Sometimes the best way to truly understand your microcontroller is to take away the comfort of built-in hardware and do things by hand. That’s exactly what Curious Scientist demonstrates in their excellent tutorial.
In that post, you’ll see how to build an I²C implementation entirely in software to drive an SSD1306 OLED display. It’s practical, easy to follow, and packed with the kind of insights you don’t get from just calling a library function. But before you dive into it, let’s take a step back and talk about bit-banging itself—why it exists, why it’s still useful, and what you gain from learning it.
What Bit-Banging Really Means
Bit-banging is the art of using software to manually toggle GPIO pins in order to mimic a communication protocol. Instead of letting a dedicated hardware peripheral generate the waveforms for you, the CPU itself steps in, setting pins high and low at just the right times to simulate the protocol’s rules. In practice, it’s a bit like teaching your microcontroller to “speak” a language it wasn’t born with.
Why Engineers Still Use It
You might wonder why anyone would bother when hardware peripherals are faster, more efficient, and already built into most chips. The truth is, bit-banging is incredibly valuable in certain situations. If your microcontroller doesn’t support a protocol, you can simply emulate it in software. If you want to deeply understand how signals behave on the wire, bit-banging forces you to engage with the timing and logic that usually stay hidden. It’s also a lifesaver in debugging, where the flexibility to bend protocol rules or slow things down makes stubborn devices easier to handle. And in early bootloaders or lightweight applications, it’s often simpler to toggle pins directly rather than initializing entire subsystems.
The Limitations
Of course, bit-banging has its drawbacks. Since the CPU is responsible for every pin change, timing can be fragile and prone to disruption if an interrupt occurs at the wrong moment. It consumes more processing power and energy, because the core is constantly busy “faking” the protocol. Speeds are also limited—while hardware I²C can handle hundreds of kilohertz or even several megahertz, bit-banged implementations usually run much slower. Yet for small displays, low-speed sensors, and experimental setups, those trade-offs are well worth it.
Beyond I²C
Curious Scientist’s tutorial focuses on an OLED display with I²C, but the concept of bit-banging goes much further. Many engineers have used it to emulate SPI for sensors and flash chips, to communicate with Dallas/Maxim 1-Wire temperature sensors, or to implement custom protocols that no hardware peripheral could support. Even things like infrared communication with remotes often rely on carefully timed GPIO toggling. Once you understand the principle, the possibilities are wide open.
Why You Should Read the Curious Scientist’s Tutorial
What makes the tutorial so valuable is the way it connects theory with practice. It doesn’t just explain the abstract concept of bit-banging—it shows you how to implement start and stop conditions, handle acknowledgments, and actually send characters to an SSD1306 display. By the time you finish, you won’t just have text showing up on an OLED screen; you’ll also have a deeper appreciation for what’s happening on the wire every time you connect a sensor or display.
