73K224BL
V.22bis, V.22, V.21, Bell 212A, 103
Single-Chip Modem w/ Integrated Hybrid
DATA SHEET
PARALLEL MICROPROCESSOR INTERFACE (continued)
NAME
PIN
TYPE
DESCRIPTION
WR
14
I
WRITE: A low on this informs the 73K224BL 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 MICROPROCESSOR CONTROL INTERFACE MODE
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 73K224BL 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 for 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 73K224BL 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 register address.
Page: 6 of 33
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