Lattice ISPLSI2032A: Architecture, Features, and System Design Applications

The Lattice ISPLSI2032A stands as a significant device within the high-density in-system programmable logic (ISPLSI) family. As a cornerstone of many digital designs in the late 1990s and early 2000s, its efficient architectural balance of capacity, speed, and power continues to offer valuable insights and practical utility for specific embedded and control applications.

Architecture: A Hierarchical Approach

The architecture of the ISPLSI2032A is built upon a highly integrated, hierarchical structure. At its core are 32 Generic Logic Blocks (GLBs), each containing programmable combinational logic and storage elements. These GLBs are interconnected by a global routing pool (GRP), a central switch matrix that provides 100% routability between all GLBs and input/output pins.

Surrounding the device are four dedicated output routing pools (ORPs). These ORPs connect the GLB outputs to the versatile I/O cells, which can be configured for various logic standards and bidirectional operation. A key architectural feature is the dedicated clock network, featuring five clock input pins that can be distributed to all GLBs and I/O cells, ensuring high-performance and low-skew clock management.

Salient Features

The ISPLSI2032A is characterized by a set of features that made it a competitive CPLD solution:

High Logic Density: With an equivalent gate count of 1000 gates and 32 registers, it was well-suited for integrating multiple TTL devices and SSI/MSI logic into a single chip.

In-System Programmability (ISP): Utilizing the IEEE 1149.1 (JTAG) interface, the device could be programmed and reprogrammed after being soldered onto the printed circuit board. This drastically simplified prototyping, field upgrades, and design iterations.

5V In-System Programmable Technology: As a 5V core device, it offered robust noise immunity and direct compatibility with the prevailing TTL logic systems of its era.

High-Speed Performance: Pin-to-pin delays as low as 7.5 ns enabled the design of state machines and logic circuits operating at frequencies exceeding 100 MHz.

System Design Applications

The combination of its architecture and features made the ISPLSI2032A ideal for a wide range of digital logic applications, often serving as a "glue logic" device or a dedicated controller. Key application areas included:

Address Decoding and Bus Interface: Generating chip selects and control signals for microprocessors (e.g., 8051, 68k) and memory systems (RAM, ROM).

State Machine Design: Implementing complex finite state machines (FSMs) for control sequences in data communication, processing, and industrial systems.

Data Path Control and Routing: Managing data flow between different subsystems, such as between a CPU and peripheral interfaces.

System Integration: Consolidating numerous discrete logic ICs (e.g., 74-series logic) into a single, compact, and reliable CPLD, reducing board space and improving overall system reliability.

ICGOODFIND: The Lattice ISPLSI2032A exemplifies a pivotal generation of CPLD technology. Its robust, routable architecture and foundational ISP capability provided designers with a powerful tool for system integration and logic consolidation. While newer, lower-power families have since emerged, the principles embedded in the ISPLSI2032A remain relevant, and the device itself continues to be a viable solution for maintaining and upgrading legacy electronic systems.

Keywords:

In-System Programmability (ISP)

Generic Logic Block (GLB)

Programmable Logic Device (CPLD)

Glue Logic

JTAG Interface