Rainbow Electronics ATmega128RFA1 - Manual (Page 190)

190
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