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Diffstat (limited to 'peripherals/twi/twi.c')
| -rw-r--r-- | peripherals/twi/twi.c | 372 |
1 files changed, 372 insertions, 0 deletions
diff --git a/peripherals/twi/twi.c b/peripherals/twi/twi.c new file mode 100644 index 0000000..6437b73 --- /dev/null +++ b/peripherals/twi/twi.c @@ -0,0 +1,372 @@ +/* ----------------------------------------------------------------------------
+ * 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.
+ * ----------------------------------------------------------------------------
+ */
+
+//------------------------------------------------------------------------------
+/// \unit
+///
+/// !Purpose
+///
+/// Interface for configuration the Two Wire Interface (TWI) peripheral.
+///
+/// !Usage
+///
+/// -# Configures a TWI peripheral to operate in master mode, at the given
+/// frequency (in Hz) using TWI_Configure().
+/// -# Sends a STOP condition on the TWI using TWI_Stop().
+/// -# Starts a read operation on the TWI bus with the specified slave using
+/// TWI_StartRead(). Data must then be read using TWI_ReadByte() whenever
+/// a byte is available (poll using TWI_ByteReceived()).
+/// -# Starts a write operation on the TWI to access the selected slave using
+/// TWI_StartWrite(). A byte of data must be provided to start the write;
+/// other bytes are written next.
+/// -# Sends a byte of data to one of the TWI slaves on the bus using TWI_WriteByte().
+/// This function must be called once before TWI_StartWrite() with the first byte of data
+/// to send, then it shall be called repeatedly after that to send the remaining bytes.
+/// -# Check if a byte has been received and can be read on the given TWI
+/// peripheral using TWI_ByteReceived().
+/// Check if a byte has been sent using TWI_ByteSent().
+/// -# Check if the current transmission is complete (the STOP has been sent)
+/// using TWI_TransferComplete().
+/// -# Enables & disable the selected interrupts sources on a TWI peripheral
+/// using TWI_EnableIt() and TWI_DisableIt().
+/// -# Get current status register of the given TWI peripheral using
+/// TWI_GetStatus(). Get current status register of the given TWI peripheral, but
+/// masking interrupt sources which are not currently enabled using
+/// TWI_GetMaskedStatus().
+//------------------------------------------------------------------------------
+
+
+//------------------------------------------------------------------------------
+// Headers
+//------------------------------------------------------------------------------
+
+#include "twi.h"
+#include <utility/math.h>
+#include <utility/assert.h>
+#include <utility/trace.h>
+
+//------------------------------------------------------------------------------
+// Global functions
+//------------------------------------------------------------------------------
+
+//------------------------------------------------------------------------------
+/// Configures a TWI peripheral to operate in master mode, at the given
+/// frequency (in Hz). The duty cycle of the TWI clock is set to 50%.
+/// \param pTwi Pointer to an AT91S_TWI instance.
+/// \param twck Desired TWI clock frequency.
+/// \param mck Master clock frequency.
+//------------------------------------------------------------------------------
+void TWI_ConfigureMaster(AT91S_TWI *pTwi, unsigned int twck, unsigned int mck)
+{
+ unsigned int ckdiv = 0;
+ unsigned int cldiv;
+ unsigned char ok = 0;
+
+ TRACE_DEBUG("TWI_ConfigureMaster()\n\r");
+ SANITY_CHECK(pTwi);
+
+#ifdef AT91C_TWI_SVEN // TWI slave
+ // SVEN: TWI Slave Mode Enabled
+ pTwi->TWI_CR = AT91C_TWI_SVEN;
+#endif
+ // Reset the TWI
+ pTwi->TWI_CR = AT91C_TWI_SWRST;
+ pTwi->TWI_RHR;
+
+ // TWI Slave Mode Disabled, TWI Master Mode Disabled
+#ifdef AT91C_TWI_SVEN // TWI slave
+ pTwi->TWI_CR = AT91C_TWI_SVDIS;
+#endif
+ pTwi->TWI_CR = AT91C_TWI_MSDIS;
+
+ // Set master mode
+ pTwi->TWI_CR = AT91C_TWI_MSEN;
+
+ // Configure clock
+ while (!ok) {
+ cldiv = ((mck / (2 * twck)) - 3) / power(2, ckdiv);
+ if (cldiv <= 255) {
+
+ ok = 1;
+ }
+ else {
+
+ ckdiv++;
+ }
+ }
+
+ ASSERT(ckdiv < 8, "-F- Cannot find valid TWI clock parameters\n\r");
+ TRACE_DEBUG("Using CKDIV = %u and CLDIV/CHDIV = %u\n\r", ckdiv, cldiv);
+ pTwi->TWI_CWGR = 0;
+ pTwi->TWI_CWGR = (ckdiv << 16) | (cldiv << 8) | cldiv;
+}
+
+
+
+#ifdef AT91C_TWI_SVEN // TWI slave
+//------------------------------------------------------------------------------
+/// Configures a TWI peripheral to operate in slave mode
+/// \param pTwi Pointer to an AT91S_TWI instance.
