This is a budget no-name Arduino UNO SMD clone with an CH340G USB interface rather than an ATmega16U2, and a ceramic resonator instead of the more precise and stable 16MHz crystal oscillator. My example had a very crookedly mounted USB-B socket, and when I tried to resolder it flat onto the board it shorted something, disabling the USB port - so had to undo my fix :-(, and put up with it pressing on the underside of any Arduino shield mounted above.

So a cheap Arduino Uno clone for applications not requiring precise timing or expectations of longevity :-).

• Microcontroller: ATmega328P
• Clock Speed: 16 MHz ceramic resonator
• 14 digital input/output pins (6 can be PWM outputs)
• 6 analog inputs
• Operating Voltage: 5V
• Input Voltage: 7-12V
• 3.3V Power Out: up to 50 mA
• 5V Power Out: up to
• I/O Pin Out: up to 20 mA
• Digital I/O Pins: 14 (6 support PWM output)
• Analog Input Pins: 6 (with 10-bit resolution)
• Flash Memory: 32 kB (2kB used by bootloader)
• SRAM: 2 kB
• EEPROM: 1 KB
• Serial I/O: 4 UARTs, one SPI and one I2C interface

^{1) 2)}

Seems to be the same as this schematic but an MIC5205-3.3YM5 (labelled KB33 on a SOT-23-5 SMD chip) has been substituted for the LP2985-33 LDO regulator.

³⁾

• Arduino UNO SMD docs
• Pinout details (official)
• Schematic

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