9
4317KS–AVR–03/2013
AT90PWM2/3/2B/3B
The Idle mode stops the CPU while allowing the SRAM, Timer/Counters, SPI ports and interrupt
system to continue functioning. The Power-down mode saves the register contents but freezes
the Oscillator, disabling all other chip functions until the next interrupt or Hardware Reset. The
ADC Noise Reduction mode stops the CPU and all I/O modules except ADC, to minimize switch-
ing noise during ADC conversions. In Standby mode, the Crystal/Resonator Oscillator is running
while the rest of the device is sleeping. This allows very fast start-up combined with low power
consumption.
The device is manufactured using Atmel’s high-density nonvolatile memory technology. The On-
chip ISP Flash allows the program memory to be reprogrammed in-system through an SPI serial
interface, by a conventional nonvolatile memory programmer, or by an On-chip Boot program
running on the AVR core. The boot program can use any interface to download the application
program in the application Flash memory. Software in the Boot Flash section will continue to run
while the Application Flash section is updated, providing true Read-While-Write operation. By
combining an 8-bit RISC CPU with In-System Self-Programmable Flash on a monolithic chip,
the Atmel AT90PWM2/3 is a powerful microcontroller that provides a highly flexible and cost
effective solution to many embedded control applications.
The AT90PWM2/3 AVR is supported with a full suite of program and system development tools
including: C compilers, macro assemblers, program debugger/simulators, in-circuit emulators,
and evaluation kits.
4.2 Pin Descriptions
4.2.1 VCC
Digital supply voltage.
4.2.2 GND
Ground.
4.2.3 Port B (PB7..PB0)
Port B is an 8-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 AT90PWM2/2B/3/3B as listed
on page 69.
4.2.4 Port C (PC7..PC0)
Port C is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The
Port C output buffers have symmetrical drive characteristics with both high sink and source
capability. As inputs, Port C pins that are externally pulled low will source current if the pull-up
resistors are activated. The Port C pins are tri-stated when a reset condition becomes active,
even if the clock is not running.
Port C is not available on 24 pins package.
Port C also serves the functions of special features of the AT90PWM2/2B/3/3B as listed on page
72.
