Rainbow-electronics ATmega8515L Manual de usuario descargar pdf (Pagina 130)

130

ATmega8515(L)

2512A–AVR–04/02

Data Modes Thereare fourcombinations ofSCKphaseandpolaritywithrespecttoserialdata,

which are determinedbycontrolbitsCPHAandCPOL.The SPIdata transferformats

are showninFigure 61andFigure 62. Data bits are shifted out andlatched in on oppo-

site edges of the SCK signal, ensuring sufficient time fordata signals to stabilize. This is

clearly seen by summarizing Table56 and Table57, asdone below:

Figure 61. SPI TransferFormat withCPHA = 0

Figure 62. SPI TransferFormat withCPHA = 1

Table 59. CPOL Functionality

Leading Edge Trailing Edge SPI Mode

CPOL=0,CPHA=0 Sample (Rising)Setup(Falling) 0

CPOL=0,CPHA=1 Setup(Rising)Sample (Falling) 1

CPOL=1,CPHA=0 Sample (Falling)Setup(Rising) 2

CPOL=1,CPHA=1 Setup(Falling)Sample (Rising)3

Bit 1

Bit 6

LSB

MSB

SCK (CPOL = 0)

mode 0

SAMPLE I

MOSI/MISO

CHANGE 0

MOSI PIN

CHANGE 0

MISO PIN

SCK (CPOL = 1)

mode 2

MSB

LSB

Bit 6

Bit 1

Bit 5

Bit 2

Bit 4

Bit 3

Bit 4

Bit 2

Bit 5

MSB first (DORD = 0)

LSB first (DORD = 1)

SCK (CPOL = 0)

mode 1

SAMPLE I

MOSI/MISO

CHANGE 0

MOSI PIN

CHANGE 0

MISO PIN

SCK (CPOL = 1)

mode 3

MSB

LSB

Bit 6

Bit 1

Bit 5

Bit 2

Bit 4

Bit 3

Bit 4

Bit 2

Bit 5

Bit 1

Bit 6

LSB

MSB

MSB first (DORD = 0)

LSB first (DORD = 1)

1 2 ... 125 126 127 128 129 130 131 132 133 134 135 ... 222 223

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