ATMEGA325A-MU Atmel, ATMEGA325A-MU Datasheet - Page 165

• Manufacturer Part Number: ATMEGA325A-MU
• Description: IC MCU AVR 32K FLASH 64VQFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA325A-MU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: SPI, UART/USART, USI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 54
• Program Memory Size: 32KB (16K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 1K x 8
• Ram Size: 2K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-VFQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

18.4
8285B–AVR–03/11
Data Modes
ATmega165A/165PA/325A/325PA/3250A/3250PA/6
There are four combinations of SCK phase and polarity with respect to serial data, which are
determined by control bits CPHA and CPOL. The SPI data transfer formats are shown in
18-3
nal, ensuring sufficient time for data signals to stabilize. This is clearly seen by summarizing
Table 18-3
Table 18-2.
Figure 18-3. SPI Transfer Format with CPHA = 0
Figure 18-4. SPI Transfer Format with CPHA = 1
and
CPOL=0, CPHA=0
CPOL=0, CPHA=1
CPOL=1, CPHA=0
CPOL=1, CPHA=1
Figure
SCK (CPOL = 0)
mode 0
SCK (CPOL = 1)
mode 2
SAMPLE I
MOSI/MISO
CHANGE 0
MOSI PIN
CHANGE 0
MISO PIN
SCK (CPOL = 0)
mode 1
SCK (CPOL = 1)
mode 3
SAMPLE I
MOSI/MISO
CHANGE 0
MOSI PIN
CHANGE 0
MISO PIN
SS
SS
and
MSB first (DORD = 0)
LSB first (DORD = 1)
MSB first (DORD = 0)
LSB first (DORD = 1)
CPOL Functionality
Table
18-4. Data bits are shifted out and latched in on opposite edges of the SCK sig-
18-4, as done below:
MSB
LSB
MSB
LSB
Sample (Falling)
Sample (Rising)
Leading Edge
Setup (Falling)
Setup (Rising)
Bit 6
Bit 1
Bit 6
Bit 1
Bit 5
Bit 2
Bit 5
Bit 2
Bit 4
Bit 3
Bit 4
Bit 3
Bit 3
Bit 4
Sample (Falling)
Sample (Rising)
Setup (Falling)
Setup (Rising)
Trailing eDge
Bit 3
Bit 4
Bit 2
Bit 5
Bit 2
Bit 5
Bit 1
Bit 6
Bit 1
Bit 6
LSB
MSB
LSB
MSB
SPI Mode
0
1
2
3
Figure
165