XMEGA, the latest addition to the AVR microcontroller family is here and it’s chock-full of advanced features. Although it is not widely available yet, it seems to have caused quite a stir in the AVR development community, and with sufficient cause. XMEGA is Atmel’s long overdue response to embedded developers looking for a platform a little more powerful than the existing 8-bit AVR series who have until now been forced to upgrade to a 32-bit architecture such as an ARM. This new microcontroller aims to fill the gap between an 8-bit platform and the 32-bit processor platform. Atmel has published an interesting Whitepaper(PDF) about the XMEGA. Here is a vry short version of the major improvements which make the XMEGA series stand apart:

• Superior Performance compared to the AVR: Higher performance in the XMEGA is achieved with the addition of two new features: higher clock speeds (with AVR already being able to operate ar 1MIPS/MHz, this improves it by a lot), a new DMA controller that saves cycles for the CPU by performing direct data transfer and a new event system which increases system responsiveness without increasing CPU overhead.
• Peripherals Galore: The XMEGA controller is filled to the brim with all kinds of peripherals: new 12-bit multi-channel ADCs, DACs, a crypto engine which implements the DES algorithm with one instruction, plenty of serial ports (upto 8 USARTs, 4 SPIs and 4 TWI interfaces) and better timers.

   

There’s even more to this. The development process for the XMEGA remains the same as the atmega series for the most part, so there’s no need to learn new tools or programming languages. AVR GCC is still supposed to be supported for XMEGA development. I’m still waiting to receive my XMEGA samples from the local Atmel rep. and hoping to check out these feaures on my own.

The topic of which 8-bit microcontroller is the best out there has probably been done to death, but I am going to contribute my two cents anyway. Undoubtedly, the two which have always come out on top of the battle are the AVR (Atmel) and PIC (Microchip). Having used both of these microcontrollers for the last few years now, I thought I will give my views on why I choose the AVR as the winner.

High Performance: In contrast to other microcontrollers, the feature that truly stands out is the fact that most of the instructions in the AVR instruction set can be executed in one clock cycle. Compare this to the 3-4 clock cycles required on average to execute an instruction on the PIC. This means that with a 16 MHz clock source, the atmega128 can achieve 16 MIPS which is truly high performance for this class of 8-bit microcontrollers.

Low Power: AVRs are not the lowest-power microcontrollers in the market, but there are certainly among the lowest. In addition to the low power editions of the standard microcontrollers (indicated by an ‘L’ after the part name), some of the popular AVRs including the ubiquitous atmega128 support what Atmel calls ‘picoPower’ technology (signified by a ‘P ‘at the end of the part number), the features of which include 1.8V device operation, optimized sleep functions and low power consumption in general (Atmel claims a 100 nA power drain in Power Down Sleep mode).

Strong Open-source support: Starting from the AVR GCC tools to the FreeRTOS operating system, most of the software development tools for the AVR are available for free as open-source tools. Because most of these tools integrate easily with AVRStudio -which is Atmel’s free IDE for software development-, they are easy to use for the novice while at the same time providing access to all the advanced options for the experienced user.

Besides these concrete reasons, the AVR is also fortified by its relatively lower cost - at an average price of about $15 a pop, the atmega128 is not the cheapest of the lot, but in terms of price-feature comparison it comes out on top- and the rich set of peripherals that comes with each AVR. I think these reasons and more will keep me using the AVR until Atmel decides to stop making them – which I don’t see happening any time soon.

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