ARM720T_LH79520 – Sharp LH79520 SoC with ARM720T 32-bit RISC Processor
Wishbone OpenBUS Processor Wrappers To normalize access to hardware and peripherals, each of the 32-bit processors supported in Altium Designer has a Wishbone
OpenBUS-based FPGA core that 'wraps' around the processor. This enables peripherals defined in the FPGA to be used
transparently with any type of processor. An FPGA OpenBUS wrapper around discrete, hard-wired peripherals also allows them
to be moved seamlessly between processors.
The OpenBUS wrappers can be implemented in any FPGA and allow the designer to implement FPGA-based portable cores,
taking advantage of the device driver system in Altium Designer for both FPGA-based soft-core peripherals as well as
connections to off-chip discrete peripherals and memory devices.
Processor Abstraction System Use of OpenBUS wrappers creates a plug-in processor abstraction system that normalizes the interface to interrupt systems
and other hardware specific elements. The system provides an identical interface to the processor's interrupt system, whether
soft or hard-vectored. This allows different processors to be used transparently with identical source code bases.
Design Migration With each 32-bit processor encased in a Wishbone OpenBUS wrapper, an embedded software design can be seamlessly
moved between soft-core processors, hybrid hard-core processors and discrete processors.
The Wishbone OpenBUS wrapper around the ARM720T_LH79520 processor makes it architecturally similar to the other 32-bit
processors included with Altium Designer, both in terms of its memory map and its pinout. This allows for easy migration from
the ARM720T_LH79520 to any of the following devices:
• TSK3000A – 32-bit RISC processor, device and vendor-independent. (Refer to the TSK3000A 32-bit RISC Processor core
reference).
• PPC405A – 'hard' PowerPC® 32-bit RISC processor immersed on the Xilinx Virtex-II Pro. (Refer to the PPC405A 32-bit
RISC Processor core reference).
• MicroBlaze™ – 32-bit RISC processor targeted to Xilinx FPGA platforms. (Refer to the MicroBlaze 32-bit RISC Processor
core reference).
• Nios® II – 32-bit RISC processor targeted to Altera FPGA platforms. (Refer to the Nios II 32-bit RISC Processor core
reference).
• CoreMP7 – 32-bit RISC processor targeted to Actel FPGA platforms.
• PPC405CR – AMCC® PowerPC 32-bit RISC processor. (Refer to the PPC405CR - AMCC PowerPC 32-bit RISC Processor
core reference).
Altium Designer also features Wishbone-compliant versions of its TSK52x 8-bit processor. These Wishbone variants, along with
true C-code compatibility between these and the ARM720T_LH79520, allow designs to be easily moved between the 8- and 32-
bit worlds.
For further information on the TSK52x, refer to the TSK52x MCU core reference.
4 CR0162 (v2.0) March 10, 2008