PSD833F3A-20UI View Datasheet(PDF) - STMicroelectronics
Part Name
Description
Manufacturer
PSD833F3A-20UI Datasheet PDF : 128 Pages
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MCU bus interface
PSD8XXFX
15.1
PSD interface to a multiplexed 8-bit bus
Figure 18 shows an example of a system using a MCU with an 8-bit multiplexed bus and a
PSD. The ADIO port on the PSD is connected directly to the MCU address/data bus.
Address Strobe (ALE/AS, PD0) latches the address signals internally. Latched addresses
can be brought out to port A or B. The PSD drives the ADIO data bus only when one of its
internal resources is accessed and Read Strobe (RD, CNTL1) is active. Should the system
address bus exceed sixteen bits, ports A, B, C, or D may be used as additional address
inputs.
Figure 18. An example of a typical 8-bit multiplexed bus interface
t(s) MCU
te Produc WR
le RD
o BHE
Obs ALE
AD [7:0]
A[ 15:8]
ct(s) - RESET
PSD
ADIO
PORT
WR (CNTRL0)
RD (CNTRL1)
BHE (CNTRL2)
RST
PORT
A
PORT
B
PORT
C
ALE (PD0)
PORT D
A[7: 0]
(OPTIONAL)
A[15: 8]
(OPTIONAL)
AI02878C
Obsolete Produ 15.2
PSD interface to a non-multiplexed 8-bit bus
Figure 19 shows an example of a system using a MCU with an 8-bit non-multiplexed bus
and a PSD. The address bus is connected to the ADIO port, and the data bus is connected
to port A. port A is in tri-state mode when the PSD is not accessed by the MCU. Should the
system address bus exceed sixteen bits, ports B, C, or D may be used for additional address
inputs.
15.3
Data Byte Enable reference
MCUs have different data byte orientations. Table 18 shows how the PSD interprets
byte/word operations in different bus WRITE configurations. Even-byte refers to locations
with address A0 equal to '0' and odd byte as locations with A0 equal to ’1.’
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Doc ID 7833 Rev 7
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