Chapter 17 Serial Peripheral Interface
17-5
17.3.4 Transfer
Format
During a SPI transfer, data is simultaneously transmitted (shifted out serially) and received serially
(shifted in serially). The serial clock synchronizes shifting and sampling of the information on the two
serial data lines.
The transfer format depends on the setting of the SPHA and SPOL bits in the SPI Control Register 0
(SPCR0). SPHA switches between two fundamentally different protocols, which are described below.
17.3.4.1 SPHA Equals 0 Format
Figure 17.3.1 shows the transfer format for a SPHA=0 transfer.
Figure 17.3.1 Transfer format when SPHA is “0”.
In this transfer format, the bit value is captured on the first clock edge. This will be on a rising
edge when SPOL bit equals zero and on a falling edge when SPOL equals one. The value on the
SPIIN and SPIOUT signals changes with the second clock edge on SPICLK. This clock edge will
be a falling edge when SPOL equals zero and a rising edge, when SPOL equals one. With SPOL
equal to zero, the shift clock will be idle low. With SPOL equals 1 it will idle high.
SPICLK
(SPOL=0)
SPICLK
(SPOL=1)
SPIOUT
MSB B6 B5 B4 B3 B2 B1
LSB
MSB B6 B5 B4 B3 B2 B1
LSB
Sample Point
1
2
3
4
5
6
7
8
SPIIN
Summary of Contents for TMPR4925
Page 1: ...64 Bit TX System RISC TX49 Family TMPR4925 Rev 3 0 ...
Page 4: ......
Page 15: ...Handling Precautions ...
Page 16: ......
Page 18: ...1 Using Toshiba Semiconductors Safely 1 2 ...
Page 40: ...3 General Safety Precautions and Usage Considerations 3 18 ...
Page 42: ...4 Precautions and Usage Considerations 4 2 ...
Page 43: ...TMPR4925 ...
Page 44: ......
Page 54: ...Chapter 1 Features 1 8 ...
Page 58: ...Chapter 2 Block Diagram 2 4 ...
Page 88: ...Chapter 4 Address Mapping 4 12 ...
Page 226: ...Chapter 8 DMA Controller 8 58 ...
Page 260: ...Chapter 9 SDRAM Controller 9 34 ...
Page 480: ...Chapter 15 Interrupt Controller 15 32 ...
Page 554: ...Chapter 19 Real Time Clock RTC 19 8 ...
Page 555: ...Chapter 20 Removed 20 1 20 Removed ...
Page 556: ...Chapter 20 Removed 20 2 ...
Page 564: ...Chapter 21 Extended EJTAG Interface 21 8 ...
Page 580: ...Chapter 22 Electrical Characteristics 22 16 ...
Page 588: ...Chapter 24 Usage Notes 24 2 ...