diff options
Diffstat (limited to 'drivers/twi/twid.c')
| -rw-r--r-- | drivers/twi/twid.c | 344 |
1 files changed, 344 insertions, 0 deletions
diff --git a/drivers/twi/twid.c b/drivers/twi/twid.c new file mode 100644 index 0000000..d08d96a --- /dev/null +++ b/drivers/twi/twid.c @@ -0,0 +1,344 @@ +/* ----------------------------------------------------------------------------
+ * 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.
+ * ----------------------------------------------------------------------------
+ */
+
+
+#define TWITIMEOUTMAX 50000
+
+//------------------------------------------------------------------------------
+// Headers
+//------------------------------------------------------------------------------
+
+#include "twid.h"
+#include <twi/twi.h>
+#include <utility/assert.h>
+#include <utility/trace.h>
+
+//------------------------------------------------------------------------------
+// Local types
+//------------------------------------------------------------------------------
+
+/// TWI driver callback function.
+typedef void (*TwiCallback)(Async *);
+
+//------------------------------------------------------------------------------
+/// TWI asynchronous transfer descriptor.
+//------------------------------------------------------------------------------
+typedef struct _AsyncTwi {
+
+ /// Asynchronous transfer status.
+ volatile unsigned char status;
+ // Callback function to invoke when transfer completes or fails.
+ TwiCallback callback;
+ /// Pointer to the data buffer.
+ unsigned char *pData;
+ /// Total number of bytes to transfer.
+ unsigned int num;
+ /// Number of already transferred bytes.
+ unsigned int transferred;
+
+} AsyncTwi;
+
+//------------------------------------------------------------------------------
+// Global functions
+//------------------------------------------------------------------------------
+
+//------------------------------------------------------------------------------
+/// Initializes a TWI driver instance, using the given TWI peripheral. The
+/// peripheral must have been initialized properly before calling this function.
+/// \param pTwid Pointer to the Twid instance to initialize.
+/// \param pTwi Pointer to the TWI peripheral to use.
+//------------------------------------------------------------------------------
+void TWID_Initialize(Twid *pTwid, AT91S_TWI *pTwi)
+{
+ TRACE_DEBUG("TWID_Initialize()\n\r");
+ SANITY_CHECK(pTwid);
+ SANITY_CHECK(pTwi);
+
+ // Initialize driver
+ pTwid->pTwi = pTwi;
+ pTwid->pTransfer = 0;
+}
+
+//------------------------------------------------------------------------------
+/// Interrupt handler for a TWI peripheral. Manages asynchronous transfer
+/// occuring on the bus. This function MUST be called by the interrupt service
+/// routine of the TWI peripheral if asynchronous read/write are needed.
+/// \param pTwid Pointer to a Twid instance.
+//------------------------------------------------------------------------------
+void TWID_Handler(Twid *pTwid)
+{
+ unsigned char status;
+ AsyncTwi *pTransfer = (AsyncTwi *) pTwid->pTransfer;
+ AT91S_TWI *pTwi = pTwid->pTwi;
+
+ SANITY_CHECK(pTwid);
+
+ // Retrieve interrupt status
+ status = TWI_GetMaskedStatus(pTwi);
+
+ // Byte received
+ if (TWI_STATUS_RXRDY(status)) {
+
+ pTransfer->pData[pTransfer->transferred] = TWI_ReadByte(pTwi);
+ pTransfer->transferred++;
+
+ // Transfer finished ?
+ if (pTransfer->transferred == pTransfer->num) {
+
+ TWI_DisableIt(pTwi, AT91C_TWI_RXRDY);
+ TWI_EnableIt(pTwi, AT91C_TWI_TXCOMP);
+ }
+ // Last byte ?
+ else if (pTransfer->transferred == (pTransfer->num - 1)) {
+
+ TWI_Stop(pTwi);
+ }
+ }
+ // Byte sent
+ else if (TWI_STATUS_TXRDY(status)) {
+
+ // Transfer finished ?
+ if (pTransfer->transferred == pTransfer->num) {
+
+ TWI_DisableIt(pTwi, AT91C_TWI_TXRDY);
+ TWI_EnableIt(pTwi, AT91C_TWI_TXCOMP);
+ TWI_SendSTOPCondition(pTwi);
+ }
+ // Bytes remaining
+ else {
+
+ TWI_WriteByte(pTwi, pTransfer->pData[pTransfer->transferred]);
+ pTransfer->transferred++;
+ }
+ }
+ // Transfer complete
+ else if (TWI_STATUS_TXCOMP(status)) {
+
+ TWI_DisableIt(pTwi, AT91C_TWI_TXCOMP);
+ pTransfer->status = 0;
+ if (pTransfer->callback) {
+
+ pTransfer->callback((Async *) pTransfer);
+ }
+ pTwid->pTransfer = 0;
+ }
+}
+
+//-----------------------------------------------------------------------------
+/// Asynchronously reads data from a slave on the TWI bus. An optional
+/// callback function is triggered when the transfer is complete.
