SMC Networks LH79520 SoC ARM720T Manuel D’Utilisation

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. 

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. 

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 

•  MicroBlaze

™

 – 32-bit RISC processor targeted to Xilinx FPGA platforms. (Refer to the 

 

core reference). 

•  Nios

®

 II – 32-bit RISC processor targeted to Altera FPGA platforms. (Refer to the 

reference). 

•  CoreMP7 – 32-bit RISC processor targeted to Actel FPGA platforms. 
•  PPC405CR – AMCC

®

 PowerPC 32-bit RISC processor. (Refer to the 

 

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 

 core reference. 

CR0162 (v2.0) March 10, 2008