The ATtiny85, ATtiny88 and ATmega328P are all 8-bit AVR microcontrollers that can be used in Arduino-compatible projects. They are much smaller and simpler than modern 32-bit microcontrollers, but they are still useful when a project only needs basic control, a few inputs and outputs, or very low cost.
This article compares the ATtiny85, ATtiny88 and ATmega328P from a practical project point of view. The goal is not to find the most powerful chip, but to choose the right size of controller for the job.
Three Different Sizes of Classic AVR Controller
These three microcontrollers belong to the same general AVR family, but they are aimed at different project sizes.
- ATtiny85: very small controller for simple tasks
- ATtiny88: larger ATtiny device with more pins and more memory than ATtiny85
- ATmega328P: classic Arduino UNO / Nano / Pro Mini controller
The ATmega328P is the easiest choice for general Arduino projects. The ATtiny85 and ATtiny88 make sense when the project is simple enough that a full Arduino UNO-style controller would be larger or more expensive than needed.
ATtiny85: Very Small and Simple
The ATtiny85 is a tiny AVR microcontroller with limited memory and a small number of pins. It is popular for small embedded projects where only a few I/O lines are needed.
- 8-bit AVR microcontroller
- 8 KB flash memory
- 512 bytes SRAM
- 512 bytes EEPROM
- Small pin count
- Good for very simple control tasks
The ATtiny85 is useful for projects such as LED control, simple sensor reading, small timing circuits, button interfaces, tiny wearables and compact embedded modules. It is not a good choice when many pins, multiple communication interfaces or large libraries are required.
ATtiny88: More I/O Than ATtiny85
The ATtiny88 is still an ATtiny device, but it is much larger than the ATtiny85 in terms of available pins and general project flexibility. It can be useful when the ATtiny85 is too limited, but an ATmega328P board is still more than the project needs.
- 8-bit AVR microcontroller
- 8 KB flash memory
- 512 bytes SRAM
- 64 bytes EEPROM
- More I/O pins than ATtiny85
- Good for simple projects needing more connections
The ATtiny88 can be attractive for low-cost controller boards where pin count matters more than memory size. However, its limited memory still makes it less comfortable than an ATmega328P for larger Arduino sketches.
ATmega328P: The Classic Arduino Workhorse
The ATmega328P is the microcontroller used on many classic Arduino boards, including the Arduino UNO, Arduino Nano and Arduino Pro Mini. It has more memory, more mature Arduino support and more beginner-friendly documentation than most ATtiny options.
- 8-bit AVR microcontroller
- 32 KB flash memory
- 2 KB SRAM
- 1 KB EEPROM
- Used on many standard Arduino-compatible boards
- Good for general-purpose Arduino projects
The ATmega328P is often the best choice when project simplicity and Arduino compatibility matter more than the absolute smallest size or lowest cost.
Main Specification Comparison
| Feature | ATtiny85 | ATtiny88 | ATmega328P |
|---|---|---|---|
| CPU type | 8-bit AVR | 8-bit AVR | 8-bit AVR |
| Flash memory | 8 KB | 8 KB | 32 KB |
| SRAM | 512 bytes | 512 bytes | 2 KB |
| EEPROM | 512 bytes | 64 bytes | 1 KB |
| Typical Arduino board examples | Digispark-style boards, small ATtiny85 modules | ATtiny88 development boards and small compatible modules | Arduino UNO, Nano, Pro Mini |
| Pin count | Very limited | More than ATtiny85 | Enough for many general Arduino projects |
| Arduino beginner friendliness | Limited | Limited to medium | Excellent |
| Best known advantage | Very small and simple | More pins than ATtiny85 while still small | Best Arduino ecosystem support |
| Best known limitation | Very few pins and little memory | Still limited memory | Larger and more capable than needed for very tiny tasks |
Memory: The Biggest Practical Difference
Memory is one of the most important differences between these controllers. The ATtiny85 and ATtiny88 both have only 8 KB of flash memory and 512 bytes of SRAM. This is enough for very small programs, but it can become restrictive quickly when using libraries.
The ATmega328P has 32 KB flash memory and 2 KB SRAM, which is still small by modern standards, but much more comfortable for Arduino projects.
- ATtiny85: good for very small sketches
- ATtiny88: good for small sketches needing more pins
- ATmega328P: better for general Arduino sketches and libraries
Display libraries, communication libraries, large lookup tables and text strings can use memory quickly. If the project needs several libraries at once, the ATmega328P is usually the safer choice.
I/O Pins and Project Size
The number of usable pins often decides whether an ATtiny is practical.
The ATtiny85 is very compact, but its pin count is extremely limited. After power, reset and programming-related pins are considered, only a small number of pins remain for the actual project.
The ATtiny88 provides more I/O, making it useful for projects with more buttons, LEDs, sensor signals or simple outputs. The ATmega328P provides a familiar Arduino pin layout and enough pins for many everyday projects.
| Project Type | ATtiny85 | ATtiny88 | ATmega328P |
|---|---|---|---|
| One button and one LED | Very good | More than needed | More than needed |
| Small LED effect | Good if pin count is enough | Good | Very good |
| Several buttons and LEDs | Often too limited | Good | Very good |
| Multiple sensors and display | Usually too limited | Possible, but memory may become tight | Better choice |
| General Arduino learning | Not ideal | Not ideal | Best choice |
Arduino Compatibility
The ATmega328P has the strongest Arduino compatibility because it is the chip used on the classic Arduino UNO and Nano. Most tutorials, examples and libraries were tested on ATmega328P-based boards.