+//------------------------------------------------------------------------------
+void TWI_ConfigureSlave(AT91S_TWI *pTwi, unsigned char slaveAddress)
+{
+ unsigned int i;
+
+ // TWI software reset
+ pTwi->TWI_CR = AT91C_TWI_SWRST;
+ pTwi->TWI_RHR;
+
+ // Wait at least 10 ms
+ for (i=0; i < 1000000; i++);
+
+ // TWI Slave Mode Disabled, TWI Master Mode Disabled
+ pTwi->TWI_CR = AT91C_TWI_SVDIS | AT91C_TWI_MSDIS;
+
+ // Slave Address
+ pTwi->TWI_SMR = 0;
+ pTwi->TWI_SMR = (slaveAddress << 16) & AT91C_TWI_SADR;
+
+ // SVEN: TWI Slave Mode Enabled
+ pTwi->TWI_CR = AT91C_TWI_SVEN;
+
+ // Wait at least 10 ms
+ for (i=0; i < 1000000; i++);
+ ASSERT( (pTwi->TWI_CR & AT91C_TWI_SVDIS)!=AT91C_TWI_SVDIS, "Problem slave mode");
+}
+#endif
+
+//------------------------------------------------------------------------------
+/// Sends a STOP condition on the TWI.
+/// \param pTwi Pointer to an AT91S_TWI instance.
+//------------------------------------------------------------------------------
+void TWI_Stop(AT91S_TWI *pTwi)
+{
+ SANITY_CHECK(pTwi);
+
+ pTwi->TWI_CR = AT91C_TWI_STOP;
+}
+
+//------------------------------------------------------------------------------
+/// Starts a read operation on the TWI bus with the specified slave, and returns
+/// immediately. Data must then be read using TWI_ReadByte() whenever a byte is
+/// available (poll using TWI_ByteReceived()).
+/// \param pTwi Pointer to an AT91S_TWI instance.
+/// \param address Slave address on the bus.
+/// \param iaddress Optional internal address bytes.
+/// \param isize Number of internal address bytes.
+//-----------------------------------------------------------------------------
+void TWI_StartRead(
+ AT91S_TWI *pTwi,
+ unsigned char address,
+ unsigned int iaddress,
+ unsigned char isize)
+{
+ //TRACE_DEBUG("TWI_StartRead()\n\r");
+ SANITY_CHECK(pTwi);
+ SANITY_CHECK((address & 0x80) == 0);
+ SANITY_CHECK((iaddress & 0xFF000000) == 0);
+ SANITY_CHECK(isize < 4);
+
+ // Set slave address and number of internal address bytes
+ pTwi->TWI_MMR = 0;
+ pTwi->TWI_MMR = (isize << 8) | AT91C_TWI_MREAD | (address << 16);
+
+ // Set internal address bytes
+ pTwi->TWI_IADR = 0;
+ pTwi->TWI_IADR = iaddress;
+
+ // Send START condition
+ pTwi->TWI_CR = AT91C_TWI_START;
+}
+
+//-----------------------------------------------------------------------------
+/// Reads a byte from the TWI bus. The read operation must have been started
+/// using TWI_StartRead() and a byte must be available (check with
+/// TWI_ByteReceived()).
+/// Returns the byte read.
+/// \param pTwi Pointer to an AT91S_TWI instance.
+//-----------------------------------------------------------------------------
+unsigned char TWI_ReadByte(AT91S_TWI *pTwi)
+{
+ SANITY_CHECK(pTwi);
+
+ return pTwi->TWI_RHR;
+}
+
+//-----------------------------------------------------------------------------
+/// Sends a byte of data to one of the TWI slaves on the bus. This function
+/// must be called once before TWI_StartWrite() with the first byte of data
+/// to send, then it shall be called repeatedly after that to send the
+/// remaining bytes.
+/// \param pTwi Pointer to an AT91S_TWI instance.
+/// \param byte Byte to send.
+//-----------------------------------------------------------------------------
+void TWI_WriteByte(AT91S_TWI *pTwi, unsigned char byte)
+{
+ SANITY_CHECK(pTwi);
+
+ pTwi->TWI_THR = byte;
+}
+
+//-----------------------------------------------------------------------------
+/// Starts a write operation on the TWI to access the selected slave, then
+/// returns immediately. A byte of data must be provided to start the write;
+/// other bytes are written next.
+/// \param pTwi Pointer to an AT91S_TWI instance.
+/// \param address Address of slave to acccess on the bus.
+/// \param iaddress Optional slave internal address.
+/// \param isize Number of internal address bytes.
+/// \param byte First byte to send.
