CS22250 Datasheet, PDF (8/32 Pages) Cirrus Logic – WIRELESS 10BT CONTROLLER

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 Wireless 10BT Controller
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