ST72104G2M7 데이터 시트보기 (PDF) - STMicroelectronics

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ST72104G2M7

8-BIT MCU WITH SINGLE VOLTAGE FLASH MEMORY, ADC, 16-BIT TIMERS, SPI, I2C INTERFACES

STMicroelectronics 

ST72104G, ST72215G, ST72216G, ST72254G

I/O PORTS (Cont’d)

CAUTION: The alternate function must not be ac-

tivated as long as the pin is configured as input

with interrupt, in order to avoid generating spurious

interrupts.

Analog alternate function

When the pin is used as an ADC input, the I/O

must be configured as floating input. The analog

multiplexer (controlled by the ADC registers)

switches the analog voltage present on the select-

ed pin to the common analog rail which is connect-

ed to the ADC input.

It is recommended not to change the voltage level

or loading on any port pin while conversion is in

progress. Furthermore it is recommended not to

have clocking pins located close to a selected an-

alog pin.

WARNING: The analog input voltage level must

be within the limits stated in the absolute maxi-

mum ratings.

9.3 I/O PORT IMPLEMENTATION

The hardware implementation on each I/O port de-

pends on the settings in the DDR and OR registers

and specific feature of the I/O port such as ADC In-

put or true open drain.

Switching these I/O ports from one state to anoth-

er should be done in a sequence that prevents un-

wanted side effects. Recommended safe transi-

tions are illustrated in Figure 22 Other transitions

are potentially risky and should be avoided, since

they are likely to present unwanted side-effects

such as spurious interrupt generation.

Figure 22. Interrupt I/O Port State Transitions

01

00

INPUT

floating/pull-up

interrupt

INPUT

floating

(reset state)

10

OUTPUT

open-drain

11

OUTPUT

push-pull

XX = DDR, OR

The I/O port register configurations are summa-

rized as follows.

Interrupt Ports

PA7, PA5, PA3:0, PB7:0, PC5:0 (with pull-up)

MODE

floating input

pull-up interrupt input

open drain output

push-pull output

DDR OR

0

0

0

1

1

0

1

1

True Open Drain Interrupt Ports

PA6, PA4 (without pull-up)

MODE

floating input

floating interrupt input

open drain (high sink ports)

DDR OR

0

0

0

1

1

X

Table 8. Port Configuration

Port

Pin name

Port A

Port B

Port C

PA7

PA6

PA5

PA4

PA3:0

PB7:0

PC7:0

Inpu t (DDR = 0)

OR = 0

floating

floating

floating

floating

floating

floating

floating

OR = 1

pull-up interrupt

floating interrupt

pull-up interrupt

floating interrupt

pull-up interrupt

pull-up interrupt

pull-up interrupt

Output (DDR = 1)

OR = 0

OR = 1

open drain

push-pull

true open-drain

open drain

push-pull

true open-drain

open drain

push-pull

open drain

push-pull

open drain

push-pull

High-Sink

Yes

No

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