SI-C665x Board
A powerful Keystone I single and dual core Digital Signal Processor (DSP) card for the PCIe bus.


The SI-C665xDSP from Sheldon Instruments is a C programmable Digital Signal Processor (DSP) card designed for low power environments that require intensive computing in a cost sensitive solution.

Keystone I devices supported on the SI-C665xDSP card:
TMS320C6657 (2 DSP CorePacs)
TMS320C6655 (1 DSP CorePac)
TMS320C6654 (1 DSP CorePac)

The SI-C665xDSP is a Small Form Factor (SFF) family of Commercial Off the Shelf (COTS) cards featuring the powerful Keystone I TMS320C665x DSPs from Texas Instruments. The TI C665x DSPs are single and dual core DSP System on Chip (SoC), conveniently programmed using the C language. Each C665x CorePac is clocked from 850Mhz to 1.25GHz for a maximum of 80 GMAC and 40 GFLOP performance at a mere 4 watts of power consumption.

Each DSP CorePac features 32K Bytes L1P, 32K Bytes L1D, and 1M Bytes of L2 of internal memory. Each level of cache can be programmed in blocks as SRAM or cache. The C665x chip also features a multicore shared memory controller that arbitrates 1M Bytes of shared SRAM memory between all cores and an external 64-bit DDR3 memory interface at 1333MHz.

High Speed Serial Interfaces: GbE, PCIe, & SRIO
There are multiple high speed interfaces, with each capable of moving large amounts of data. The Gigabit Ethernet interface can take advantage of the on-chip Network Co-processor to offload most of the packet processing, thereby enabling full bandwidth utilization and freeing up the DSPs to perform the computations for which they were designed. A PCIe x2 Gen 2.0 interface provides connectivity to a system backplane or a Thunderbolt cable, and the flexible SRIO 2.1 x4 5Gbps interface can be connected to either an optional FPGA or other external peripherals.

Hardware Expansion with FPGA & FMC Interface
The optional Altera Cyclone V GX FPGA includes SI’s proprietary IP layer that transparently translates SRIO so the FPGA may be used as an extra processing resource, as well as an expansion bridge to either an FPGA Mezzanine Card (FMC), or a legacy style parallel expansion bus – ideal for those who prefer to leverage a wide array of 3rd party FMC modules, their own custom hardware or simply update legacy designs with minimal effort.

Upgrade options for the SI-C665xDSP include memory configurations, nonvolatile storage, and either commercial or expanded temperature ranges. A full line of software development tools are available from Sheldon Instruments and TI for Windows and Linux platforms.


  • Real Time Image Processing
  • Machine Vision
  • Unmanned Aerial Vehicle Control Systems
  • Industrial Control and Automation
  • Additive Manufacturing
  • Medical Imaging
  • Military and Aerospace
  • Test and Measurement
  • FMC interface leverages expansion hardware choices

Block Diagram

PCIe-104 Diagrams

The SI-C665xDSP is available with extensive development tools from Sheldon Instruments, TI and Intel.

Host Side Tools
For the host PC side, Sheldon Instruments provides Windows/Linux 32/64 bit drivers, along with comprehensive sample application projects, with easy to use API libraries and related source code. The sample projects will be supplied as a command line utility, with a companion Qt GUI version. Its functionality includes:

  • Load ELF/EABI files created from TI’s Code Composer Studio (CCS) to any one of the user specified cores, and also enable the core to execute its program.
  • Comprehensive communications with read and write functionality to demonstrate single register, a register array, and DMA accesses.
  • A messaging scheme will be implemented allowing for either the host PC or the DSP to alert the other for user defined asynchronous events.

DSP Side Tools
For the DSP side, TI offers Code Composer Studio Integrated Development Environment (CCS), and the Multicore Software Development Kit (MCSDK) that includes the Board Support Package (BSP), Chip Support Library (CSL), Network Development Kit (NDK), and Sys/Bios. Sheldon Instruments provides various TI CCS projects for the DSP, both compiled versions for quick loading with the host side sample program, along with complete projects and related source code. These DSP projects include:

  • A bare low-level runtime initializer to demonstrate how to setup DSP entry points.
  • A project to demonstrate TI SYS/Bios usage and initialization.
  • Various projects to demonstrate initialization and usage of the C667x system components. In particular, configuration of the DDR3 module, Ethernet (with a stack or using the packet accelerator), EDMA3 transfers, and the Onchip Interrupt Controller.

There is important information for developers available from Texas Instrument’s website.

FPGA and FMC Expansion Side Tools
For the optional FPGA and FMC inbterface, Intel offers the Quartus Prime Development Software that includes the free Lite Edition for the Cyclone V GX family. Sheldon Instruments provides various utilities FPGA projects and related source code which include:

  • A DSP side utility to conveniently and quickly load the FPGA’s RBF configuration file, removing necessity for an onboard configuration PROM.
  • SI’s proprietary SRIO IP layer that transparently translates the high speed link between DSP-FPGA.
  • Various projects to demonstrate the FPGA to FMC interface to easy hardware expansion.

