ST10F269 datasheet(67/160 Pages) STMICROELECTRONICS

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ST10F269

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The direction of the pin should be set to output by

the user, otherwise the pin will be in the

high-impedance state and will not reflect the state

of the output latch.

As can be seen from the port structure in Figure

26, the user software always has free access to

the port pin even when it is used as a compare

output. This is useful for setting up the initial level

of the pin when using compare mode 1 or the

double-register mode. In these modes, unlike in

compare mode 3, the pin is not set to a specific

value when a compare match occurs, but is

toggled instead.

When the user wants to write to the port pin at the

same time a compare trigger tries to clock the

output latch, the write operation of the user

software has priority. Each time a CPU write

access to the port output latch occurs, the input

multiplexer of the port output latch is switched to

the line connected to the internal bus. The port

output latch will receive the value from the internal

bus and the hardware triggered change will be

lost.

As all other capture inputs, the capture input

function of pins P2.15...P2.0 can also be used as

external interrupt inputs (200ns sample rate at

40MHz CPU clock).

The upper eight Port 2 lines (P2.15...P2.8) also

can serve as Fast External Interrupt inputs from

EX0IN to EX7IN (Fast external interrupt sampling

rate is 25ns at 40MHz CPU clock).

P2.15 in addition serves as input for CAPCOM2

timer T7 (T7IN). The Table 15 summarizes the

alternate functions of Port 2.

Table 15 : Alternate Functions of Port 2

Port 2 Pin

Alternate Function a)

Alternate Function b)

Alternate Function c)

P2.0

P2.1

P2.2

P2.3

P2.4

P2.5

P2.6

P2.7

P2.8

P2.9

P2.10

P2.11

P2.12

P2.13

P2.14

P2.15

CC0IO

CC1IO

CC2IO

CC3IO

CC4IO

CC5IO

CC6IO

CC7IO

CC8IO

CC9IO

CC10IO

CC11IO

CC12IO

CC13IO

CC14IO

CC15IO

EX0IN

Fast External Interrupt 0 Input

EX1IN

Fast External Interrupt 1 Input

EX2IN

Fast External Interrupt 2 Input

EX3IN

Fast External Interrupt 3 Input

EX4IN

Fast External Interrupt 4 Input

EX5IN

Fast External Interrupt 5 Input

EX6IN

Fast External Interrupt 6 Input

EX7IN

Fast External Interrupt 7 Input

T7IN T7 External Count Input

Figure 25 : Port 2 I/O and Alternate Functions

Port 2

Alternate Function

General Purpose

Input / Output

CAPCOM1

Capture Input / Compare Output

Fast External

Interrupt Input

CAPCOM2

Timer T7 Input