Functional Description

The 90C46D is designed to connect a wide range of memory cards to a CF^TM, PCMCIA, ATAPI or ATA slot. It contains the following:

• 100-pin LQFP package

• Serial EEPROM port

• Host side support

• CF^TM

• ATA

• ATAPI

• PCMCIA

• Card side support:

• Memory Stick^TM / Memory Stick Pro^TM / Memory Stick Duo^TM

• Secure Digital^TM

• SD^TM / Mini SD^{TM /} Micro SD^TM

• MMC^TM / RS MMC^TM / MMC Micro^TM

• CompactFlash^TM

• Microdrive^TM

• SmartMedia^TM

• xD^TM

• PCMCIA

• NAND / NAND MLC

•  Serial port

•  Two General Purpose Timers

• Watchdog Timer

• 16 bit Processor

• Supports 4-bit mode transfers for Memory Stick PRO and Memory Stick HS media

• Supports 1-bit ECC for NAND, NAND MLC and NAND Big block flash media

• Programmable read and write widths

• OnSpec?s patent pending EDMA technology for optimum data transfer

• Supports PIO 4 mode

• ATA-4 spec compliant*

* - As applicable to Flash media

Packaging

OnSpec 90C46D is a 100-pin LQFP package.

CF/PCMCIA/ATA Interfaces

The 90C46D provides a slave interface to a CF, PCMICA, or ATA slot.  Memory Mode, I/O Mode, and True IDE modes are supported. Please refer to Configuration Option Registers for more details.

Serial EEPROM Port

The 90C46D 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.

Support for CF, MMC / SD, Memory Stick and SmartMedia Cards

The MultiMediaCard (MMC), Secure Digital Card (SD Card) and Memory Stick are serial access devices. They also require in-bound / out-bound data to be appended with CRC information. The 90C46D processor provides support in hardware to generate the CRC and to convert Serial to Parallel and Parallel to Serial bit streams. A programmable clock speed is provided to set the clock speed based on the media?s capabilities. The 90C46D also provides ECC generation and checking for SmartMedia. CF cards may be connected directly as an ATA device.

Serial port

Supports 7200 to 115.2K bauds. It is useful as a debug port and can also be used to access the EEPROM for Reads / Writes from the serial port.

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 watch dog timeout occurred.

90C46D Processor

The 90C46D 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 CF transaction processing. The start up code for the 16-bit processor resides in a masked ROM.

RAM

The 90C46D chip comes with an Internal RAM.

Masked ROM

The Masked ROM consists of start-up code for the 90C46D processor and many other functions as listed below:

• Power On Initialization

• Scan for External ROM

• CF

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

• Built-in Library functions for Flash devices

The firmware can be easily extended / expanded by using External Serial EEPROM. 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 Serial EEPROM as well as via the UART. For more information on this, 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 user defined function in the interrupt placeholder. When this interrupt is called by the BIOS, the user defined function gets called first so it can enhance the behavior before passing it on to the standard BIOS function call or return without passing it on.

Programmable RD and WR cycles

The external cycles to SmartMedia are software configurable