Rainbow Electronics ATmega162V - Manual (Page 5)

5
ATmega162/V
2513E–AVR–09/03
ATmega161 Compatibility
Mode Programming the M161C will change the following functionality:
• The extended I/O map will be configured as internal RAM once the M161C Fuse is
programmed.
• The timed sequence for changing the Watchdog Time-out period is disabled. See
“Timed Sequences for Changing the Configuration of the Watchdog Timer” on page
55 for details.
• The double buffering of the USART Receive Registers is disabled. See “AVR
USART vs. AVR UART – Compatibility” on page 167 for details.
• Pin change interrupts are not supported (Control Registers are located in Extended
I/O).
• One 16 bits Timer/Counter (Timer/Counter1) only. Timer/Counter3 is not accessible.
Note that the shared UBRRHI Register in ATmega161 is split into two separate registers
in ATmega162, UBRR0H and UBRR1H. The location of these registers will not be
affected by the ATmega161 compatibility fuse.
Pin Descriptions
VCC Digital supply voltage
GND Ground
Port A (PA7..PA0) Port A is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each
bit). The Port A output buffers have symmetrical drive characteristics with both high sink
and source capability. When pins PA0 to PA7 are used as inputs and are externally
pulled low, they will source current if the internal 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 ATmega162 as listed
on page 71.
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 ATmega162 as listed
on page 71.
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. If the JTAG interface is
enabled, the pull-up resistors on pins PC7(TDI), PC5(TMS) and PC4(TCK) will be acti-
vated even if a Reset occurs.
Port C also serves the functions of the JTAG interface and other special features of the
ATmega162 as listed on page 74.