ATmega644P Atmel Corporation, ATmega644P Datasheet - Page 74
![no-image](/images/manufacturer_photos/0/0/79/atmel_corporation_sml.jpg)
ATmega644P
Manufacturer Part Number
ATmega644P
Description
Manufacturer
Atmel Corporation
Specifications of ATmega644P
Flash (kbytes)
64 Kbytes
Pin Count
44
Max. Operating Frequency
20 MHz
Cpu
8-bit AVR
# Of Touch Channels
16
Hardware Qtouch Acquisition
No
Max I/o Pins
32
Ext Interrupts
32
Usb Speed
No
Usb Interface
No
Spi
3
Twi (i2c)
1
Uart
2
Graphic Lcd
No
Video Decoder
No
Camera Interface
No
Adc Channels
8
Adc Resolution (bits)
10
Adc Speed (ksps)
15
Analog Comparators
1
Resistive Touch Screen
No
Temp. Sensor
No
Crypto Engine
No
Sram (kbytes)
4
Eeprom (bytes)
2048
Self Program Memory
YES
Dram Memory
No
Nand Interface
No
Picopower
Yes
Temp. Range (deg C)
-40 to 85
I/o Supply Class
1.8 to 5.5
Operating Voltage (vcc)
1.8 to 5.5
Fpu
No
Mpu / Mmu
no / no
Timers
3
Output Compare Channels
6
Input Capture Channels
1
Pwm Channels
6
32khz Rtc
Yes
Calibrated Rc Oscillator
Yes
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Part Number:
ATMEGA644P
Manufacturer:
ATMEL/爱特梅尔
Quantity:
20 000
Part Number:
ATmega644P-20AU
Manufacturer:
ATMEL/爱特梅尔
Quantity:
20 000
Part Number:
ATmega644P-20MU
Manufacturer:
ATMEL/爱特梅尔
Quantity:
20 000
Company:
Part Number:
ATmega644P-20PU
Manufacturer:
Atmel
Quantity:
1 984
Company:
Part Number:
ATmega644P-A15MZ
Manufacturer:
ATMEL
Quantity:
3 500
Part Number:
ATmega644P-A15MZ
Manufacturer:
ATMEL/爱特梅尔
Quantity:
20 000
Company:
Part Number:
ATmega644PA-AU
Manufacturer:
PHILIPS
Quantity:
450
Part Number:
ATmega644PA-AU
Manufacturer:
MICROCHIP/微芯
Quantity:
20 000
Company:
Part Number:
ATmega644PA-AUR
Manufacturer:
ATMEL
Quantity:
1 400
11.2.2
11.2.3
11.2.4
8011O–AVR–07/10
Toggling the Pin
Switching Between Input and Output
Reading the Pin Value
If PORTxn is written logic one when the pin is configured as an output pin, the port pin is driven
high (one). If PORTxn is written logic zero when the pin is configured as an output pin, the port
pin is driven low (zero).
Writing a logic one to PINxn toggles the value of PORTxn, independent on the value of DDRxn.
Note that the SBI instruction can be used to toggle one single bit in a port.
When switching between tri-state ({DDxn, PORTxn} = 0b00) and output high ({DDxn, PORTxn}
= 0b11), an intermediate state with either pull-up enabled {DDxn, PORTxn} = 0b01) or output
low ({DDxn, PORTxn} = 0b10) must occur. Normally, the pull-up enabled state is fully accept-
able, as a high-impedant environment will not notice the difference between a strong high driver
and a pull-up. If this is not the case, the PUD bit in the MCUCR Register can be set to disable all
pull-ups in all ports.
Switching between input with pull-up and output low generates the same problem. The user
must use either the tri-state ({DDxn, PORTxn} = 0b00) or the output high state ({DDxn, PORTxn}
= 0b11) as an intermediate step.
Table 11-1
Table 11-1.
Independent of the setting of Data Direction bit DDxn, the port pin can be read through the
PINxn Register bit. As shown in
stitute a synchronizer. This is needed to avoid metastability if the physical pin changes value
near the edge of the internal clock, but it also introduces a delay.
gram of the synchronization when reading an externally applied pin value. The maximum and
minimum propagation delays are denoted t
DDxn
0
0
0
1
1
PORTxn
summarizes the control signals for the pin value.
0
1
1
0
1
Port Pin Configurations
(in MCUCR)
PUD
X
0
1
X
X
Figure
Output
Output
Input
Input
Input
11-2, the PINxn Register bit and the preceding latch con-
I/O
pd,max
Pull-up
and t
ATmega164P/324P/644P
Yes
No
No
No
No
pd,min
Comment
Tri-state (Hi-Z)
Pxn will source current if ext. pulled low.
Tri-state (Hi-Z)
Output Low (Sink)
Output High (Source)
respectively.
Figure 11-3
shows a timing dia-
74