ATmega406 Atmel Corporation, ATmega406 Datasheet - Page 60

• Manufacturer Part Number: ATmega406
• Manufacturer: Atmel Corporation

Specifications of ATmega406

• Flash (kbytes): 40 Kbytes
• Pin Count: 48
• Max. Operating Frequency: 1 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 8
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 18
• Ext Interrupts: 4
• Usb Speed: No
• Usb Interface: No
• Twi (i2c): 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 11
• Adc Resolution (bits): 12
• Adc Speed (ksps): 1.9
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: No
• Sram (kbytes): 2
• Eeprom (bytes): 512
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -30 to 85
• I/o Supply Class: 4.0 to 25
• Operating Voltage (vcc): 4.0 to 25
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 2
• Output Compare Channels: 3
• Pwm Channels: 2
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

13. Low Voltage I/O-Ports
13.1
60
Introduction
ATmega406
All low voltage AVR ports have true Read-Modify-Write functionality when used as general digi-
tal I/O ports. This means that the direction of one port pin can be changed without unintentionally
changing the direction of any other pin with the SBI and CBI instructions. The same applies
when changing drive value (if configured as output) or enabling/disabling of pull-up resistors (if
configured as input). All low voltage port pins have individually selectable pull-up resistors with a
supply-voltage invariant resistance. All I/O pins have protection diodes to both V
as indicated in
complete list of parameters.
Figure 13-1. Low Voltage I/O Pin Equivalent Schematic
All registers and bit references in this section are written in general form. A lower case “x” repre-
sents the numbering letter for the port, and a lower case “n” represents the bit number. However,
when using the register or bit defines in a program, the precise form must be used. For example,
PORTB3 for bit no. 3 in Port B, here documented generally as PORTxn. The physical I/O Regis-
ters and bit locations are listed in
Three I/O memory address locations are allocated for each low voltage port, one each for the
Data Register – PORTx, Data Direction Register – DDRx, and the Port Input Pins – PINx. The
Port Input Pins I/O location is read only, while the Data Register and the Data Direction Register
are read/write. However, writing a logic one to a bit in the PINx Register, will result in a toggle in
the corresponding bit in the Data Register. In addition, the Pull-up Disable – PUD bit in MCUCR
disables the pull-up function for all low voltage pins in all ports when set.
Using the I/O port as General Digital I/O is described in
I/O” on page
peripheral features on the device. How each alternate function interferes with the port pin is
described in
full description of the alternate functions.
Note that enabling the alternate function of some of the port pins does not affect the use of the
other pins in the port as general digital I/O.
”Alternate Port Functions” on page
61. Many low voltage port pins are multiplexed with alternate functions for the
Pxn
Figure 13-1 on page
”Register Description” on page
C
pin
60. Refer to
66. Refer to the individual module sections for a
”Electrical Characteristics” on page 225
”Low Voltage Ports as General Digital
"General Digital I/O" for
73.
See Figure
R
Details
pu
Logic
REG
2548E–AVR–07/06
and Ground
for a