ATmega644P Atmel Corporation, ATmega644P Datasheet - Page 244
![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
8011O–AVR–07/10
in ADCSRA. The prescaler keeps running for as long as the ADEN bit is set, and is continuously
reset when ADEN is low.
When initiating a single ended conversion by setting the ADSC bit in ADCSRA, the conversion
starts at the following rising edge of the ADC clock cycle. See
page 246
A normal conversion takes 13 ADC clock cycles. The first conversion after the ADC is switched
on (ADEN in ADCSRA is set) takes 25 ADC clock cycles in order to initialize the analog circuitry.
When the bandgap reference voltage is used as input to the ADC, it will take a certain time for
the voltage to stabilize. If not stabilized, the first value read after the first conversion may be
wrong.
The actual sample-and-hold takes place 1.5 ADC clock cycles after the start of a normal conver-
sion and 13.5 ADC clock cycles after the start of a first conversion. When a conversion is
complete, the result is written to the ADC Data Registers, and ADIF is set. In single conversion
mode, ADSC is cleared simultaneously. The software may then set ADSC again, and a new
conversion will be initiated on the first rising ADC clock edge.
When Auto Triggering is used, the prescaler is reset when the trigger event occurs. This assures
a fixed delay from the trigger event to the start of conversion. In this mode, the sample-and-hold
takes place 2 ADC clock cycles after the rising edge on the trigger source signal. Three addi-
tional CPU clock cycles are used for synchronization logic.
When using Differential mode, along with Auto Trigging from a source other than the ADC Con-
version Complete, each conversion will require 25 ADC clocks. This is because the ADC must
be disabled and re-enabled after every conversion.
In Free Running mode, a new conversion will be started immediately after the conversion com-
pletes, while ADSC remains high. For a summary of conversion times, see
246.
Figure 20-4. ADC Timing Diagram, First Conversion (Single Conversion Mode)
Cycle Number
ADC Clock
ADEN
ADSC
ADIF
ADCH
ADCL
for details on differential conversion timing.
1
2
MUX and REFS
Update
12
13
14
15
Sample & Hold
16
First Conversion
17
ATmega164P/324P/644P
18
19
20
21
”Differential Gain Channels” on
22
Conversion
Complete
23
24
25
Table 20-1 on page
MSB of Result
LSB of Result
Next
Conversion
1
MUX and REFS
Update
2
3
244