atmega32c1 ATMEL Corporation, atmega32c1 Datasheet - Page 64

• Manufacturer Part Number: atmega32c1
• Description: Atmega32m1 Automotive 8-bit Avr Microcontroller With 32k/64k Bytes In-system Programmable Flash
• Manufacturer: ATMEL Corporation

9.2.5
64
ATmega32/64/M1/C1
Digital Input Enable and Sleep Modes
values are read back again, but as previously discussed, a nop instruction is included to be able
to read back the value recently assigned to some of the pins.
Note:
As shown in
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
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
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 modes, as the clamping in these sleep modes produces the requested
logic change.
Assembly Code Example
C Code Example
TABLE 2.
unsigned char i;
...
; Define pull-ups and set outputs high
; Define directions for port pins
ldi
ldi
out
out
; Insert nop for synchronization
nop
; Read port pins
in
...
...
/* 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*/
_NOP();
/* Read port pins */
i = PINB;
...
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.
Figure
r16, (1<<PB7)|(1<<PB6)|(1<<PB1)|(1<<PB0)
r17, (1<<DDB3)|(1<<DDB2)|(1<<DDB1)|(1<<DDB0)
PORTB, r16
DDRB, r17
r16, PINB
9-2, the digital input signal can be clamped to ground at the input of the
(1)
“Alternate Port Functions” on page
CC
65.
/2.
7647A–AVR–02/08