I have a project where I use pins of PCF8574 expander placed on a breadboard and which is connected to Raspberry Pi. Pins of the expander should be connected forward to the ones of STM8 microcontroller(didn't find it for this schema).I have to introduce some resistors before I connect them, but I am a beginner and I want to know if this is the correct way to put the resistors between pins of the two devices ? Or I should do it another way? enter image description here

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    no ... the two leads of the resistor are shorted together ... investigate how a breadboard is constructed
    – jsotola
    Commented May 21, 2021 at 20:59

1 Answer 1


It appears you have shorted the two ends of the resistor - this is not what you want to do.

Breadboards (a.k.a. "solderless breadboards") are really simple, but like all simple things, you must invest some effort to understand how they are constructed. That means you'll need to know that the breadboard is actually just a series of metal clips (similar to the one shown below) covered with a plastic body which holds all these clips in the proper position, and provides a matrix of holes which wires and component leads pass through to make contact with the metal clips.

From what you've shown in your question, it appears your resistor leads connect into two different slots of the same clip; i.e. the resistor leads are shorted.

breadboard clips

I think if you'll try this search, you'll find several reasonably good explanations on how breadboards are built.

Breadboards were originally built in this way to support a specific type of packaging for integrated circuits - the Dual Inline Package (DIP) shown below. At one time, DIP was used almost exclusively for ICs; one of the "legs" was inserted into one of the clips; another leg was inserted in another clip.


Since the advent of surface mount technology, DIPs are no longer the standard package for ICs. But the industry has adapted, and now companies such as Adafruit and others manufacture and sell surface mount ICs mounted on "Breakout Boards". These breakout boards are now compatible with the solderless breadboard.

  • Thanks for your answer, I read about the breadboard a bit and I am thinking that the right way would be something like this ? One terminal connected to digital pin and another one to ground ? ibb.co/3fSzw4Z I would appreciate if someone would let me know Commented May 26, 2021 at 14:05
  • @GabrielTătărușanu: Yes - that's more like it :)
    – Seamus
    Commented May 26, 2021 at 15:20
  • @GabrielTătărușanu: I have just run across this "Guide To Solderless Breadboards", and thought it might be of interest. And here's another article of interest as it discusses some limitations of solderless breadboards
    – Seamus
    Commented Jun 8, 2021 at 23:56

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