Hello everyone,
I'm looking for a pin expansion board for Arduino UNO, anyone has any idea for what should I choose in order to expand the number of pins?
Thank you in advance.
You can use Arduino MEGA.
The Arduino Mega 2560 is a microcontroller board based on the ATmega2560.
It has 54 digital input/output pins (of which 15 can be used as PWM outputs),
16 analog inputs, 4 UARTs (hardware serial ports), a 16 MHz crystal oscillator,
a USB connection, a power jack, an ICSP header, and a reset button.
this is not an installation question... I moved your post to a more suitable location
Do yourself a favour and please read How to get the best out of this forum and post accordingly (including code tags and necessary documentation for your ask when appropriate).
to your question you can probably read this (google translated) blog post
you'll see there is a solid list of options
How about a pin expansion board?
(Note: that is a link!)
And using a Nano rather than a UNO would be more practical.
Mega 2560 with Terminal shield 54 D's, 16 AI's, 4 UARTS, SDI/SLC. Mega is ~$20USD and the terminal shield is another $20USD.
Do you mean having more Input/Outputs or having more physical access as with a breadboard.
Thank you all for your suggestions.
I purchased an Arduino Mega to use it instead of Arduino Uno.
And if the number of pins are not sufficient, I'll use the Module PCF8575, or the Terminal shield 54 D's and follow the guide provided by J-M-L .
Do you mean having more Input/Outputs or having more physical access as with a breadboard.
I actually need more GND pins and more pins for UART communication.
Thank you again.
You can get some ideas from the following links:
For that, you can simply use stripboard
are you saying you want to use many software serial instances over a port extension? that likely won't work...
Wagos work well for tinkering 
gnd and power pins are in short supply because the Arduinos are not power supplies. Those +5 pins are for INPUT!
Use solderable buss bars for reliable power connections.
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They are on the OUTPUT! of a regulator.
the doc states (for a UNO)
- 5V.This pin outputs a regulated 5V from the regulator on the board. The board can be supplied with power either from the DC power jack (7 - 12V), the USB connector (5V), or the VIN pin of the board (7-12V). Supplying voltage via the 5V or 3.3V pins bypasses the regulator, and can damage your board. We don't advise it.
No, both the pins and the regulator share a common buss internally. The reg on the Arduino powers ONLY the Arduino. Use a nice SOLID +5 coming IN on the +5 pin and ignore the regulator.
That cannot be correct as it implies the board cannot be fed +5 directly and yet the USB does exactly that and bypasses the regulator. The buss doesn't know (or care) where the +5 is coming from, the reg, the USB or the +5 pin is all the same.
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Sorry, it's there to be used.
If you don't like that, that's fine.
The use is limited to what it can DRIVE. How many projects here have power issues because someone overloads the 200mA board max or the 40mA pin max, or the temp limits on the reg.
The +5 out is for nothing more than a test or few LED's. You want servos or rf or banks of relays you gotta have external power from somewhere.
If you're going to install it without a PC attached full time you need power. A phone charger, while nominally rated to either 1/2A or 2A, are notoriously "soft" (poorly regulated) and will cause issues with certain devices.
Since the card can't supply the rest of the project then you need TWO power supplies, one 7-12v for the barrel connection and a separate +5 for everything else. How much more elegant to run everything off one, solid +5v and be done with all of the issues? I use medical grade UL approved supplies for safety.
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Those work for test but come loose with vibration. Noisy power ruins performance and is hard to troubleshoot.
non sequitur