For years, Atmel has had the AVR microcontroller, known for its low power consumption and performance at 8b and 32b, but, somewhat less well known, the company has also had a very competitive RF transceiver. Today, Atmel announced a new family of AVR microcontrollers that combine these two functions in a single chip targeted at wireless applications such as ZigBee®, RF4CE, and 6LoWPAN. Specifically, the new ATmega128RFA1 is IEEE 802.15.4 compliant and combines Atmel’s picoPower® AVR MCU and a 2.4 GHz RF transceiver.

Here are the key specs as the chip was released:

To flesh out the story some more, I spent some time speaking with Magnus Pedersen, Atmel's product marketing manager for wireless MCUs. One of the key care abouts for designers will likely be the RF performance (the radio, by the way, is done in a 15um CMOS process). A +3.5dBm transmit power combined with Rx sensitivity of -100dBm results in a link budget of 103.5dB. This is a good point of comparison for you in an apples-to-apples evaluation of ZigBee radios.

Also noteworthy is the deep-sleep power consumption (when the controller and peripherals are asleep) is less than 250nA. This is all well and good, but how long does it take to wake up the MCU? According to Magnus Pedersen, the MCU wakes up in less than 70us and the device is ready to receive in 420us. This seems impressive to me. Any feedback?

When the MCU is active, the device consumes 0.26mA/MHz, another handy spec to use in a side-by-side comparison that depends on how you clock the device. To do the math, this means that at 16MHz, power consumption would be 4.1mA. When the radio is active the device draws <12.5mA in receive and <14.5mA in Tx. These are slightly better numbers than what was achieved with the standalone transceiver. 

When designing this device, Atmel also decided to include AES encryption in the hardware since some ZigBee applications mandate encryption. "And doing encryption in hardware is 10 to 100 times faster than in software," added Pedersen, "which saves time and power consumption."

The device also includes an antenna diversity function to address multipath fading. This is achieved completely in hardware, so no software required to make that work. The device will automatically select the antenna with stronger signal. It is also possible to add external PAs and LNAs to increase output power. (If you do choose to add a PA and LNA, the switching is still done from the chip.)

Another notable feature of this chip is its alternative data rates. Atmel designed it to be compliant to 802.15.4, but they also added higher data rates, up to 2Mbits/s, for non-ZigBee-compliant solutions. This enables the chip to support applications such as audio transfer, toys, and low resolution video.

In terms of creative design, the chip features hardware accelerators in order to reduce the software work and active time of the microcontroller. These allow the MCU to be asleep while the radio part is autonomously able to do a frame transmission and ACK reception.

The Atmega128RFA1 is available now with a suggested price of $4.78 for 10K quantities. Evaluation kits are also available, beginning at $79, containing two device cards and two 2.4GHz antennas.

For more information on Atmel's Atmega128RFA1product, click here. If you have any feedback, thoughts, questions, or musings on this product, please share your review below.