OnSpec xSil 258B – Hi-Speed USB Flash Media R/W Controller




OnSpec’s xSil 258B Flash media Controller is a USB to Media Multi-Slot controller. It takes advantage of the new media types with faster transfer rates and higher memory capacities. Industry standard flash memories and open standards like CF, SD and SD HC etc are supported. It is a complete System-On-Chip (SOC) solution for interfacing various flash media and CF Form-Factor ATA Hard Drives to Full Speed USB (USB 1.1) or Hi-Speed USB (USB 2.0) Bus.

OnSpec offers reference designs, firmware, drivers, and manufacturing test software to make product development easy. OnSpec’s patented technology provides optimum throughput and superior flash media compatibility.


  • Compatible with Microsoft Windows XP, Windows Me, Windows 2000, Windows 98, Windows 95b, Apple OS X and Linux Kernel V2.4 or later

  • Windows 2000, Windows 98/ 98SE/ 95b and Apple OS8.6 and OS9 Multi-LUN Mass Storage Class Drivers Available

  • Multiple Icons supported in Windows and Mac

  • Single and Multiple Connector Support

  • Single chip with integrated USB 2.0 PHY

  • Serial EEPROM support for sizes 256bits to 512KBits

  • Supports up 4 slots, and 4 icons at a time. (Application notes available.)

Block Diagram 



Functional Description

The xSil258B is designed to connect an IDE/ATAPI device or Flash media to USB. It contains the following:

  • 100-pin 16mm x 16mm QFP package

  • Single chip with integrated USB 2.0 PHY

  • Serial EEPROM port

  • Industry standard flash memories and open standards like CF, SD and SD HC etc are supported.Supports up to 25 types of media. (Application notes available.)

  • Supports On-board NAND as a storage device

  • Firmware enhancements can be stored on On-board NAND when populated

  • Serial port

  • Two General Purpose Timers

  • Watchdog Timer

  • 16 bit Processor

  • Internal RAM for supporting enhancements

  • ROM with BIOS and Application code

  • Programmable Read and Write widths

  • Optimum hardware controlled transfer for speed and scalability


The xSil258B is a 100-pin QFP package.

USB Engine

The xSil258B meets the Universal Serial Bus (USB) specification V2.0 and V1.1.

Serial EEPROM Port

The xSil258B provides a serial interface to access external EEPROM’s. The interface is implemented using General Purpose I/O signals and can support a variety of serial EEPROM formats.


The xSil258B processor can be designed to interface to an IDE or ATAPI device. It supports PIO mode of data transfer.

Serial port

Supports 7200 to 115.2K baud. It can be used as a debug port to communicate with V3 debugger and to load the monitor program.

General Purpose Timers

Two general-purpose timers, Timer0 and Timer1 are provided to allow firmware programmers to keep track of timeouts as well as to generate delays.

Watchdog Timer

A Watchdog Timer is provided to enable catastrophic events to interrupt the processor. The Watchdog Timer overflow causes an internal processor reset. The Processor can read the WT bit after exiting reset to determine if the WT bit is set. If it is set, a watchdog timeout occurred. The timeout is selectable to any of the following values: 2 second, 8 seconds, 16 seconds or 32 seconds.

xSil 258B Processor

The xSil 258B Processor has a built-in 16-bit processor along with a BIOS ROM. The processor operates with a specialized instruction set optimized for Mass Storage applications and USB transaction processing. The startup code for the 16-bit processor resides in a masked ROM.

RAM Interface

The xSil258B chip comes with Internal RAM that can be used to enhance the firmware resident in the ROM.

Masked ROM

The Masked ROM consists of the xSil258B processor start-up code and the functions listed below:

  • Power On Initialization

  • USB packet transaction management

  • USB Power Management (S0..S3 modes)

  • USB Enumeration Management

  • API support for USB transactions, EEPROM Interface, Memory Management etc.

  • Built-in Library functions for IDE/ ATAPI and Flash devices

The firmware is easily extended / expanded by using External Serial EEPROM. The BIOS provides several services to facilitate this expansion code. At boot-up time, the scan services of the BIOS search for the expansion signature in the Serial EEPROM as well as via the UART and USB. For more information, refer to Applications section of this manual.

The BIOS API functions are designed as Software Interrupts, making it easy for enhancements. Any Interrupt can be enhanced / modified by inserting the user defined function in the interrupt placeholder. When this interrupt is called by the BIOS, the user defined function is called first to enhance the behavior before passing it on to the standard BIOS function’s call or return without passing it on.

Programmable Read and Write cycles

The external cycles to flash using the D[15:0], and SM[7:0] bus are software configurable.

Ordering Information


Part Number



xSil 258B-G

USB to Multi Slot for all media with up to PIO 6 controller

100 LQFP Lead Free
(RoHS Compliant)


Technical and Design-in Information

Contact: sales@siliconapps.com

Design Support (Will be provided by OnSpec upon request)

  • Card Manufacturer Compatibility Testing (Software Release Notes)

  • Read/Write Performance Testing (Software Release Notes)

  • USB IF Certification Lab Report Summary

  • IBIS Models (Available on request)

  • Qualification Report

  • BIOS Boot Over USB Compatibility Testing Report

  • Flash Media Association Contact List

  • Memory Stick and xD Picture Card Certification and Lab Test Results

  • Card Reader Device Comparison

  • Embedded OS Compatibility Testing with XXXXXX MSC Driver

  • Reference board layout details click here to contact sales@siliconapps.com

Available from OnSpec under Software License Agreement (SLA):

  • Click Wrap SLA Agreement for Object Code on OnSpec Website

  • Manufacturing Utilities

  • Firmware up gradation through flash media

  • Software Release Notes (Important for Attribute Bit Settings and Descriptions)

  • Software Test Report (Matrix of OS and PC Chipset Testing)

  • Windows 98 and 2000 Multi-LUN Drivers

  • Vendor Specific Command Support Specifications with Source Code License

  • Email Notification of New Firmware Object Code Downloadable Over the OnSpec Secure Website


OnSpecLink® Family of Products
This product is covered by one or more of the following patents:
US Pat. 5841424, 6438638, 6832281, 6859361, 6859369
Taiwan Pat. I 222564
Other Foreign & US Patents Pending
Memory Stick Compliant Products Test Specification Extract Version1.1.00:
Certified, Reference: 20050401 (First controller in the world to get this certification)


Information in this document is provided in connection with OnSpec Electronic products. No license, express or implied, by estoppels or otherwise, to any intellectual property rights is granted by this document. Except as provided in OnSpec Electronic’s Terms and Conditions of Sale for such products, OnSpec Electronic assumes no liability whatsoever, and OnSpec Electronic disclaims any express or implied warranty, relating to sale and/or use of OnSpec Electronic products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement or any patent, copyright or other intellectual property right.

OnSpec Electronic products are not intended for use in medical, life saving, or life sustaining applications.


OnSpecLink Is a registered trademark of OnSpec Electronic, Inc.

All trademarks are the properties of their respective owners.

Download: Product Sheet PDF Size=144KB