IEEE 802.11b MAC and Baseband for Supporting Standard Rates Up to 11 Mbps
Wireless Interface Following the IEEE 802.11b Standard
Wireless LAN MAC Unit with ARM7TDMI® RISC Processor
Integrated 128-byte Transmit and 128-byte Receive FIFOs for Wireless MAC
Layer Functions
Delivers Standard Wireless Networking to Any Host that Supports a Full-speed
(12 Mbps) USB Interface
The On-chip Boot-ROM Implements the Device Upgrade Protocol (DFU) Spec Making
the AT76C505 Ideal for Low-cost Terminal Adaptors without Requiring External
Program Flash Since the Host Driver Downloads the Code During the Start-up Phase
Support of an External Serial EEPROM for Configuration Settings
Glueless SRAM Interface for All MAC Operations, Supporting Up to 1M Byte of
External Memory
Integrated 6K x 32-bit Internal SRAM, Used for Fast Program Code Execution and
Temporary Storage of Data
Glueless Flash Memory Interface, Supporting Up to 1M Byte of Nonvolatile Memory for
Permanent Storage of Program Code
Wired Equivalency Privacy (WEP) in Hardware Supporting 64-bit and 128-bit
Hardware Implementation of Time Critical MAC Functions by the MAC Support Unit
(MSU) Guarantees Maximum Robustness
The WLAN and Inter-networking Functions Can Be Changed and Updated Easily to
New Requirements Since They are Implemented in Microcode
Supports 11 Mbps Rates with Automatic Fallback to 5.5, 2 and 1 Mbps
128-ball CABGA Package
Low-voltage 3.3V Operation
SPI Interface and 8 GPIO Pins
Baseband Supports Antenna Diversity Algorithm
Baseband Supports Japan Filter
Baseband Supports Differential or Single-ended I- and Q-Baseband Signals
Integrated 802.11b Baseband Processor
Media Access
(MAC) and
Baseband with
USB Interface
Block Diagram
SPI Interface
USB Interface
Common Memory
Interface Controller
Boot ROM
MAC Support
Unit (MSU)
Note: This is a summary datasheet. A complete document is available
under NDA. For more information, please contact your local Atmel sales
The AT76C505 is a single-chip baseband controller that can handle IEEE 802.11b standard compliant data rates of up to 11 Mbps and provides all processing and functionality
needed for the MAC protocol of IEEE 802.11b. The AT76C505 is a full-speed USB
device that can support up to four configurable Endpoints (EP) plus one Control EP. The
AT76C505 USB interface can support Suspend and Resume bus condition for saving
power during host idle periods.
Besides the USB interface unit, the AT76C505 chip contains a WEP engine block, a
MAC Support Unit (MSU), a 802.11b baseband controller, a memory controller and the
ARM® subsystem consisting of an Interrupt Controller, two 32-bit timers and an address
decoder unit.
The ARM7TDMI core supports two alternative instruction sets. Powerful 32-bit code can
be executed by the processor in ARM operating mode. However, a 16-bit instruction
subset is also available in Thumb® mode. Thumb mode can be selected to exploit full
processor power with limited external memory resources. Note that ARM7TDMI operating mode can be changed at run time with negligible overhead.
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