K Wilson
2014-06-13 22:59:32 UTC
Here is how the stm32 knows when to drive the bidirectional MOSI line:
The STM32f4 reference manual: (p801)
1 clock and 1 bidirectional data wire (BIDIMODE=1)
This mode is enabled by setting the BIDIMODE bit in the SPI_CR1 register. In this mode
SCK is used for the clock and MOSI in master or MISO in slave mode is used for data
communication. The transfer direction (Input/Output) is selected by the BIDIOE bit in the
SPI_CR1 register. When this bit is 1, the data line is output otherwise it is input.
The STM32f4 reference manual: (p801)
1 clock and 1 bidirectional data wire (BIDIMODE=1)
This mode is enabled by setting the BIDIMODE bit in the SPI_CR1 register. In this mode
SCK is used for the clock and MOSI in master or MISO in slave mode is used for data
communication. The transfer direction (Input/Output) is selected by the BIDIOE bit in the
SPI_CR1 register. When this bit is 1, the data line is output otherwise it is input.