73K222BL
V.22, V.21, Bell 212A, 103 Single-Chip
Modem with Integrated Hybrid
DATA SHEET
PARALLEL CONTROL INTERFACE (continued)
NAME
PIN
TYPE
DESCRIPTION
WR
14
I
Write. A low on this pin informs the 73K222BL that data is available on
AD0-AD7 for writing into an internal register. Data is latched on the rising
edge of WR. No data is written unless both WR and the latched CS are
low.
SERIAL CONTROL INTERFACE
NAME
PIN
TYPE
DESCRIPTION
AD0-AD2
5-7
I
Register Address Selection. These lines carry register addresses and
should be valid during any read or write operation.
DATA (AD7)
12
15
I/O
I
Serial Control Data. Data for a read/write operation is clocked in or out on
the falling edge of the EXCLK pin. The direction of data flow is controlled
by the RD pin. RD low outputs data. RD high inputs data.
RD
Read. A low on this input informs the 73K222BL that data or status
information is being read by the processor. The falling edge of the RD
signal will initiate a read from the addressed register. The RD signal must
continue fort eight falling edges of EXCLK in order to read all eight bits of
the referenced register. Read data is provided LSB first. Data will not be
output unless the RD signal is active.
WR
14
I
Write. A low on this input informs the 73K222BL that data or status
information has been shifted in through the DATA pin and is available for
writing to an internal register. The normal procedure for a write is to shift
in data LSB first on the DATA pin for eight consecutive falling edges of
EXCLK and then to pulse WR low. Data is written on the rising edge of
WR.
NOTE: The serial control mode is provided by tying ALE high and CS low. In this configuration AD7 becomes
DATA and AD0, AD1 and AD2 become the address only.
Page: 6 of 26
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