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
[table class=”siTB”]
TI Keystone I TMS320C665x Family[attr colspan=”3″]
Number of Cores[attr rowspan=”3″], TMS320C6657, 2
TMS320C6655, 1
TMS320C6654, 1
DSP Subsection (each C665x CorePac)[attr rowspan=”5″], 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[attr rowspan=”1″], L2 Cache/SRAM, 4MB


External DSP Memory
[table class=”siTB”]
DDR3 Memory[attr colspan=”3″]
Port A[attr rowspan=”2″], Size, 512MB (64M x 64) to 2GB (256M x 64)
Speed, 667Mhz Clock Rate (1333Mhz Effective Data Rate)


[table class=”siTB”]
Storage / Nonvolatile Memory[attr colspan=”2″]
SPI[attr rowspan=”2″], up to 64Mbit (8Mbx8) Flash
microSD flash card
I2C, up to 2KB EEPROM (inside Tiva uC)


Optional Altera Cyclone 5 GX FPGA
[table class=”siTB”]
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[attr colspan=”4″]
BGA Package Density, 484 or 672 pins[attr colspan=”5″]


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

Optional External FPGA Memory (PCIe Only)
[table class=”siTB”]
DDR3 Memory[attr colspan=”2″]
Size, 256MB (64M x 32) to 1GB (256M x 32)
Speed, 400Mhz Clock Rate (800Mhz Effective Data Rate)


High Performance Serial Interfaces

[table class=”siTB”]
Interface, Lanes, Speed
PCI Express Gen2[attr rowspan=”3″], Desktop PCIe: 2, 5 Gbps[attr rowspan=”3″]
PCIe-104: 1 or 2
Thunderbolt: 2
SRIO rev2.1, 4, 5 Gbps
Gigabit Ethernet, 1, 10/100/1000 Mbps



[table class=”siTB”]
Port Connectors[attr colspan=”3″]
DSP Ports (all form factors)[attr rowspan=”4″], 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


[table class=”siTB”]
Optional Peripheral Expansion[attr colspan=”2″]
SRIO x4 lane Expansion[attr rowspan=”2″], 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
[table class=”siTB”]
Physical Dimensions/Electrical Requirements/Temperature[attr colspan=”2″]
Form Factor Dimensions[attr rowspan=”2″], 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
[table class=”siTB”]
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
[table class=”siTB”]
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
[table class=”siTB”]
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