Flash FPGA Reprogramming With On-Chip Control and Bitstream Security

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Solution Overview

Problem

Flash-based FPGA devices require external reprogramming methods that are logistically difficult, expensive, and compromise security due to exposure of the bit stream, as existing methods necessitate external control, storage, and system intelligence for refreshing and updating the device configuration.

Innovation Solution

A flash-based programmable integrated circuit with on-chip intelligence that allows self-programming from an external data source, eliminating the need for external control, storage, and bit stream exposure, using a microcontroller or state machine to program and refresh the flash memory array directly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If external reprogramming methods are used for flash-based FPGA devices, then the device can be reprogrammed in the field, but the process becomes logistically difficult and expensive requiring external control and storage

Engineering Contradiction:

Improvein-field reprogramming capabilityVSAvoidexternal control and storage requirements

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements self-service by integrating a controller and memory cell array within the FPGA device that enables the device to reprogram itself autonomously. The controller manages the erasure and programming of configuration data in the memory cells without requiring external control logic, eliminating the need for external systems to store and manage bitstream data.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent merges the controller, memory cell array, and programming logic into a single integrated device structure. The controller is directly coupled to the memory cells, allowing the device to combine configuration storage and reprogramming functionality within its own architecture rather than relying on separate external systems.

Inventive Principle:

Principle #5Merging (Combining)

2Adaptability or versatility

If external systems store and transmit bit stream data for reprogramming, then the device can be updated, but security is compromised due to exposure of the bit stream

Engineering Contradiction:

Improveconfiguration update capabilityVSAvoiddesign security

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The device uses its internal controller to generate and manage configuration data autonomously. The controller reads configuration data from a source, processes it, and programs it directly into the device's memory cells without the bit stream leaving the device, thereby maintaining security through self-contained operation.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent extracts the bit stream generation and management functionality from external systems and places it entirely within the FPGA device. By taking out the external storage and transmission components and replacing them with internal memory and controller logic, the bit stream never exits the device boundary.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS7616508B1Flash-based FPGA with secure reprogramming

Publication Date: 2009.11.10 MICROSEMI SOC CORP

AI summary

A flash-based programmable integrated circuit includes programmable circuitry, a flash memory array coupled to the programmable circuitry for configuring it, flash programming circuitry for programming the flash memory array, and an on-chip intelligence, such as a microcontroller or state machine, coupled to the programming circuitry to program the flash memory from off-chip data supplied via an I/O pad, or to refresh the data stored in the flash memory to prevent it from degrading.