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ATMEGA163 Datasheet(PDF) 5 Page - ATMEL Corporation |
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ATMEGA163 Datasheet(HTML) 5 Page - ATMEL Corporation |
5 / 187 page ![]() 5 ATmega163(L) 1142E–AVR–02/03 Port C also serves the functions of various special features of the ATmega163 as listed on page 124. Port D (PD7..PD0) Port D is an 8-bit bidirectional I/O port with internal pull-up resistors (selected for each bit). The Port D output buffers can sink 20 mA. As inputs, Port D pins that are externally pulled low will source current if the pull-up resistors are activated. Port D also serves the functions of various special features of the ATmega163 as listed on page 128. The Port D pins are tristated when a reset condition becomes active, even if the clock is not running. RESET Reset input. A low level on this pin for more than 500 ns will generate a Reset, even if the clock is not running. Shorter pulses are not guaranteed to generate a Reset. XTAL1 Input to the inverting Oscillator amplifier and input to the internal clock operating circuit. XTAL2 Output from the inverting Oscillator amplifier. AVCC This is the supply voltage pin for Port A and the A/D Converter. It should be externally connected to VCC, even if the ADC is not used. If the ADC is used, it should be con- nected to VCC through a low-pass filter. See page 105 for details on operation of the ADC. AREF AREF is the analog reference input pin for the A/D Converter. For ADC operations, a voltage in the range 2.5V to AVCC can be applied to this pin. AGND Analog ground. If the board has a separate analog ground plane, this pin should be con- nected to this ground plane. Otherwise, connect to GND. Clock Options The device has the following clock source options, selectable by Flash Fuse bits as shown: Note: 1. “1” means unprogrammed, “0” means programmed. The various choices for each clocking option give different start-up times as shown in Table 5 on page 25. Internal RC Oscillator The internal RC Oscillator option is an On-chip Oscillator running at a fixed frequency of nominally 1 MHz. If selected, the device can operate with no external components. The device is shipped with this option selected. See “EEPROM Read/Write Access” on page 62 for information on calibrating this Oscillator. Table 1. Device Clocking Options Select(1) Device Clocking Option CKSEL3..0 External Crystal/Ceramic Resonator 1111 - 1010 External Low-frequency Crystal 1001 - 1000 External RC Oscillator 0111 - 0101 Internal RC Oscillator 0100 - 0010 External Clock 0001 - 0000 |