st92f120 STMicroelectronics, st92f120 Datasheet - Page 15

• Manufacturer Part Number: st92f120
• Description: 8/16-bit Flash Mcu Family With Ram, Eeprom And J1850 Blpd
• Manufacturer: STMicroelectronics

How to Configure the I/O Ports
To configure the I/O ports, use the information in
Table
ble in the I/O Ports Chapter (See
Input Note = the hardware characteristics fixed for
each port line in
– If Input note = TTL/CMOS, either TTL or CMOS
– If Input note = Schmitt trigger, selecting CMOS
Alternate Functions (AF) = More than one AF
cannot be assigned to an I/O pin at the same time:
An alternate function can be selected as follows.
AF Inputs:
– AF is selected implicitly by enabling the corre-
AF Outputs or Bidirectional Lines:
– In the case of Outputs or I/Os, AF is selected ex-
input level can be selected by software.
or TTL input by software has no effect, the input
will always be Schmitt Trigger.
sponding peripheral. Exception to this are A/D in-
puts which must be explicitly selected as AF by
software.
plicitly by software.
3,
Table 4
Table
and the Port Bit Configuration Ta-
3.
page
120).
Example 1: SCI input
AF: SIN0, Port: P5.2, Input note: Schmitt Trigger.
Write the port configuration bits:
P5C2.2=1
P5C1.2=0
P5C0.2 =1
Enable the SCI peripheral by software as de-
scribed in the SCI chapter.
Example 2: SCI output
AF: SOUT0, Port: P5.3, Output note:
Push-Pull/OD.
Write the port configuration bits (for AF OUT PP):
P5C2.3=0
P5C1.3=1
P5C0.3 =1
Example 3: External Memory I/O
AF: A0/D0, Port : P0.0, Input Note: TTL/CMOS
Write the port configuration bits:
P0C2.0=1
P0C1.0=1
P0C0.0 =1
Example 4: Analog input
AF: A0IN0, Port : 7.0, Input Note: does not apply
to analog input
Write the port configuration bits:
P7C2.0=1
P7C1.0=1
P7C0.0 =1
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