ATtiny28L Atmel Corporation, ATtiny28L Datasheet - Page 27

• Manufacturer Part Number: ATtiny28L
• Manufacturer: Atmel Corporation

Specifications of ATtiny28L

• Flash (kbytes): 2 Kbytes
• Pin Count: 28
• Max. Operating Frequency: 4 MHz
• Cpu: 8-bit AVR
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 11
• Ext Interrupts: 10
• Usb Speed: No
• Usb Interface: No
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 0.03
• Self Program Memory: NO
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.8 to 5.5
• Operating Voltage (vcc): 1.8 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 1
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

Port B
Port B as General Digital Input All eight pins in Port B have equal functionality when used as digital input pins.
Alternate Functions of Port B
1062F–AVR–07/06
Port B is an 8-bit input port.
One I/O address location is allocated for the Port B Input Pins – PINB, $16. The Port B
Input Pins address is read-only.
All port pins have pull-ups that can be switched on for all Port B pins simultaneously. If
any of the Port B special functions is enabled, the corresponding pull-up(s) is disabled.
When pins PB0 to PB7 are externally pulled low, they will source current (I
nal pull-up resistors are activated.
The Port B pins with alternate functions are shown in Table 11.
Table 11. Port B Pin Alternate Functions
PBn, general input pin: To switch the pull-up resistors on, the PLUPB bit in the MCUCS
register must be set (one). This bit controls the pull-up on all Port B pins. To turn the
pull-ups off, this bit has to be cleared (zero). Note that if any Port B pins are used for
alternate functions, the pull-up on the corresponding pins are disabled. The port pins are
tri-stated when a reset condition becomes active, even if the clock is not running.
All Port B pins are connected to a low-level detector that can trigger the low-level input
interrupt. See “Low-level Input Interrupt” on page 21 for details. In addition, Port B has
the following alternate functions:
• INT1 – Port B, Bit 4
INT1, External Interrupt source 1. The PB4 pin can serve as an external interrupt source
to the MCU. See the interrupt description for details on how to enable and configure this
interrupt. If the interrupt is enabled, the pull-up resistor on PB4 is disabled and PB4 will
not give low-level interrupts.
• INT0 – Port B, Bit 3
INT0, External Interrupt source 0. The PB3 pin can serve as an external interrupt source
to the MCU. See the interrupt description for details on how to enable and configure this
interrupt. If the interrupt is enabled, the pull-up resistor on PB3 is disabled and PB3 will
not give low-level interrupts.
• T0 – Port B, Bit 2
T0, Timer/Counter0 Counter source. See the timer description for further details. If T0 is
used as the counter source, the pull-up resistor on PB2 is disabled and PB2 will not give
low-level interrupts.
Port Pin
PB0
PB1
PB2
PB3
PB4
Alternate Functions
AIN0 (Analog Comparator Positive Input)
AIN1 (Analog Comparator Negative Input)
T0 (Timer/Counter 0 External Counter Input)
INT0 (External Interrupt 0 Input)
INT1 (External Interrupt 1 Input)
ATtiny28L/V
IL
) if the inter-
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