ST92F124/F150/F250 - I/O PORTS
INPUT/OUTPUT BIT CONFIGURATION (Cont’d)
Figure 81. Basic Structure of an I/O Port Pin
I/O PIN
PUSH-PULL
TRISTATE
OPEN DRAIN
WEAK PULL-UP
FROM
PERIPHERAL
OUTPUT
OUTPUT SLAVE LATCH
ALTERNATE
FUNCTION
INPUT
OUTPUT
BIDIRECTIONAL
OUTPUT
OUTPUT MASTER LATCH
TTL / CMOS
(or Schmitt Trigger)
TO PERIPHERAL
INPUTS AND
INTERRUPTS
INPUT
BIDIRECTIONAL
ALTERNATE
FUNCTION
INPUT LATCH
Figure 82. Input Configuration
I/O PIN
INTERNAL DATA BUS
Figure 83. Output Configuration
I/O PIN
TRISTATE
OUTPUT SLAVE LATCH
TTL / CMOS
(or Schmitt Trigger)
TO PERIPHERAL
INPUTS AND
INTERRUPTS
OPEN DRAIN
PUSH-PULL
OUTPUT SLAVE LATCH
TTL
(or Schmitt Trigger)
TO PERIPHERAL
INPUTS AND
INTERRUPTS
OUTPUT MASTER LATCH
INPUT LATCH
INTERNAL DATA BUS
n
n
OUTPUT MASTER LATCH
INPUT LATCH
INTERNAL DATA BUS
n
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