CS22210 Datasheet, PDF (7/31 Pages) Cirrus Logic – WIRELESS PCI/USB CONTROLLER

3.4 Programmable Memory Controller
The CS22210 incorporates a general purpose memory controller that supports a
SDRAM/async SRAM memory and FLASH memory interface.
In the RAM configuration, the system memory interface supports up to 16-Mbyte of 16-bit
SDRAM running at a 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. When there are no pending memory requests from any internal requester, the
CS22210 will keep Clock Enable (CKE) signal low to cause the SDRAM to stay in power
down mode. Once a memory request is active, the CS22210 will assert CKE high to cause
the SDRAM to come out of power down mode. Typically, this can reduce memory power
consumption by up to 50%.
In ROM configuration, firmware for CS22210 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. The
ROM can be re-flashed allowing for software upgrades.
3.5 PCI Controller Interface
Embedded in the CS22210 is a PCI 2.1 / PCI 2.2 fully compliant master/target 32 bit data
interface including power management support (PME signal). The communication buffer
logic was designed to be flexible and generic to both the PC software and ARM firmware.
The control communication between PCI and ARM uses a mailbox mechanism. The PCI
writes data into a Dword mailbox register whereby an interrupt is generated to the ARM. The
ARM reads this register to get the control information whereby an interrupt is generated to the
PCI. The same is true from the ARM writing to a ARM mailbox register.
PCI data transfer is supported by a DMA Control Block (DCB). The DCB is configured by the
ARM, allowing the ARM to control how often it is interrupted. PCI data transfers are done by
the PCI master and the DCB offloading CPU overhead.
3.6 USB Interface
Embedded within the CS22210 is a full speed USB 1.1 compliant device interface. The
device supports from 1 to 16 endpoints and is completely programmable via firmware
download or external EEPROM.
All “setup” commands are passed to the system processor for interpretation. The device also
contains a DMA engine to transfer arbitrary amounts of data to and from main memory before
interrupting the system processor.
CS22210 PCI/USB Wireless Controller
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