A Design Approach Based on the Intel Atom Processor
At the hardware level a high level block diagram for a modular PLC based on the Intel Atom processor is shown in Figure 4. By incorporating one of the industrial temperatures versions available in the Intel Atom processor family, which has the thermal footprint that enables fanless systems to be developed, the design is well-suited to the harsh environment found in many industrial settings.
The combination of the Intel Atom processor paired with the Intel System Controller Hub provides the majority of the interfacing required for the industrial control application. The Intel System Controller Hub measures 22 mm x 22 mm and provides integrated graphics, a digital-audio interface, a main-memory interface, and numerous peripheral I/O interfaces. It supports single-channel DDR2 memory. Front side bus (FSB) speed is 400 MHz or 533 MHz. Maximum memory is 2 GB. There are eight USB 2.0 host ports and one USB 2.0 client port. The parallel ATA interface supports two disk drives. System designers will add DRAM and physical-layer (PHY) chips for the features they wish to support. Additionally there are three fabrics: one for memory traffic, a second for I/O traffic, and a third message-based network that handles almost everything else. To manage these fabrics, the north bridge integrates an 8051 eight-bit microcontroller. The integrated 2D/3D graphics engine can drive a 1,366-pixel x 768-pixel display in 24-bit color. The integrated video engine can decode 1080p HDTV streams at 30 frames per second, using only 150 mW in the process. It supports MPEG1, MPEG2, MPEG4, and H.264 video and is compatible with Microsoft DirectX 9 and DirectX 10 graphics.
To enable all the fieldbus and real-time Ethernet protocols support is typically realized either with the OEM's own ASIC, or by using an FPGA. The FPGA in this case acts as an intelligent peripheral extender to this platform to add the industrial I/O not contained in the base Intel System Controller Hub.
Functionally the FPGA will interface to the Intel System Controller Hub through a single lane PCI Express interface. The FPGA is usually architected in such a way that it can be easily extended (or modified) for additional peripherals.
The interface allows exchanging the data between CPU and FPGA with very short latency times, typically in the range of microseconds.
Software running on Intel Atom processors will implement the protocol processing for fieldbus and real-time Ethernet. A number of independent software vendors deliver software stacks all delivering support for the IA-32 instruction set.
This design approach maximizes how open modular systems can be built for industrial automation. By incorporating the CPU and chipset on to a module and the industrial fieldbus and real-time Ethernet I/O on an FPGA, this solution easily scales to incorporate new CPU modules and to incorporate variances and new standards associated with industrial I/O.
The advantages with this design include:
- Maximum flexibility to incorporate support for industrial I/O.
- Low power that enables high performance fanless designs.
- PCI Express for high performance I/O.
- Extreme low power that enables rugged solutions for harsh environments.
- Integrated graphics for embedded HMI.
- Intel Hyper-Threading Technology (Intel HT Technology) that enhances real-time performance.
- Very slim housing and possible small form factor.
- Power over Ethernet (including TFT-Display).
- Miscellaneous functions integrated into one peripheral FPGA (LPC, FWHI/F, keyboard touch controller, bus-interface like Ethernet, CAN, and so on).
- Easy adoption of various industrial buses I/F with standard interconnect modules.
Today traditional industrial control using proprietary architectures has been superseded by new PC-based control systems that are generically referred to as open control. Open control gives the engineer the freedom of choice of the hardware platform, the operating system, and the software architecture. Instead of fitting an application into a predefined architecture, the designer has the choice of hardware and software components, to exactly meet the requirements of the design while drastically reducing costs and time to market. Open control provides standardization. Open control systems can be programmed using any of the IEC 61131 standard languages. Commonly available processors such as the Intel Architecture family can be used. Commonly available solutions can be provided by manufacturers or a customer specific design can be created by selecting the appropriate component.
The Intel Atom processor is designed in the Intel architecture tradition of providing general purpose computing platforms. The power of the customer application is unlocked by the versatility and power of the software applications that may be designed on the platform. The Intel Atom processor is fully compliant with the IA-32 architecture, enabling designers to use the vast software ecosystem to ensure fast time to market for new designs.
The advantage to end users includes the ability to leverage a common well known architecture from high end industrial PCs right down to low level intelligent field devices and PLCs. Developing on a common platform architecture also simplifies the convergence challenge between corporate IT and automation systems. The ability to develop real-time systems using open standards on scaleable platforms can bring significant benefits to developers in terms of engineering reuse as well as bringing products to market quickly and efficiently.
In conclusion, designing with the Intel Atom processor, brings all of the benefits traditionally associated with Intel architecture designs to the low power or "real" embedded market.
This article and more on similar subjects may be found in the Intel Technology Journal, March 2009 Edition, "Advances in Embedded Systems Technology". More information can be found at http://intel.com/technology/itj.