ATtiny boards can also be programmed through the Arduino IDE, but they often require additional board support packages, special bootloaders or programmer setup. Some Arduino libraries may not work without changes because they expect hardware features found on larger microcontrollers.
- ATmega328P is the easiest option for standard Arduino projects
- ATtiny85 is supported, but more limited
- ATtiny88 support depends on board package and bootloader
- Not every Arduino library works well on ATtiny controllers
Programming Differences
Many ATmega328P boards include a USB connector or are commonly available in USB-programmable formats such as the Nano. The ATtiny85 and ATtiny88 depend more heavily on the exact board design.
Some ATtiny85 boards, such as Digispark-style boards, use a USB bootloader. Other ATtiny boards require an ISP programmer or another Arduino used as a programmer.
| Programming Topic | ATtiny85 | ATtiny88 | ATmega328P |
|---|---|---|---|
| Typical programming method | USB bootloader on some boards, ISP on others | USB bootloader or ISP depending on board | USB on UNO/Nano, external adapter on Pro Mini |
| Beginner convenience | Depends strongly on board | Depends strongly on board | Usually very good |
| Arduino IDE setup | May require extra board package | May require extra board package | Built-in support for common boards |
| Risk of setup confusion | Higher for beginners | Higher for beginners | Low |
Communication Interfaces
Small ATtiny controllers do not provide the same comfortable communication options as larger Arduino boards. This is especially important when a project needs I2C, SPI, UART, displays, sensors or serial modules.
The ATmega328P is much easier for standard Arduino communication examples because most libraries assume its hardware layout or at least a similar level of peripheral support.
- ATtiny85 can do simple communication, but pins and hardware resources are limited
- ATtiny88 has more pins, but still limited memory
- ATmega328P is better for standard I2C, SPI and UART Arduino projects
- Software-based communication can consume memory and timing resources
Power Consumption
ATtiny controllers can be attractive for low-power projects, especially when the circuit is designed carefully and unnecessary board components are avoided.
However, the microcontroller chip is only one part of the power budget. Voltage regulators, power LEDs, USB interfaces and connected modules can draw more current than the controller itself.
- ATtiny85 is useful for tiny low-power circuits
- ATtiny88 can be useful when more pins are needed in a low-cost controller
- ATmega328P can also be used in low-power designs, especially on minimal boards
- Development boards are often not optimized for lowest possible sleep current
For real low-power work, the full board design matters more than the chip name alone.
When to Use ATtiny85
- Very small projects with only a few pins
- Simple LED effects
- Small timers or pulse generators
- Button-to-output logic
- Tiny embedded circuits where space matters
- Projects where the firmware is very small
The ATtiny85 is a good choice when the project is simple, the code is small and the pin count is enough.
When to Use ATtiny88
- Simple projects that need more pins than ATtiny85
- Low-cost control boards
- LED and button projects with moderate I/O count
- Small automation tasks where memory needs are limited
- Projects where ATmega328P would be larger than necessary
The ATtiny88 sits between the very small ATtiny85 and the more comfortable ATmega328P. It can be useful when pin count matters but the software is still simple.
When to Use ATmega328P
- Beginner Arduino projects
- General sensor and display projects
- Projects using standard Arduino libraries
- Prototypes that may grow later
- Projects where easier debugging and documentation matter
- Applications where 32 KB flash and 2 KB SRAM are enough
The ATmega328P is the safest choice for most classic Arduino work. It is not as tiny as an ATtiny85, but it is much easier to use for normal projects.
When Not to Use These Controllers
All three controllers are small 8-bit AVR devices. They are not the right choice for every modern project.
- Use ESP32 or ESP8266 if WiFi is required
- Use nRF52 or ESP32-C6 if modern wireless features are required
- Use RP2040, RP2350 or STM32 if much more memory or processing power is needed
- Use external GPIO expanders if the only problem is pin count
- Use external ADCs or DACs when better analog performance is required
For simple control tasks, AVR controllers are still excellent. For connected, high-speed or memory-heavy projects, a modern 32-bit board is usually more practical.
Which One Should You Choose?
| Project Need | Best Choice | Why |
|---|---|---|
| Smallest simple controller | ATtiny85 | Very small and enough for simple logic or LED projects |
| More pins than ATtiny85 | ATtiny88 | More I/O while still remaining a small AVR controller |
| Most Arduino-compatible option | ATmega328P | Best support in tutorials, libraries and standard Arduino boards |
| Using several libraries | ATmega328P | More flash and SRAM than ATtiny85 or ATtiny88 |
| Very small firmware, few pins | ATtiny85 | Low-cost, compact and simple |
| Simple project with many buttons or LEDs | ATtiny88 or ATmega328P | ATtiny88 can work if the code is small; ATmega328P gives more memory margin |
| Best beginner experience | ATmega328P | UNO and Nano boards are easier to set up and better documented |
Conclusion
The ATtiny85, ATtiny88 and ATmega328P are all useful classic AVR controllers, but they fit different project sizes.
- Choose the ATtiny85 for very small projects with only a few pins and very small firmware.
- Choose the ATtiny88 when you need more I/O than ATtiny85 but still only need simple software.
- Choose the ATmega328P for the best Arduino compatibility, more memory and the easiest beginner experience.
For most general Arduino projects, the ATmega328P is still the most practical choice. The ATtiny85 and ATtiny88 become interesting when the project is small enough that a full UNO or Nano-style controller would be unnecessary.