Atmel ATmega32U4 44-pin TQFP

This is the Atmel ATmega32U4 chip used in Arduino Leonardo boards

Note: This chip DOES NOT have the Arduino Bootloader installed.

The ATmega32U4 is a low-power CMOS 8-bit microcontroller based on the AVR enhanced RISC architecture. By executing powerful instructions in a single clock cycle, the ATmega32U4 achieves throughputs approaching 1 MIPS per MHz allowing the system designer to optimize power consumption versus processing speed.

The ATmega32U4 provides the following features:

32K bytes of In-System Programmable Flash with Read-While-Write capabilities
1K bytes EEPROM
2.5K bytes SRAM
26 general purpose I/O lines (CMOS outputs and LVTTL inputs)
32 general purpose working registers
four flexible Timer/Counters with compare modes and PWM
one more high-speed Timer/Counter with compare modes and PLL adjustable source
one USART (including CTS/RTS flow control signals)
a byte oriented 2-wire Serial Interface
a 12-channel 10-bit ADC with optional differential input stage with programmable gain
an on-chip calibrated temperature sensor
a programmable Watchdog Timer with Internal Oscillator
an SPI serial port
IEEE std. 1149.1 comp liant JTAG test interface, also used for accessing the On-chip Debug system and programming and six software selectable power saving modes.
The Idle mode stops the CPU while allowing the SRAM, Timer/Counters, SPI port, and interrupt system to continue functioning.
The Power-down mode saves the register contents but freezes the Oscillator, disabling all other chip functions until the next interrupt or Hardware Reset.
The ADC Noise Reduction mode stops the CPU and all I/O modules except ADC, to minimize switching noise during ADC conversions.
In Standby mode, the Crystal/Resonator Oscillator is running while the rest of the device is sleeping. This allows very fast start-up combined with low power consumption.