Battery powered devices can take advantage of being connected to a USB port to recharge. However, modern batteries require sophisticated algorithms to accelerate and optimize charging, while USB brings further constraints on the battery charging since it is limited both in the voltage and the maximum current it can provide. The new AVR devices allow optimized battery charging combined with USB functions. The analog to digital converter can be used to sense motion or pressure in the end application and the high-speed PWM is ideal for low cost motor control.

Gaming peripherals, such as sophisticated joysticks also require a number of analog to digital conversion channels and several PWM channels to drive force-feedback motors. The new devices have a rich feature set that address those needs and optimize the global system cost. This includes a 10-bit ADC with 12 channels; a built-in temperature sensor allowing compensating thermal effects on analog performance; a programmable gain x1, x10, x40 and x200 giving more flexibility to measure differential voltages for current monitoring. A high-speed timer with three PWM channels with complementary outputs and programmable dead-times allows 8-bit resolution PWM with an industry-best frequency of 500 kHz, up to 11-bit resolution PWM with a frequency over 60 kHz.

A hardware flow control on the USART eases the connection to other devices when bridging with USB at high baud rates. Digital inputs with TTL thresholds ease interface with 3V devices in mixed 5/3V applications. A On-Chip 3.3V regulator can deliver up to 50 mA and supply external devices in USB powered applications. Jitter and accuracy of the On-Chip 8 MHz calibrated RC oscillator can support serial communication without crystal. All devices include a hardware multiplier, one USART, one SPI, one TWI, two 8-bit and two 16-bit timers with PWM and 26 programmable I/Os.

ATmega16U4 features 16 Kbytes of In-System Programmable (ISP) Flash, 1 Kbytes of RAM and 512 bytes of EEPROM. ATmega32U4 features 32 Kbytes of In-System Programmable (ISP) Flash, 2.5 Kbytes of RAM and 1 Kbytes of EEPROM. They are available in 44-pin packages.

"The new microcontrollers complement the existing family of AVR USB microcontrollers serving a variety of embedded host or peripheral USB applications," said Jean-Christophe Lawson, Atmel's AVR Product Marketing Manager. "Smaller foot print and enhanced analog performance was requested for several USB-based applications and we are pleased to introduce a new combination of features that will optimize the performance and cost of the customer's applications."

An extensive software library is offered to support the most-relevant USB classes for the embedded market: Mass Storage Device (MSD), Human Interface Device (HID), Device Firmware Upgrade (DFU), Communication Device Class (CDC), Audio Class, etc. Examples of composite devices actually combine several classes in one device, for instance Audio and HID can be combined to make a headset with remote control, toys, etc.

The parts are supported by the latest release of AVR Studio® which is available from the Atmel website. Both JTAGICE MkII at $299 and AVR Dragon at $49 allow in-system programming and emulation through On-Chip Debug resources (OCD). The STK®600-TQFP44 includes a dedicated adapter board so these specific devices can connect on the generic STK600 Starter Kit. By June 2008, this will be complemented by the EVK527 a standalone evaluation kit allowing the evaluation of HID, mass storage, audio and battery charging applications.

Availability and Pricing

ATmega32U4 engineering samples are available now and both devices will be shipping in volume in Q2 2008. ATmega32U4 is offered in TQFP44 and QFN/MLF44 packages at $2.65 in quantities of 10k units and ATmega16U4 is offered in a QFN44 package at $2.40 in quantities of 10k units.