+//-----------------------------------------------------------------------------
+void TWI_StartWrite(
+ AT91S_TWI *pTwi,
+ unsigned char address,
+ unsigned int iaddress,
+ unsigned char isize,
+ unsigned char byte)
+{
+ //TRACE_DEBUG("TWI_StartWrite()\n\r");
+ SANITY_CHECK(pTwi);
+ SANITY_CHECK((address & 0x80) == 0);
+ SANITY_CHECK((iaddress & 0xFF000000) == 0);
+ SANITY_CHECK(isize < 4);
+
+ // Set slave address and number of internal address bytes
+ pTwi->TWI_MMR = 0;
+ pTwi->TWI_MMR = (isize << 8) | (address << 16);
+
+ // Set internal address bytes
+ pTwi->TWI_IADR = 0;
+ pTwi->TWI_IADR = iaddress;
+
+ // Write first byte to send
+ TWI_WriteByte(pTwi, byte);
+}
+
+//-----------------------------------------------------------------------------
+/// Returns 1 if a byte has been received and can be read on the given TWI
+/// peripheral; otherwise, returns 0. This function resets the status register
+/// of the TWI.
+/// \param pTwi Pointer to an AT91S_TWI instance.
+//-----------------------------------------------------------------------------
+unsigned char TWI_ByteReceived(AT91S_TWI *pTwi)
+{
+ return ((pTwi->TWI_SR & AT91C_TWI_RXRDY) == AT91C_TWI_RXRDY);
+}
+
+//-----------------------------------------------------------------------------
+/// Returns 1 if a byte has been sent, so another one can be stored for
+/// transmission; otherwise returns 0. This function clears the status register
+/// of the TWI.
+/// \param pTwi Pointer to an AT91S_TWI instance.
+//-----------------------------------------------------------------------------
+unsigned char TWI_ByteSent(AT91S_TWI *pTwi)
+{
+ return ((pTwi->TWI_SR & AT91C_TWI_TXRDY) == AT91C_TWI_TXRDY);
+}
+
+//-----------------------------------------------------------------------------
+/// Returns 1 if the current transmission is complete (the STOP has been sent);
+/// otherwise returns 0.
+/// \param pTwi Pointer to an AT91S_TWI instance.
+//-----------------------------------------------------------------------------
+unsigned char TWI_TransferComplete(AT91S_TWI *pTwi)
+{
+ return ((pTwi->TWI_SR & AT91C_TWI_TXCOMP) == AT91C_TWI_TXCOMP);
+}
+
+//-----------------------------------------------------------------------------
+/// Enables the selected interrupts sources on a TWI peripheral.
+/// \param pTwi Pointer to an AT91S_TWI instance.
+/// \param sources Bitwise OR of selected interrupt sources.
+//-----------------------------------------------------------------------------
+void TWI_EnableIt(AT91S_TWI *pTwi, unsigned int sources)
+{
+ SANITY_CHECK(pTwi);
+ SANITY_CHECK((sources & 0xFFFFF088) == 0);
+
+ pTwi->TWI_IER = sources;
+}
+
+//-----------------------------------------------------------------------------
+/// Disables the selected interrupts sources on a TWI peripheral.
+/// \param pTwi Pointer to an AT91S_TWI instance.
+/// \param sources Bitwise OR of selected interrupt sources.
+//-----------------------------------------------------------------------------
+void TWI_DisableIt(AT91S_TWI *pTwi, unsigned int sources)
+{
+ SANITY_CHECK(pTwi);
+ SANITY_CHECK((sources & 0xFFFFF088) == 0);
+
+ pTwi->TWI_IDR = sources;
+}
+
+//-----------------------------------------------------------------------------
+/// Returns the current status register of the given TWI peripheral. This
+/// resets the internal value of the status register, so further read may yield
+/// different values.
+/// \param pTwi Pointer to an AT91S_TWI instance.
+//-----------------------------------------------------------------------------
+unsigned int TWI_GetStatus(AT91S_TWI *pTwi)
+{
+ SANITY_CHECK(pTwi);
+
+ return pTwi->TWI_SR;
+}
+
+//-----------------------------------------------------------------------------
+/// Returns the current status register of the given TWI peripheral, but
+/// masking interrupt sources which are not currently enabled.
+/// This resets the internal value of the status register, so further read may
+/// yield different values.
+/// \param pTwi Pointer to an AT91S_TWI instance.
+//-----------------------------------------------------------------------------
+unsigned int TWI_GetMaskedStatus(AT91S_TWI *pTwi)
+{
+ unsigned int status;
+
+ SANITY_CHECK(pTwi);
+
+ status = pTwi->TWI_SR;
+ status &= pTwi->TWI_IMR;
+
+ return status;
+}
+//-----------------------------------------------------------------------------
+/// Sends a STOP condition. STOP Condition is sent just after completing
+/// the current byte transmission in master read mode.
+/// \param pTwi Pointer to an AT91S_TWI instance.
+//-----------------------------------------------------------------------------
+void TWI_SendSTOPCondition(AT91S_TWI *pTwi)
+{
+ SANITY_CHECK(pTwi);
+
+ pTwi->TWI_CR |= AT91C_TWI_STOP;
+}
+
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