input pins.
More of this circuits can be chained to have even extra pins, with impact on performance of course.
SPI is a full-duplex bus, so we read and write the data simultaneously.
Wiring
The base schema
Using with a breaduino
On this video we will use the extension with virtual pins software to make it easier to code, also we are using another input shift register, but the principle remains.
VirtualPins are open source (see side link) and are under test.
