ATMEGA323-8AI Atmel, ATMEGA323-8AI Datasheet - Page 140

• Manufacturer Part Number: ATMEGA323-8AI
• Description: IC AVR MCU 32K 8MHZ IND 44TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA323-8AI

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 8MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 32
• Program Memory Size: 32KB (16K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 1K x 8
• Ram Size: 2K x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 44-TQFP, 44-VQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: ATMEGA3238AI

Port B As General Digital I/O
Alternate Functions of Port B
140
ATmega323(L)
The Port B Input Pins address – PINB – is not a register, and this address enables
access to the physical value on each Port B pin. When reading PORTB, the Port B Data
Latch is read, and when reading PINB, the logical values present on the pins are read.
All eight bits in Port B are equal when used as digital I/O pins. PBn, General I/O pin: The
DDBn bit in the DDRB Register selects the direction of this pin, if DDBn is set (one), PBn
is configured as an output pin. If DDBn is cleared (zero), PBn is configured as an input
pin. If PORTBn is set (one) when the pin configured as an input pin, the MOS pull up
resistor is activated. To switch the pull up resistor off, the PORTBn has to be cleared
(zero), the pin has to be configured as an output pin, or the PUD bit has to be set. The
Port B pins are tri-stated when a reset condition becomes active, even if the clock is not
running.
Table 50. DDBn Effects on Port B Pins
Note:
The alternate pin configuration is as follows:
• SCK – Port B, Bit 7
SCK: Master Clock output, Slave Clock input pin for SPI channel. When the SPI is
enabled as a Slave, this pin is configured as an input regardless of the setting of DDB7.
When the SPI is enabled as a Master, the data direction of this pin is controlled by
DDB7. When the pin is forced to be an input, the pull-up can still be controlled by the
PORTB7 bit. See the description of the SPI port for further details.
• MISO – Port B, Bit 6
MISO: Master Data input, Slave Data output pin for SPI channel. When the SPI is
enabled as a Master, this pin is configured as an input regardless of the setting of
DDB6. When the SPI is enabled as a Slave, the data direction of this pin is controlled by
DDB6. When the pin is forced to be an input, the pull-up can still be controlled by the
PORTB6 bit. See the description of the SPI port for further details.
• MOSI – Port B, Bit 5
MOSI: SPI Master Data output, Slave Data input for SPI channel. When the SPI is
enabled as a Slave, this pin is configured as an input regardless of the setting of DDB5.
When the SPI is enabled as a Master, the data direction of this pin is controlled by
DDB5. When the pin is forced to be an input, the pull-up can still be controlled by the
PORTB5 bit. See the description of the SPI port for further details.
DDBn
0
0
0
1
1
1. n: 7,6…0, pin number.
PORTBn
0
1
1
0
1
(in SFIOR)
PUD
X
0
1
X
X
Output
Output
Input
Input
Input
I/O
(1)
Pull-up
Yes
No
No
No
No
Comment
Tri-state (Hi-Z)
Tri-state (Hi-Z)
PBn will Source Current if Ext. Pulled
Low.
Push-Pull Zero Output
Push-Pull One Output
1457G–AVR–09/03