I'm currently building a hygrometer (according to tutorials like this https://www.sweetpi.de/blog/436/luftfeuchtigkeit-und-temperatur-mit-dem-raspberry-pi-messen)

All tutorials are using the "normal" Pi. I use the RasPi Zero W. After 1,5 days trouble with this setup on Raspi zero, I tried the same on an old Raspi (the first Model-B which was released I think) and it works!

Now I'm searching for any differences between the Pi's? Hope one of you haves an idea.

3 Answers 3


There are differences.

The original Pi had a 26 pin expansion header while the Pi Zero has a 40 pin expansion header.

The original model B gives access to GPIO 0-1, 4, 7-11, 14-15, 17-18, 21-25.

The Pi Zero gives access to GPIO 0-27.

Different GPIO are attached to pins 3, 5, and 13.

Pin Orig Zero
3   0    2
5   1    3
13  21  27

There are small differences between the older 26 PIN and the newer 40 PIN headers (see https://elinux.org/RPi_Low-level_peripherals).

However the manual in your link uses GPIO 4, which did not change.

  • 1
    This answer mainly constitutes of a link. Would you put a summary of the important points in your answer?
    – Mast
    Commented Dec 10, 2017 at 22:26

All but the (very early) models A and B with the 26-pin connector (see here) share the identical 40-pin GPIO connector (see here) which includes the models A+, B+, Raspberry Pi 2 B, Raspberry Pi 3 B, Zero and Zero-W. Most tutorials however are based on those newer models. If in doubt make sure the double check.

Secondary functions (such as UART and I2C) might differ though, see here

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