Electronic Design

Custom 8051 Fits FPGA

Surround an 8051 from a menu of standard peripherals.

Finding the right 8-bit MCU is easy when you can choose the configuration. Actel's Core8051 approach starts with a single-cycle processor core. Creating the rest of the system is a matter of adding devices, such as a 10/100-Mbit/s Ethernet interface or a high-speed serial SDLC link. Bus layout and header files are created automatically. It's even possible to place multiple 8051s in the same system.

Actel combines the various components using the Libero v5 IDE. It handles VHDL and Verilog designs. The Core8051 packages can be easily utilized and even combined with custom hardware, but this will require additional expertise. The key to the Core8051 approach is that all components are designed to work together, minimizing configuration and testing chores.

The Core8051 works with Actel's ProASIC and ProASIC Plus line of flash-based, reprogrammable FPGAs. These possess gate counts that range from 75,000 to 1 million. System designs can use both on-chip and off-chip memory. The latter requires inclusion of the off-chip memory interface.

Actel's approach will have a tough road to hoe if it goes head to head with fixed-function 8051s. It's simply cheaper to make many fixed-function devices, but the flip side is that it's very expensive to maintain a wide variety of different fixed-function devices. The difficulty for a developer is choosing a part that will be around for a solution's particular time requirements. MCU vendors continually deliver new devices and cut old ones from their line cards. This can leave developers in the lurch if they can't find or create a suitable replacement.

The Core8051 architecture processor costs can run as low as $0.35/MIPS. That's more expensive than something like Cygnal Integrated Products' 100-MIPS C8051F120 8051, which is $9.44 or $0.0944/MIPS, but it's less than alternative soft core designs. Likewise, many multiple-cycle 8051 designs have a higher per-MIP cost than even Actel's solution. The price/performance requirement isn't always at the top of a developer's list, but Actel's solution can be competitive when it is a key consideration.

The entire collection of devices is available for $25,000 per project. The Core8051 alone starts at $9995, with devices being available individually. A development kit is priced at $550 and includes a board built around an Actel APA-600 FG676. The development kit incorporates a Web-server application running on a Core8051 and Core10/100. Evaluation software and a TCP/IP stack are included. FlashPro Lite JTAG support is optional.


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