
SMSC DS – FDC37N958FR
Page 226
Rev. 09/01/99
BIT 5 STS
When in slave receiver mode, this flag is
asserted when an externally generated STOP
condition is detected (used only in slave receiver
mode).
BIT 4 BER
Bus error; a misplaced START or STOP
condition has been detected. Resets nBB (to
logic “1”; inactive), sets PIN = “0” (active).
BIT 3
LRB/AD0
Last Received Bit or Address 0 (general call) bit.
This status bit serves a dual function, and is
valid only while PIN=0:
1. LRB holds the value of the last received bit
over the ACCESS.bus while AAS=0 (not
addressed as slave). Normally this will be
the value of the slave acknowledgment; thus
checking for slave acknowledgment is done
via testing of the LRB.
2. ADO; when AAS = “1” (Addressed as slave
condition) the ACCESS.bus controller has
been addressed as a slave. Under this
condition, this bit becomes the AD0 bit and
will be set to logic “1” if the slave address
received was the ‘general call’ (00h)
address, or logic “0” if it was the
ACCESS.bus
controller’s
address.
own
slave
BIT 2 AAS
Addressed As Slave bit. Valid only when PIN=0.
When acting as slave receiver, this flag is set
when
an
incoming
address
over
the
ACCESS.bus matches the value in own address
register S0’ (shifted by one bit) or if the
ACCESS.bus ‘general call’ address (00h) has
been received (‘general call’ is indicated when
AD0 status bit is also set to logic “1”).
BIT 1 LAB
Lost Arbitration Bit. This bit is set when, in multi-
master operation, arbitration is lost to another
master on the ACCESS.bus.
BIT 0 nBB
Bus Busy bit. This is a read-only flag indicating
when the ACCESS.bus is in use. A zero
indicates that the bus is busy, and access is not
possible. This bit is set/reset (logic “1”/logic “0”)
by Start/Stop conditions.
OWN ADDRESS REGISTER S0’
When the chip is addressed as slave, this
register must be loaded with the 7-bit
ACCESS.bus address to which the chip is to
respond. During initialization, the own address
register S0’ must be written to, regardless
whether it is later used. The Addressed As
Slave (AAS) bit in status register S1 is set when
this address is received (the value in S0 is
compared with the value in S0’). Note that the
S0 and S0’ registers are offset by one bit; hence,
programming the own address register S0’ with
a value of 55h will result in the value AAh being
recognized as the chip’s ACCESS.bus slave
address.
After reset, S0’ has default address 00h.