psd4235g2 STMicroelectronics, psd4235g2 Datasheet - Page 71

• Manufacturer Part Number: psd4235g2
• Description: Flash In-system Programmable Isp Peripherals For 16-bit Mcus 5v Supply
• Manufacturer: STMicroelectronics

PSD4235G2
19.2
Figure 19. An example of a typical 16-bit non-multiplexed bus interface
19.3
RESET
MCU
PSD interface to a non-multiplexed 8-bit bus
Figure 19
and a PSD4235G2. The address bus is connected to the ADIO Port, and the data bus is
connected to Ports F and G. Ports F and G are in tri-state mode when the PSD is not
accessed by the MCU. Should the system address bus exceed sixteen bits, Ports A, B, or C
may be used for additional address inputs.
Data Byte Enable reference
MCUs have different data byte orientations.
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.'
Table 35.
BHE
BHE
ALE
WR
RD
0
0
1
shows an example of a system using a MCU with a 16-bit non-multiplexed bus
16-bit data bus with BHE
D [ 15:0 ]
A [ 15:0 ]
A0
0
1
0
Odd Byte
Odd Byte
—
PSD
WR ( CNTRL0 )
RD ( CNTRL1 )
BHE ( CNTRL2 )
RST
ALE ( PD0 )
PORT D
PORT
ADIO
D15-D8
Table 35
PORT
PORT
PORT
to
G
F
A
Table 38
Even Byte
—
Even Byte
show how the PSD4235G2
( OPTIONAL )
D[15:8] 1
D [ 7:0 ]
A [ 23:16 ]
MCU bus interface
D7-D0
AI04929
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