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ATMEGA644-20PU 用户编程技术手册 - Microchip(微芯)
制造商:
Microchip(微芯)
分类:
微控制器
封装:
DIP-40
描述:
8 位 megaAVR 微控制器,32KB 到 256KB 闪存我们在 RS Components 提供多款来自 Atmel 的 megaAVR 8 位微控制器。 每个微控制器均基于增强型 RISC 体系结构,并具有 QTouch 库支持。 所有微控制器类型具有不同 Kb 的系统内可编程内存、EEPROM 和 SRAM 以及不同引脚和封装类型。 **megaAVR 8 位微控制器类型** ATmega32 ATmega64 ATmega128 ATmega324 ATmega325 ATmega406 ATmega640 ATmega644 ATmega645 ATmega1280 ATmega1281 ATmega1284 ATmega2560 ATmega2561 ATmega3250 ATmega6450
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ATMEGA644-20PU数据手册
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5
2593OS–AVR–02/12
ATmega644
and source capability. As inputs, Port A pins that are externally pulled low will source current if
the pull-up resistors are activated. The Port A pins are tri-stated when a reset condition becomes
active, even if the clock is not running.
Port A also serves the functions of various special features of the ATmega644 as listed on page
73.
2.2.4 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 ATmega644 as listed on page
75.
2.2.5 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 also serves the functions of the JTAG interface, along with special features of the
ATmega644 as listed on page 78.
2.2.6 Port D (PD7:PD0)
Port D is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The
Port D output buffers have symmetrical drive characteristics with both high sink and source
capability. As inputs, Port D pins that are externally pulled low will source current if the pull-up
resistors are activated. The Port D pins are tri-stated when a reset condition becomes active,
even if the clock is not running.
Port D also serves the functions of various special features of the ATmega644 as listed on page
80.
2.2.7
RESET
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 ”System and Reset
Characteristics” on page 320. Shorter pulses are not guaranteed to generate a reset.
2.2.8 XTAL1
Input to the inverting Oscillator amplifier and input to the internal clock operating circuit.
2.2.9 XTAL2
Output from the inverting Oscillator amplifier.
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