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Congrats! You can use it as output to send 8 bits of data in parallel to a sensor, but I don't know of many sensors like that. You could use it to drive a seven segment display, for example. I don't remember what chip I used in this example, but some shift registers have an output enable (usually active low). You could set the output enable to not send output to the pins, shift in the data, then set the output enable to send the data to the pins. Presto, you've got a digit on a seven segment display.
Thanks!By "cost wise" do you mean actual cost ($$$) or program size wise?Money-wise, the chips are cheap, even with shipping, so yes, they pay off.In terms of program size, I would say they do as well. I'm working on a library to make using them even easier, and I think it takes 5% of the program space on the Arduino Uno.But I guess program size doesn't really matter if your application needs those extra GPIOs. I'm building a project based on the ESP8266, and it only has 11 pins. I need 8 for a keypad, 7 for an LCD, and then I need the four used in SPI for an SD card. I have to expand the GPIO count, and I'll be using SPI anyway, so this just makes sense. I'm also looking at the MCP23S17, which is a 16 GPIO version of this. I think it will be much the same.
MCP23S08 With ArduinoView Instructable »
I already have this cube, and built it a while ago, so I went right to the part about programming it.I tried following the link to the software required to program it, and two things happened. First, I was warned that it was a harmful website containing malicious software. Then, when I decided to give it a go anyway, the file wasn't found. So I can't download it anyway. I tried the links in the theory and the links in the github (I think they are the same, but it's easy to click to be sure), and can't find the file.How am I supposed to program the cube if the software isn't available?
Google Home Light SwitchView Instructable »
Something like this would work, for typing in the number, but the rest of it would need to be coded, too, of course.
I don't think you can. The keyboard is part of the phone, so the circuitry to run the keyboard is in the phone. I wouldn't even know where to start.You can buy small bluetooth keyboards that work great with a raspberry pi. I'd look into those if I were you.
The code is mixed in with the text in Step 3