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STM32: SPI 3 wires mode not supported in SPI slave #5565

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Merged
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Nov 30, 2017
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STM32: SPI 3 wires mode not supported in SPI slave #5565

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11 changes: 11 additions & 0 deletions targets/TARGET_STM/stm_spi_api.c
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,7 @@
*/
#include "mbed_assert.h"
#include "mbed_error.h"
#include "mbed_debug.h"
#include "spi_api.h"

#if DEVICE_SPI
Expand Down Expand Up @@ -286,6 +287,16 @@ void spi_format(spi_t *obj, int bits, int mode, int slave)

handle->Init.Mode = (slave) ? SPI_MODE_SLAVE : SPI_MODE_MASTER;

if (slave && (handle->Init.Direction == SPI_DIRECTION_1LINE)) {
/* SPI slave implemtation in MBED does not support the 3 wires SPI.
* (e.g. when MISO is not connected). So we're forcing slave in
* 2LINES mode. As MISO is not connected, slave will only read
* from master, and cannot write to it. Inform user.
*/
debug("3 wires SPI slave not supported - slave will only read\r\n");
handle->Init.Direction = SPI_DIRECTION_2LINES;
}

init_spi(obj);
}

Expand Down