Chapter 12 Serial Peripheral Interface (S08SPIV4)
MC9S08LG32 MCU Series, Rev. 5
294
Freescale Semiconductor
The SS output is available only in master mode during normal SPI operation by asserting the SSOE and
MODFEN bits as shown in
The mode fault feature is disabled while SS output is enabled.
NOTE
Care must be taken when using the SS output feature in a multi-master
system since the mode fault feature is not available for detecting system
errors between masters.
14.5.4.2
Bidirectional Mode (MOMI or SISO)
The bidirectional mode is selected when the SPC0 bit is set in SPI Control Register 2 (see
). In
this mode, the SPI uses only one serial data pin for the interface with external device(s). The MSTR bit
decides which pin to use. The MOSI pin becomes the serial data I/O (MOMI) pin for the master mode, and
the MISO pin becomes serial data I/O (SISO) pin for the slave mode. The MISO pin in master mode and
MOSI pin in slave mode are not used by the SPI.
Table 14-9. Normal Mode and Bidirectional Mode
The direction of each serial I/O pin depends on the BIDIROE bit. If the pin is configured as an output,
serial data from the shift register is driven out on the pin. The same pin is also the serial input to the shift
register.
The SPSCK is output for the master mode and input for the slave mode.
The SS is the input or output for the master mode, and it is always the input for the slave mode.
The bidirectional mode does not affect SPSCK and SS functions.
When SPE = 1
Master Mode MSTR = 1
Slave Mode MSTR = 0
Normal Mode
SPC0 = 0
Bidirectional Mode
SPC0 = 1
Serial Out
Serial In
SPI
MOSI
MISO
Serial Out
Serial In
SPI
MOSI
MISO
Serial Out
Serial In
SPI
MOMI
BIDIROE
Serial Out
Serial In
SPI
BIDIROE
SOSI
Содержание MC9S08LG16
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Страница 26: ...Chapter 1 Device Overview MC9S08LG32 MCU Series Rev 5 26 Freescale Semiconductor...
Страница 40: ...Chapter 2 Pins and Connections MC9S08LG32 MCU Series Rev 5 40 Freescale Semiconductor...
Страница 96: ...Chapter 5 Resets Interrupts and General System Control MC9S08LG32 MCU Series Rev 5 96 Freescale Semiconductor...
Страница 296: ...Chapter 12 Serial Peripheral Interface S08SPIV4 MC9S08LG32 MCU Series Rev 5 296 Freescale Semiconductor...
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