ST10F280 datasheet(82/186 Pages) STMICROELECTRONICS

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ST10F280

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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 below, 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 dou-

ble-register mode. In these modes, unlike in com-

pare 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 out-

put 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 con-

nected 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 func-

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

external interrupt inputs (200 ns 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 below summarizes the alternate func-

tions of Port 2.

Figure 33 : Port 2 I/O and Alternate Functions

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 Timer T7 Ext. Count Input

Port 2

Alternate Function

General Purpose

Input / Output

CAPCOM1

Capture Input / Compare Output

Fast External

Interrupt Input

CAPCOM2

Timer T7 Input