There is important information for developers available from Intel’s website.

Keystone I C665x Processor Resources
For more detailed documentation, check out the SI-C66xx Keystone I Wiki Homepage

Processor for SI-C665xDSP

TI Keystone I TMS320C665x Family
Number of Cores TMS320C6657 2
TMS320C6655 1
TMS320C6654 1
DSP Subsection (each C665x CorePac) Clocking 850Mhz-1.25GHz
GMACS/GFLOPS 44.8/22.4
L1 Program Cache/SRAM 32KB
L1 Data Cache/SRAM 32KB
L2 Cache/SRAM 512KB
Shared L2 Cache/SRAM 4MB


External DSP Memory

DDR3 Memory
Port A Size 512MB (64M x 64) to 2GB (256M x 64)
Speed 667Mhz Clock Rate (1333Mhz Effective Data Rate)


Storage / Nonvolatile Memory
SPI up to 64Mbit (8Mbx8) Flash
microSD flash card
I2C up to 2KB EEPROM (inside Tiva uC)


Optional Altera Cyclone 5 GX FPGA

Resource C3 C4 C5 C7 C9
Logic Elements (LE) (K) 31.5 50 77 149.5 301
ALM 11900 18868 29080 56480 113560
Register 47600 75472 116320 225920 454240
M10K 1190 2500 4460 6860 12200
MLAB 159 295 424 836 1717
Variable-preicision DSP Block 51 70 150 156 342
18 x 18 Multiplier 102 140 300 312 684
PLL 4 6 6 7 8
SRIO Lanes @ 3.125Gbps 2 4
BGA Package Density 484 or 672 pins


Other Altera, Xilinx or Lattice devices also available on special request.

Optional External FPGA Memory (PCIe Only)

DDR3 Memory
Size 256MB (64M x 32) to 1GB (256M x 32)
Speed 400Mhz Clock Rate (800Mhz Effective Data Rate)


High Performance Serial Interfaces

Interface Lanes Speed
PCI Express Gen2 Desktop PCIe: 2 5 Gbps
PCIe-104: 1 or 2
Thunderbolt: 2
SRIO rev2.1 4 5 Gbps
Gigabit Ethernet 1 10/100/1000 Mbps



Port Connectors
DSP Ports (all form factors) PCIe Gen 2 Root Complex or Endpoint
Ethernet RJ45 with integrated magnetics and LED indicators
microSD standard socket for microSD/SPI flash
JTAG One keyed 14 pin (2×7) header; compatible with all third party emulators and debuggers
DSP Ports (Desktop PCIe only) Optional RS-232 UART One 10 pin (2×5) header
Tiva uC USB microAB for card configuration


Optional Peripheral Expansion
SRIO x4 lane Expansion Desktop PCIe: SRIO port directly connects to optional onboard FPGA which serves as a bridge to an FMC expansion connector
PCIe-104: SRIO port brought out to third segment of QMS connector or Searay connector to stack a separate FPGA carrier with an FMC expansion connector
FMC/Parallel Expansion (available with FPGA option only) One HPC FMC connector


Mechanical Properties

Physical Dimensions/Electrical Requirements/Temperature
Form Factor Dimensions Desktop PCIe (3/4 size): 9″/23cm(L) x 4.9″/12.5cm(W)
PCIe-104: 4.55″/11.6cm(L) x 3.775″/9.59cm(W)
Weight 0.31lbs/140 grams
Supply Voltages 3.3V @ 0.5A and +12V @ 0.5A
Power 6 Watts typical; up to 12W with optional FPGA
Temperature Commercial grade 0-85C. Consult factory for availability of industrial and military temperature grades


PCIe Form Factor Cards

Product Description Price (US dollars)
SI-C6657DSP-PCIe TMS320C6657 – 2 DSP CorePacs Call
SI-C6655DSP-PCIe TMS320C6655 – 1 DSP CorePac Call
SI-C6654DSP-PCIe TMS320C6654 – 1 DSP CorePac Call


PCIe-104 Form Factor Cards

Product Description Price (US dollars)
SI-C6657DSP-PCIe104 TMS320C6657 – 2 DSP CorePacs Call
SI-C6655DSP-PCIe104 TMS320C6655 – 1 DSP CorePac Call
SI-C6654DSP-PCIe104 TMS320C6654 – 1 DSP CorePac Call


FPGA Options

Product Description Price (US dollars)
-C3 x2 SRIO @ 3.125Gbps – 31k Gates Call
-C4 x4 SRIO @ 3.125Gbps – 50k Gates Call
-C5 x4 SRIO @ 3.125Gbps – 77k Gates Call
-C7 x4 SRIO @ 3.125Gbps – 149k Gates Call
-C9 x4 SRIO @ 3.125Gbps – 301k Gates Call