Alternatively, silicon manufacturers can adopt a Customer Specific Standard Product (CSSP) based on a programmable fabric platform. A CSSP is different from an FPGA in that a CSSP is a customized product, but uses an off-the-shelf silicon platform. As such, all the customization is done for the OEM -- once the specification is agreed upon, the CSSP provider implements the solution and then assists the OEM with integration and test to ensure success. In contrast, using an FPGA requires OEMs to employ a completely separate development system, invest in extensive design work, add steps in manufacturing for programming the silicon, and manage additional complexity during system startup.
A CSSP gives OEMs the agility to bring features to market quickly without the complexity or delays associated with other technologies. This flexibility enables OEMs to offer unique, application-specific functionality that differentiates their processor from its competition. In addition, the cost, board space, and power savings of using an application processor plus CSSP make it an efficient option.
Use Case: Sitara AM335x
To understand how a CSSP can impact market response to an application processor vendor, consider the Sitara AM335x from Texas Instruments. This general-purpose ARM-based processor offers the performance and ease-of-design required for a wide range of embedded applications. However, for applications like scanners, security cameras, and machine vision, it lacks a standard camera interface (CAM IF). Developers have the option of using a USB-based image sensor, but this is less than ideal given that the AM335x has limited USB ports that are required for other functions. Also, USB image sensors are more costly and consume substantially more power than CAM IF-based sensors.
By creating a CSSP that bridges the AM335x’s GPMC interface with an image sensor’s CAM IF, the processor gains an extended market scope. The CSSP supports 720-pixel resolution at 30 frames/s, and up to 5-Mpixel resolution at 6 frames/s, while consuming less power than an equivalent USB-based camera sensor. In addition, no additional software development is required to implement the CSSP into the design.
For applications such as portable data terminals, most Sitara and OMAP processors don’t have enough UARTs to support the various peripherals or modules (i.e., ID barcode, Bluetooth, GPS, RS-232, RF, IrDA, etc.) these devices require. Similarly, point-of-sale (POS) terminals need multiple Secure Access Module (SAM) controllers to connect to different smart card systems.
For these applications, QuickLogic has created reference designs to provide additional UART and SAM controllers to their application processors via SDIO. The programmable fabric inside the CSSP enables flexible configurations to match the CSSP interface to the processor as well as adjust the number of UARTs and SAMs supported.
Designing a CSSP
One of the key benefits of a CSSP to OEMs is that they don’t have to design the device themselves. Silicon vendors, too, don’t want to be burdened with committing design personnel to creating a companion chip. However, they also don’t want to be occupied with creating variants of a chip for secondary markets when they could be focused on next-generation processor designs.
The CSSP design process, because of its programmable fabric foundation, enables a short design cycle built upon established libraries called proven system blocks (PSBs). Designing a CSSP begins with the silicon manufacturer and OEM co-defining the architecture and functionality that the CSSP needs to provide. The specification is then built by a system engineering team using existing PSBs with support for a range of buses, interfaces, and capabilities, thereby enabling custom designs to be implemented quickly without extensive design effort. This approach accelerates implementation, integration, and testing so that a CSSP can be brought to market in just a few months with limited involvement from the silicon manufacturer.