Let's look at a simple comparison of the preceding boards for quicker reference:
| Content | Arduino Mega | STM32F103C8/T6 | ESP8266 | OpenCR | Arbotix Pro |
| Microcontroller | ATMega 2560 | ARM Cortex-M3 | Tensilica L106 32-bit processor | STM32F746ZGT6 / 32-bit ARM Cortex®-M7 with FPU |
STM32F103RE Cortex M3 32bit ARM |
| Operating Voltage | 5V | 2V ~ 3.6V | 2.5V ~ 3.6V | 5V | 2V ~ 3.6V |
| Digital I/Os | 54 | 37 | 16 | 8 | 16 ADC/GPIOs |
| PWM I/Os | 15 | 12 | - | 6 | |
| Analog I/Os | 16 | 10 | 1 | 6 | |
| Flash memory | 256 KB | 64 KB | External Flash (512 KB to 4 MB typically included) | 2 MB | 512 KB |
| Clock speed | 16 MHz | 72 MHz | 24 MHz to 52 MHz | 216 MHz | 72 MHz |
Comparison of preceding MCU boards
Now that we know the basics of microcontroller boards, let's look at single-board computers.