MC68181 Datasheet, PDF (87/119 Pages) Freescale Semiconductor, Inc – Advance Information ROAMING FLEX chip SIGNAL PROCESSOR

Freescale Semiconductor, Inc.
MC68181
Decoder-to-Host Packet Descriptions
DECODER-TO-HOST PACKET DESCRIPTIONS
The following sections describe the packets of information that will be sent from the
FLEX chip IC to the host. In all cases the packets are sent MSB first (Bit 7 of byte 3 =
Bit 31 of the packet = MSB). The FLEX chip IC decides what data should be sent to the
host. If the FLEX chip IC is disabled through the checksum feature (see Checksum
Packet on page B-6), the Part ID Packet will be sent. Data Packets relating to data
received over the air are buffered in the 32 packet transmit buffer. The Data Packets
include Block Information Word Packets, Address Packets, Vector Packets, and
Message Packets.
If the FLEX chip IC is enabled and a receiver shutdown packet is pending, the
receiver shutdown packet will be sent. If there is no receiver shutdown packet
pending, but there is a roaming status packet pending, the roaming status packet will
be sent. If neither the receiver shutdown packet nor the roaming status packet is
pending and there is data in the transmit buffer, a packet from the transmit buffer
will be sent. Otherwise, the FLEX chip IC will send the Status Packet (which is not
buffered). In the event of a buffer overflow, the FLEX chip IC will automatically stop
decoding and clear the buffer.
It is recommended that the Host be designed to empty the FIFO buffer every block
with enough time left over to read a status packet. This would ensure that any
applicable Status Packet would be received within 1 block of the new status being
available.
Part ID Register
32
Receive Shutdown Register ³²
Roaming Status Register ³²
32 × 32 Data Packet
FIFO Transmit
32
Buffer
32
SPI Transmit Register
MISO
Status Register
32
Figure B-5 FLEX chip IC SPI Transmit Functional Block Diagram
AA1233
MOTOROLA
MC68181 Technical Data Sheet
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