User`s guide

Aironet Wireless Communications, Inc. 7-16 Confidential and Proprietary
Basic FID Access
Memory items consist of:
FIDs - Frame Identifiers (transmit/receive packets or allocated memory)
RIDs - Resource Identifiers (configuration items)
FID/RID are accessed using three I/O registers: selector, offset, data.
The first register is the selector register, which chooses the desired FID/RID. The second register is the
offset register, which selects the position within the FID/RID. The third register is the data register
which allows reads and writes to the FID/RID. Successive reads and writes go to sequential locations
within the FID/RID.
Valid FIDS are obtained from the TxAllocFid, TxComplFID, or RxFID I/O-registers, or possibly in
response to a successful command.
A RID (Resource Identifier) may also be used in the Selector fields. These are predefined selectors from
0xFF00 to 0xFFFF. The RIDs are used to access configuration items.
Additional information on FID access is provided in the section on “Memory (FID/RID) Access”.
FID Management Register Descriptions
These registers provide the Frame Identifier (FID) of the PC4500/4800 buffers that become available as
result of an asynchronous process. A specific FID value is only valid when read while availability is
signaled and before that availability is acknowledged. In other words, you must read and process RxFID
(including reading it) before issuing EvAckRx.
RxFID Register (I/O offset 0x20)
Bit #1514131211109876543210
Name Received FID
This register is used to read the FID of received frame structure buffers. This FID becomes available as a
result of an asynchronous packet reception. The received FID availability is signaled by the EvStat.Rx
bit. A subsequent received FID can only become available after availability of the current FID is
acknowledged with EvAck.Rx bit.
TxAllocFID Register (I/O offset 0x22)
Bit #1514131211109876543210
Name Allocated Transmit FID
This register is used to read the FID of transmit frame structure buffer. This FID becomes available as a
result of the asynchronous allocation process initiated by an Allocate command. Allocated transmit FID
availability is signaled by the EvStat.Alloc bit. A subsequent allocated transmit FID can only become
available after availability of the current FID is acknowledged with EvAck.Alloc bit.