Looking for a low power Cortex-A platform for a multimedia design? Then the Cortex-A5 may be what you need. It is the basis for the Atmel's 536MHz ATSAMA5D33 embedded processor.
The ATSAMA5D33 is a single core Cortex-A5 platform that comes in a BGA324 package. It has 160 I/O pins, three USB ports with PHYs, six SPI ports, three I2C ports, five UARTS, a CAN port, four LIN ports, four PWMs, and a pair of SCC ports. The chip has a single Ethernet port. On the analog side is a 12-channel, 10-bit ADC that can take 440 Ksamples/s. The security accelerator supports Advanced Encryption Standard (AES), Triple Data Encryption Standard (3DES) and Secure Hash Algorithm (SHA).
There is a 128 Kbytes of on-chip SRAM. There is an off-chip NAND interface and a DRAM interface that supports DDR2/LPDDR and SDRAM/LPSDR. The impedance control on the DRAM controller eliminates the need for external serial resistors.
Unlike the low end Cortex-M3, the ATSAMA5D33 has floating point and memory management support that is compatible with the higher end Cortex-A9 and Cortex-A9. It also has a resistive touch interface that is not as responsive as capacative touch platforms but the displays are less expensive. Resistive touch also works with things other than a finger.
I used the ATSAMA5D33-EK (Fig. 1) to check out the platform. The processor is found on a module the fits under the LCD screen. It adds 625 Mbytes of DDR2 memory, 256 Mbytes of NAND Flash, 16 Mbtes of NOR flash, a 32 Mbit SPI Serial DataFlash, and 64 Kbytes of EEPROM. There is a microSD slot. The system has a MII/RMII Ethernet 10/100 port and adds ZigBee support via a 10-pin header for an Atmel RZ600 module. JTAG provides low level debug support.
Figure 1. The Atmel ATSAMA5D33-EK houses the Cortex-A5 on a plug-in module hidden under the LCD touch display.
The display side has a 5-in WVGA resistive TFT LCD module with four QTouch capacitive tough keys. There is also an HDMI connection. There is an image sensor interface that supports CMOS sensors.
The kit comes with cables but all the software and documentation is online. This includes Atmel's Studio 6 that is based on Microsoft's Visual Studio (see Visual Studio-based IDE Target AVR Microcontrollers). The toolset is designed to work with Atmel's platforms including the ATSAMA5D33-EK. It can be used for bare metal application work or applications that run on Linux or other operating systems that can run on the Cortex-A5.
The system comes with a good bit of demo software installed including U-Boot (Fig. 2) and Linux (Fig. 3).
Figure 2. The Atmel ATSAMA5D33-EK houses the Cortex-A5 on a plug-in module hidden under the LCD touch display.
The version of Linux on the demo is from Timesys. You can configure and download a free copy called LinuxLink Free Edition. Of course, what they want to sell is LinuxLink Pro Edition with unmetered support. That is definitely worth the money when design a production system but it is very nice to evaluate a fully functional system.
Figure 3. The system boots Linux running a simple graphical user interface that provides access to applications including a web browser.
LinuxLink Pro includes the TimeSys TimeStorm IDE based on the open-source Eclipse IDE. LinuxLink Free is just the operating system. Downloading and using the x86 Eclipse IDE is relatively painless but setting up a cross-platform development system is a bit more involved. Maintaining one is even more work. Most will prefer to work with a company like TimeSys when going into production.
The Cortex-A5 is not a speed demon but it does sip less power than its big brothers. The evaluation platform is ideal for evaluating system functionality. I liked the sample home control program which would be an ideal application for this type of system.
The system can be upgraded because the processor is on a module. This can be handy if the application requirements grow.