ATMEGA644P-A15MZ Atmel, ATMEGA644P-A15MZ Datasheet - Page 200

• Manufacturer Part Number: ATMEGA644P-A15MZ
• Description: MCU AVR 64KB FLASH 16MHZ 44QFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA644P-A15MZ

• Package / Case: 44-VQFN Exposed Pad
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Speed: 16MHz
• Number Of I /o: 32
• Eeprom Size: 2K x 8
• Core Processor: AVR
• Program Memory Type: FLASH
• Ram Size: 4K x 8
• Program Memory Size: 64KB (64K x 8)
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Connectivity: I²C, SPI, UART/USART
• Core Size: 8-Bit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

18.4
18.5
200
SPI Data Modes and Timing
Frame Formats
ATmega164P/324P/644P
There are four combinations of XCKn (SCK) phase and polarity with respect to serial data, which
are determined by control bits UCPHAn and UCPOLn. The data transfer timing diagrams are
shown in
signal, ensuring sufficient time for data signals to stabilize. The UCPOLn and UCPHAn function-
ality is summarized in
all ongoing communication for both the Receiver and Transmitter.
Table 18-2.
Figure 18-1. UCPHAn and UCPOLn data transfer timing diagrams.
A serial frame for the MSPIM is defined to be one character of 8 data bits. The USART in MSPIM
mode has two valid frame formats:
• 8-bit data with MSB first
• 8-bit data with LSB first
A frame starts with the least or most significant data bit. Then the next data bits, up to a total of
eight, are succeeding, ending with the most or least significant bit accordingly. When a complete
frame is transmitted, a new frame can directly follow it, or the communication line can be set to
an idle (high) state.
UCPOLn
BAUD
f
UBRRn
OSC
XCK
Data setup (TXD)
Data sample (RXD)
Data setup (TXD)
Data sample (RXD)
0
0
1
1
XCK
Figure
UCPOLn and UCPHAn Functionality-
18-1. Data bits are shifted out and latched in on opposite edges of the XCKn
UCPHAn
Baud rate (in bits per second, bps)
System Oscillator clock frequency
Contents of the UBRRnH and UBRRnL Registers, (0-4095)
Table
0
1
0
1
UCPOL=0
18-2. Note that changing the setting of any of these bits will corrupt
SPI Mode
0
1
2
3
Leading Edge
Sample (Rising)
Setup (Rising)
Sample (Falling)
Setup (Falling)
Data setup (TXD)
Data sample (RXD)
Data setup (TXD)
Data sample (RXD)
XCK
XCK
UCPOL=1
Trailing Edge
Setup (Falling)
Sample (Falling)
Setup (Rising)
Sample (Rising)
7674F–AVR–09/09