diff options
Diffstat (limited to 'peripherals/spi/spi.c')
| -rw-r--r-- | peripherals/spi/spi.c | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/peripherals/spi/spi.c b/peripherals/spi/spi.c new file mode 100644 index 0000000..16eba71 --- /dev/null +++ b/peripherals/spi/spi.c @@ -0,0 +1,194 @@ +/* ----------------------------------------------------------------------------
+ * ATMEL Microcontroller Software Support
+ * ----------------------------------------------------------------------------
+ * Copyright (c) 2008, Atmel Corporation
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the disclaimer below.
+ *
+ * Atmel's name may not be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * DISCLAIMER: THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE
+ * DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
+ * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
+ * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * ----------------------------------------------------------------------------
+ */
+
+//------------------------------------------------------------------------------
+// Headers
+//------------------------------------------------------------------------------
+
+#include "spi.h"
+
+//------------------------------------------------------------------------------
+// Exported functions
+//------------------------------------------------------------------------------
+//------------------------------------------------------------------------------
+/// Enables a SPI peripheral
+/// \param spi Pointer to an AT91S_SPI instance.
+//------------------------------------------------------------------------------
+void SPI_Enable(AT91S_SPI *spi)
+{
+ spi->SPI_CR = AT91C_SPI_SPIEN;
+}
+
+//------------------------------------------------------------------------------
+/// Disables a SPI peripheral.
+/// \param spi Pointer to an AT91S_SPI instance.
+//------------------------------------------------------------------------------
+void SPI_Disable(AT91S_SPI *spi)
+{
+ spi->SPI_CR = AT91C_SPI_SPIDIS;
+}
+
+//------------------------------------------------------------------------------
+/// Configures a SPI peripheral as specified. The configuration can be computed
+/// using several macros (see "SPI configuration macros") and the constants
+/// defined in LibV3 (AT91C_SPI_*).
+/// \param spi Pointer to an AT91S_SPI instance.
+/// \param id Peripheral ID of the SPI.
+/// \param configuration Value of the SPI configuration register.
+//------------------------------------------------------------------------------
+void SPI_Configure(AT91S_SPI *spi,
+ unsigned int id,
+ unsigned int configuration)
+{
+ AT91C_BASE_PMC->PMC_PCER = 1 << id;
+ spi->SPI_CR = AT91C_SPI_SPIDIS;
+ // Execute a software reset of the SPI twice
+ spi->SPI_CR = AT91C_SPI_SWRST;
+ spi->SPI_CR = AT91C_SPI_SWRST;
+ spi->SPI_MR = configuration;
+}
+
+//------------------------------------------------------------------------------
+/// Configures a chip select of a SPI peripheral. The chip select configuration
+/// is computed using the definition provided by the LibV3 (AT91C_SPI_*).
+/// \param spi Pointer to an AT91S_SPI instance.
+/// \param npcs Chip select to configure (1, 2, 3 or 4).
+/// \param configuration Desired chip select configuration.
+//------------------------------------------------------------------------------
+void SPI_ConfigureNPCS(AT91S_SPI *spi,
+ unsigned int npcs,
+ unsigned int configuration)
+{
+ spi->SPI_CSR[npcs] = configuration;
+}
+
+//------------------------------------------------------------------------------
+/// Sends data through a SPI peripheral. If the SPI is configured to use a fixed
+/// peripheral select, the npcs value is meaningless. Otherwise, it identifies
+/// the component which shall be addressed.
+/// \param spi Pointer to an AT91S_SPI instance.
+/// \param npcs Chip select of the component to address (1, 2, 3 or 4).
+/// \param data Word of data to send.
+//------------------------------------------------------------------------------
+void SPI_Write(AT91S_SPI *spi, unsigned int npcs, unsigned short data)
+{
+ // Discard contents of RDR register
+ //volatile unsigned int discard = spi->SPI_RDR;
+
+ // Send data
+ while ((spi->SPI_SR & AT91C_SPI_TXEMPTY) == 0);
+ spi->SPI_TDR = data | SPI_PCS(npcs);
+ while ((spi->SPI_SR & AT91C_SPI_TDRE) == 0);
+}
+
+//------------------------------------------------------------------------------
+/// Sends the contents of buffer through a SPI peripheral, using the PDC to
+/// take care of the transfer.
+/// \param spi Pointer to an AT91S_SPI instance.
+/// \param buffer Data buffer to send.
+/// \param length Length of the data buffer.
+//------------------------------------------------------------------------------
+unsigned char SPI_WriteBuffer(AT91S_SPI *spi,
+ void *buffer,
+ unsigned int length)
+{
+#if !defined(CHIP_SPI_DMA)
+ // Check if first bank is free
+ if (spi->SPI_TCR == 0) {
+
+ spi->SPI_TPR = (unsigned int) buffer;
+ spi->SPI_TCR = length;
+ spi->SPI_PTCR = AT91C_PDC_TXTEN;
+ return 1;
+ }
+ // Check if second bank is free
+ else if (spi->SPI_TNCR == 0) {
+
+ spi->SPI_TNPR = (unsigned int) buffer;
+ spi->SPI_TNCR = length;
+ return 1;
+ }
+#endif
+ // No free banks
+ return 0;
+}
+
+//------------------------------------------------------------------------------
+/// Returns 1 if there is no pending write operation on the SPI; otherwise
+/// returns 0.
+/// \param pSpi Pointer to an AT91S_SPI instance.
+//------------------------------------------------------------------------------
+unsigned char SPI_IsFinished(AT91S_SPI *pSpi)
+{
+ return ((pSpi->SPI_SR & AT91C_SPI_TXEMPTY) != 0);
+}
+
+//------------------------------------------------------------------------------
+/// Reads and returns the last word of data received by a SPI peripheral. This
+/// method must be called after a successful SPI_Write call.
+/// \param spi Pointer to an AT91S_SPI instance.
+//------------------------------------------------------------------------------
+unsigned short SPI_Read(AT91S_SPI *spi)
+{
+ while ((spi->SPI_SR & AT91C_SPI_RDRF) == 0);
+ return spi->SPI_RDR & 0xFFFF;
+}
+
+//------------------------------------------------------------------------------
+/// Reads data from a SPI peripheral until the provided buffer is filled. This
+/// method does NOT need to be called after SPI_Write or SPI_WriteBuffer.
+/// \param spi Pointer to an AT91S_SPI instance.
+/// \param buffer Data buffer to store incoming bytes.
+/// \param length Length in bytes of the data buffer.
+//------------------------------------------------------------------------------
+unsigned char SPI_ReadBuffer(AT91S_SPI *spi,
+ void *buffer,
+ unsigned int length)
+{
+#if !defined(CHIP_SPI_DMA)
+ // Check if the first bank is free
+ if (spi->SPI_RCR == 0) {
+
+ spi->SPI_RPR = (unsigned int) buffer;
+ spi->SPI_RCR = length;
+ spi->SPI_PTCR = AT91C_PDC_RXTEN;
+ return 1;
+ }
+ // Check if second bank is free
+ else if (spi->SPI_RNCR == 0) {
+
+ spi->SPI_RNPR = (unsigned int) buffer;
+ spi->SPI_RNCR = length;
+ return 1;
+ }
+#endif
+ // No free bank
+ return 0;
+}
+
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