EM77950
BB Controller
Bit 4: LOCK
This signals whether a Preamble was identified or is still searching.
When the flag is “0”, the receiver is searching for Preamble.
When the flag is “1” a Preamble was identified. If a packet was discarded for
any reason, the LOCK flag goes to 1.
Bit 5: BIT_ERROR
This flag indicate that there was some error in the received package. The
packet was not received according the expected timing specifications.
The packet can still pass CRC verification.
Bit 6: TX_UF
This flag is set whenever the MCU reads a byte from an empty TX_FIFO.
This flag indicates abnormal end of packet transmission. The MCU
transmitter’s state machine has expected to find a valid byte in the TX_FIFO
according to the packet size, but it found an empty TX_FIFO. When this event
occurs, the TX_EMPTY interrupt is invoked and TX_UF (underflow) flag is set
to ‘1’.
This flag is set by hardware and cleaned by MCU. It is cleaned whenever the
MCU read the SSR register.
Default Value: 0x04.
8.3.15 Packet Size Register (PSR)
This is a read and a write register.
It contains the Packet Size in byte units. When working in fixed size packets (see
Control Bit-1), the size will be fixed for all types of packets.
The size in PSR excludes 2 bytes of Preamble and 2, 1 or 0 bytes of CRC.
Default Value: 0x00.
8.3.16 Carrier Sense Register (CSR)
This is both a read and a write register.
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
ZERO
CNT.3
ZERO
CNT.2
ZERO
CNT.1
ZERO
CNT.0
ONE
ONE
ONE
ONE
CSR
CNT.3
CNT.2
CNT.1
CNT.0
Bits 0-3: ONE_CNT [0:3]
The number of successive “1” bits that set the carrier sense high.
Bits 4-7: ZERO_CNT [0:3]
The number of successive “0” bits that reset the carrier sense (CS=’0’).
Default Value: 0x44
62 •
Product Specification (V1.0) 10.09.2007
(This specification is subject to change without further notice)
ELAN [ ELAN MICROELECTRONICS CORP ]
