Rainbow-electronics ATmega128RFA1 Instrukcja Użytkownika Pobierz pdf (Strona 190)

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8266A-MCU Wireless-12/09

ATmega128RFA1

Assembly Code Example

(1)

…

; Define pull-ups and set outputs high

; Define directions for port pins

ldi r16,(1<<PB7)|(1<<PB6)|(1<<PB1)|(1<<PB0)

ldi r17,(1<<DDB3)|(1<<DDB2)|(1<<DDB1)|(1<<DDB0)

out PORTB,r16

out DDRB,r17

; Insert nop for synchronization

nop

; Read port pins

in r16,PINB

…

C Code Example

unsigned char i;

…

/* Define pull-ups and set outputs high */

/* Define directions for port pins */

PORTB = (1<<PB7)|(1<<PB6)|(1<<PB1)|(1<<PB0);

DDRB = (1<<DDB3)|(1<<DDB2)|(1<<DDB1)|(1<<DDB0);

/* Insert nop for synchronization*/

__no_operation();

/* Read port pins */

i = PINB;

…

Note:

1. For the assembly program, two temporary registers are used to minimize the time

from pull-ups are set on pins 0, 1, 6, and 7, until the direction bits are correctly set,

defining bit 2 and 3 as low and redefining bits 0 and 1 as strong high drivers.

14.2.6 Digital Input Enable and Sleep Modes

As shown in Figure 14-2 on page 187, the digital input signal can be clamped to ground

at the input of the Schmitt-Trigger. The signal denoted SLEEP in the figure, is set by the

MCU Sleep Controller in Power-down mode, Power-save mode, and Standby mode to

avoid high power consumption if some input signals are left floating, or have an analog

signal level close to V

DEVDD

/2.

SLEEP is overridden for port pins enabled as external interrupt pins. If the external

interrupt request is not enabled, SLEEP is active also for these pins. SLEEP is also

overridden by various other alternate functions as described in "Alternate Port

Functions" on page 191.

If a logic high level (“one”) is present on an asynchronous external interrupt pin

configured as “Interrupt on Rising Edge, Falling Edge, or Any Logic Change on Pin”

while the external interrupt is not enabled, the corresponding External Interrupt Flag will

be set when resuming from the above mentioned Sleep mode, as the clamping in these

sleep mode produces the requested logic change.

14.2.7 Unconnected Pins

If some pins are unused, it is recommended to ensure that these pins have a defined

level. Even though most of the digital inputs are disabled in the deep sleep modes as

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