CS22250 datasheet(8/32 Pages) CIRRUS

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CS22250 Wireless 10BT Controller

8 of 32

DS551PP2

Rev. 3.0

www.cirrus.com

3.5

Programmable Memory Controller

The CS22250 incorporates a general-purpose memory controller. The memory controller

supports both SDRAM/async SRAM memory interface and a FLASH memory interface.

In the RAM configuration, the system memory interface supports up to 4-Mbyte of 16-bit

SDRAM running at frequency up to 103 MHz single-state access cycles or 256KB of 16

bit async SRAM. The memory controller provides programming of SDRAM parameters

such as CAS latency, refresh rate etc; these registers are located in miscellaneous

configuration registers. The CS22250 memory controller supports power saving feature

of the SDRAM by toggling the Clock Enable (CKE) signal. When there are no pending

memory requests from any internal requester, the CS22250 will keep CKE low to cause

the SDRAM to stay in power down mode. Once a memory request is active, the CS22250

will assert CKE high to cause the SDRAM to come out of power down mode.

Typicallythis can reduce memory power consumption by up to 50%.

In ROM configuration, firmware for CS22250 is stored in non-volatile memory and is

accessed through the Boot ROM interface. The maximum addressable ROM space

supported is 1MB. ROM read/write and output enable are shared with RAM control pins.

3.6

Ethernet MAC Controller

The Ethernet MAC controller interface allows the Cirrus Logic CS22250 to provide

connectivity to an Ethernet local area network. The controller can be used to interface

with a cable or xDSL modem to share high speed internet multimedia and data traffic in a

wireless home network. The Ethernet MAC controller is fully compliant with the IEEE

802.3 standard. The controller supports both half-duplex CSMA/CD and full-duplex

operation at 10Mbps.

The Ethernet MAC incorporates two power safe modes. The first disable mode disables

the entire MAC core including clocks. The second is a partial sleep mode, which only

disables transmit logic. In this mode, the entire MAC is powered upon receiving an

Ethernet packet. The Ethernet MAC uses two independent DMA controllers to support full

duplex operations with the system memory. The DMA controller is programmed and

configured by the ARM.

3.7

USB Configuration Interface

The USB interface is a device interface that allows for bridge configuration from a USB-

enabled PC. Switching between normal and configuration modes is controlled by external

logic.

CS22250 датащи(PDF) 8 Page - Cirrus Logic