ATMEGA325-16AJ ATMEL [ATMEL Corporation], ATMEGA325-16AJ Datasheet - Page 150

• Manufacturer Part Number: ATMEGA325-16AJ
• Description: 8-bit Microcontroller with In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

Data Modes
150
ATmega325/3250/645/6450
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 Figure 67 and Figure 68. Data bits are shifted out and latched in on oppo-
site edges of the SCK signal, ensuring sufficient time for data signals to stabilize. This is
clearly seen by summarizing Table 65 and Table 66, as done below:
Table 68. CPOL Functionality
Figure 67. SPI Transfer Format with CPHA = 0
Figure 68. SPI Transfer Format with CPHA = 1
CPOL=0, CPHA=0
CPOL=0, CPHA=1
CPOL=1, CPHA=0
CPOL=1, CPHA=1
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
MSB first (DORD = 0)
LSB first (DORD = 1)
MSB first (DORD = 0)
LSB first (DORD = 1)
MSB
LSB
MSB
LSB
Sample (Falling)
Sample (Rising)
Bit 6
Bit 1
Leading Edge
Setup (Falling)
Setup (Rising)
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)
Trailing eDge
Setup (Rising)
Bit 3
Bit 4
Bit 2
Bit 5
Bit 2
Bit 5
Bit 1
Bit 6
Bit 1
Bit 6
2570A–AVR–09/04
LSB
MSB
SPI Mode
LSB
MSB
0
1
2
3