Pin Descriptions; About Code Examples; Avr Cpu Core; Introduction - Atmel ATtiny25 Manual

2.3

Pin Descriptions

2.3.1 VCC
2.3.2 GND
2.3.3 Port B (PB5..PB0)
2.3.4 RESET

3. About Code Examples

4. AVR CPU Core

4.1

Introduction

7598H–AVR–07/09
Supply voltage.
Ground.
Port B is a 6-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The
Port B output buffers have symmetrical drive characteristics with both high sink and source
capability. As inputs, Port B pins that are externally pulled low will source current if the pull-up
resistors are activated. The Port B pins are tri-stated when a reset condition becomes active,
even if the clock is not running.
Port B also serves the functions of various special features of the ATtiny25/45/85 as listed on
page 54.
Reset input. A low level on this pin for longer than the minimum pulse length will generate a
reset, even if the clock is not running. The minimum pulse length is given in
37. Shorter pulses are not guaranteed to generate a reset.
This documentation contains simple code examples that briefly show how to use various parts of
the device. These code examples assume that the part specific header file is included before
compilation. Be aware that not all C compiler vendors include bit definitions in the header files
and interrupt handling in C is compiler dependent. Please confirm with the C compiler documen-
tation for more details.
This section discusses the AVR core architecture in general. The main function of the CPU core
is to ensure correct program execution. The CPU must therefore be able to access memories,
perform calculations, control peripherals, and handle interrupts.
ATtiny25/45/85
Table 8-1 on page
5