Rainbow Electronics ATtiny15L - Manual (Page 4)

4
ATtiny15L
1187E–AVR–06/02
Pin Descriptions
VCC Supply voltage pin.
GND Ground pin.
Port B (PB5..PB0) Port B is a 6-bit I/O port. PB4..0 are I/O pins that can provide internal pull-ups (selected
for each bit). PB5 is input or open-drain output. The use of pin PB5 is defined by a fuse
and the special function associated with this pin is External Reset. The port pins are tri-
stated when a reset condition becomes active, even if the clock is not running.
Port B also accommodates analog I/O pins. The Port B pins with alternate functions are
shown in Table 1.
Analog Pins Up to four analog inputs can be selected as inputs to Analog-to-Digital Converter (ADC).
Internal Oscillators The internal Oscillator provides a clock rate of nominally 1.6 MHz for the system clock
(CK). Due to large initial variation (0.8 -1.6 MHz) of the internal Oscillator, a tuning capa-
bility is built in. Through an 8-bit control register – OSCCAL – the system clock rate can
be tuned with less than 1% steps of the nominal clock.
There is an internal PLL that provides a 16x clock rate locked to the system clock (CK)
for the use of the Peripheral Timer/Counter1. The nominal frequency of this peripheral
clock, PCK, is 25.6 MHz.
Table 1. Port B Alternate Functions
Port Pin Alternate Function
PB0 MOSI (Data Input Line for Memory Downloading)
AREF (ADC Voltage Reference)
AIN0 (Analog Comparator Positive Input)
PB1 MISO (Data Output Line for Memory Downloading)
OC1A (Timer/Counter PWM Output)
AIN1 (Analog Comparator Negative Input)
PB2 SCK (Serial Clock Input for Serial Programming)
INT0 (External Interrupt0 Input)
ADC1 (ADC Input Channel 1)
T0 (Timer/Counter0 External Counter Input)
PB3 ADC2 (ADC Input Channel 2)
PB4 ADC3 (ADC Input Channel 3)
PB5 RESET (External Reset Pin)
ADC0 (ADC Input Channel 0)