GPIO Inputs and Outputs - an intermediate guide for Arduino and ESP projects

This is the first in a series of intermediate electronics tutorials for Arduino and ESP8266/ESP32 projects. In this video, I'll be covering General Purpose Input and Outputs (GPIO) - which are the essential component through which your microprocessor interacts with the outside world.

Topics covered include digital/analog inputs and outputs, logic levels, floating inputs, pullup/pulldown resistors, PWM, ADC, high current applications, and port expanders.

I'll be illustrating two practical examples of components that typically use a lot of GPIOs - an LCD display output, and a matrix keypad input, and how you can use a port expander such as a PCF8574 or MCP23017 to connect both these devices (and many more!) using only two GPIO pins on your microprocessor, via an I2C interface.

00:00:00 - 00:02:57 Introduction
00:02:58 - 00:03:29 GPIO pins
00:03:30 - 00:05:35 Digital I/O with HIGH and LOW logic
00:05:36 - 00:09:02 Floating Inputs, PULL-UP and PULL-DOWN resistors
00:09:03 - 00:12:36 Digital Outputs and 3.3V/5V logic levels
00:12:37 - 00:14:30 Controlling High Current Output using transistors
00:14:31 - 00:16:27 Analog Output using PWM
00:16:28 - 00:17:41 Analog Inputs using ADC
00:17:42 - 00:19:39 GPIO pin availability and port expanders
00:19:40 - 00:21:29 GPIO hungry components: LCDs and Keypads
00:21:30 - 00:29:10 PCF8574 Port Expander Demo
00:29:11 - 00:40:08 Arduino Code
00:40:09 - 00:43:08 Alternative Port Expanders: MCP23017 (I2C) / MCPS17 (SPI)
00:43:09 - 00:43:59 Wrapup

Thanks you for providing information for intermediates. Past the beginner level, it's get quite hard to find good quality information like your video.

[viewtorelax]

clear and nicely explained, subscribed, keep up the good work bro.. )

[andrewsturridge]

Thank you, this is just what I needed for my current level of working with electronics

[substandard]

This was an excellent primer, ta very much

[neoflix]

Love your ideas and projects and a nice easy approach to explaining with great presentations

[JeffTheFlame]

Really good explanations saving a bunch of time for beginners and intermediates. Thank you

[nicholasleluan]

The timing of this video was absolutely perfect. I have been struggling with interfacing NRF24L01 and RC522 with UNO over SPI. Particularly selecting an external power supply to power the NRF and/or RC522.
Looking forward to more videos like this in the future.

[robertedlund]

Absolutely perfect fit for what I may require soon ! Mega thanks!

[nkbdl]

Thank you for the vid. It was really informative and just what I wanted. Something more intermediate. Logic wise, you mentioned you don't want the keys to be pressed continuously, but what if there is an input say, piggy where the "g" is repeated? Perhaps you put a 1 second pause before accepting a "repeated" press input?

Anyways thank you. I was actually looking for a video where I can connect a RGB screen and an input device of a few buttons. This came really close to what I need!

[markgriffin]

I love this video, it was really helpful in explaining what these I2C pins were for (I've seen them on pinout diagrams before, but didn't know how to use them), and would love for other videos about different protocols. The other thing I always struggle with (though maybe it's just me) is the actual physical wiring of my projects. I can solder things just fine, but I don't own that many components and frequently want to reuse them. So what kind of connectors can I use and which wires (gage, core etc.) go with them? I have failed a few attempts to install wires into those black connectors that you're using to connect the I2C pins to that first port expander. Thanks for the great content!

[B_mata]

Thanks for this video Alistair. Looking at the PCF8574 module, I see that there are pull-up resistors on the I2C pins. If one is chaining multiple modules, I think it would be wise to remove the pull-up resistors on all but the first module. Otherwise, all the pull-ups will be in parallel and that could drain too much current. What do you think?

[abuzzakasm]

Can you make a video on esp 32 wich is control by unity editor