psd511b1 STMicroelectronics, psd511b1 Datasheet - Page 33

• Manufacturer Part Number: psd511b1
• Description: Low Cost Field Programmable Microcontroller Peripherals
• Manufacturer: STMicroelectronics

Bus
Interface
(Cont.)
30
PSD5XX Family
Table 7. 16-Bit Data Bus With BHE
Table 9. 16-Bit Data Bus With SIZ0, A0
Table 10. 16-Bit Data Bus With UDS, LDS
Table 6. 8-Bit Data Bus
Table 8. 16-Bit Data Bus With WRH and WRL
9.2.4 Data Byte Enable
Microcontrollers have different data byte orientations with regard to the data bus. The
following tables show how the PSD5XX handles the byte enable under different bus
configurations. Even byte refers to locations with address A0 equal to “0”, and odd byte as
locations with A0 equal to “1”.
9.2.3 PSD5XX Interface To Non-Multiplexed Bus
Figure 16 shows a PSD5XX interfacing to a microcontroller with a non-multiplexed
address/data bus. The address bus is connected to the ADIO Port, and the data bus is
connected to Port C and/or Port D, depending on the bus width. There is no need for the
ADIO Port to latch the address internally, but the user is offered the option to do so in the
PSD5XX PSDsoft Software. The data ports are in tri-state mode when the PSD5XX is not
accessed by the microcontroller.
WRH
BHE
SIZ0
LDS
BHE
0
0
1
0
0
1
0
1
1
0
1
0
X
X
UDS (A0)
WRL
A0
A0
0
1
0
0
1
0
0
0
1
0
0
1
A0
0
1
Even Byte
Odd Byte
D7 – D0
D15 – D8
D15 – D8
D15 – D8
D15 – D8
Even byte
Even byte
Even byte
Even byte
Odd byte
Odd byte
Odd byte
Odd byte
–
–
–
–
Even byte
Even byte
Even byte
Even byte
Odd byte
Odd byte
D7 – D0
Odd byte
Odd byte
D7 – D0
D7 – D0
D7 – D0
–
–
–
–