psd835g2 STMicroelectronics, psd835g2 Datasheet - Page 76

• Manufacturer Part Number: psd835g2
• Description: Configurable Memory System On A Chip For 8-bit Microcontrollers
• Manufacturer: STMicroelectronics

I/O ports
17.2
Figure 25. General I/O port architecture
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ADDRESS
ALE
MACROCELL OUTPUTS
EXT CS
WR
Port operating modes
The I/O ports have several modes of operation. Some modes can be defined using
PSDabel, some by the MCU writing to the registers in CSIOP space, and some by both. The
modes that can only be defined using PSDsoft must be programmed into the device and
cannot be changed unless the device is reprogrammed. The modes that can be changed by
the MCU can be done so dynamically at run-time. The PLD I/O, Data port, Address Input,
Peripheral I/O and MCU Reset modes are the only modes that must be defined before
programming the device. All other modes can be changed by the MCU at run-time.
Table 14
where the different modes are configured. Each of the port operating modes are described
in the following sections.
ENABLE PRODUCT TERM ( .OE )
WR
WR
summarizes which modes are available on each port.
CONTROL REG.
CPLD-INPUT
DATA OUT
READ MUX
DIR REG.
G
D
D
D
D
REG.
P
D
B
Q
Q
Q
Q
DATA IN
DATA OUT
ADDRESS
OUTPUT
SELECT
OUTPUT
MUX
ENABLE OUT
MACROCELL
Table 17
INPUT
shows how and
PSD835G2
PORT PIN
AI02885