+/// Returns 0 if the transfer has been started; otherwise returns a TWI error
+/// code.
+/// \param pTwid Pointer to a Twid instance.
+/// \param address TWI slave address.
+/// \param iaddress Optional slave internal address.
+/// \param isize Internal address size in bytes.
+/// \param pData Data buffer for storing received bytes.
+/// \param num Number of bytes to read.
+/// \param pAsync Asynchronous transfer descriptor.
+//-----------------------------------------------------------------------------
+unsigned char TWID_Read(
+ Twid *pTwid,
+ unsigned char address,
+ unsigned int iaddress,
+ unsigned char isize,
+ unsigned char *pData,
+ unsigned int num,
+ Async *pAsync)
+{
+ AT91S_TWI *pTwi = pTwid->pTwi;
+ AsyncTwi *pTransfer = (AsyncTwi *) pTwid->pTransfer;
+ unsigned int timeout;
+
+ //TRACE_DEBUG("TWID_Read()\n\r");
+ SANITY_CHECK(pTwid);
+ SANITY_CHECK((address & 0x80) == 0);
+ SANITY_CHECK((iaddress & 0xFF000000) == 0);
+ SANITY_CHECK(isize < 4);
+
+ // Check that no transfer is already pending
+ if (pTransfer) {
+
+ TRACE_ERROR("TWID_Read: A transfer is already pending\n\r");
+ return TWID_ERROR_BUSY;
+ }
+
+ // Set STOP signal if only one byte is sent
+ if (num == 1) {
+
+ TWI_Stop(pTwi);
+ }
+
+ // Asynchronous transfer
+ if (pAsync) {
+
+ // Update the transfer descriptor
+ pTwid->pTransfer = pAsync;
+ pTransfer = (AsyncTwi *) pAsync;
+ pTransfer->status = ASYNC_STATUS_PENDING;
+ pTransfer->pData = pData;
+ pTransfer->num = num;
+ pTransfer->transferred = 0;
+
+ // Enable read interrupt and start the transfer
+ TWI_EnableIt(pTwi, AT91C_TWI_RXRDY);
+ TWI_StartRead(pTwi, address, iaddress, isize);
+ }
+ // Synchronous transfer
+ else {
+
+ // Start read
+ TWI_StartRead(pTwi, address, iaddress, isize);
+
+ // Read all bytes, setting STOP before the last byte
+ while (num > 0) {
+
+ // Last byte
+ if (num == 1) {
+
+ TWI_Stop(pTwi);
+ }
+
+ // Wait for byte then read and store it
+ timeout = 0;
+ while( !TWI_ByteReceived(pTwi) && (++timeout<TWITIMEOUTMAX) );
+ if (timeout == TWITIMEOUTMAX) {
+ TRACE_ERROR("TWID Timeout BR\n\r");
+ return TWID_ERROR_TIMEOUT;
+ }
+ *pData++ = TWI_ReadByte(pTwi);
+ num--;
+ }
+
+ // Wait for transfer to be complete
+ timeout = 0;
+ while( !TWI_TransferComplete(pTwi) && (++timeout<TWITIMEOUTMAX) );
+ if (timeout == TWITIMEOUTMAX) {
+ TRACE_ERROR("TWID Timeout TC\n\r");
+ return TWID_ERROR_TIMEOUT;
+ }
+ }
+
+ return 0;
+}
+
+//------------------------------------------------------------------------------
+/// Asynchronously sends data to a slave on the TWI bus. An optional callback
+/// function is invoked whenever the transfer is complete.
+/// \param pTwid Pointer to a Twid instance.
+/// \param address Slave address.
+/// \param iaddress Optional slave internal address.
+/// \param isize Number of internal address bytes.
+/// \param pData Data buffer to send.
+/// \param num Number of bytes to send.
+/// \param pAsync Pointer to an Asynchronous transfer descriptor.
+//------------------------------------------------------------------------------
+unsigned char TWID_Write(
+ Twid *pTwid,
+ unsigned char address,
+ unsigned int iaddress,
+ unsigned char isize,
+ unsigned char *pData,
+ unsigned int num,
+ Async *pAsync)
+{
+ AT91S_TWI *pTwi = pTwid->pTwi;
+ AsyncTwi *pTransfer = (AsyncTwi *) pTwid->pTransfer;
+ unsigned int timeout;
+
+ //TRACE_DEBUG("TWID_Write()\n\r");
+ //TRACE_DEBUG("0x%X\n\r", pData[0]);
+ SANITY_CHECK(pTwi);
+ SANITY_CHECK((address & 0x80) == 0);
+ SANITY_CHECK((iaddress & 0xFF000000) == 0);
+ SANITY_CHECK(isize < 4);
+
+ // Check that no transfer is already pending
+ if (pTransfer) {
+
+ TRACE_ERROR("TWI_Write: A transfer is already pending\n\r");
+ return TWID_ERROR_BUSY;
+ }
+
+ // Asynchronous transfer
+ if (pAsync) {
+
+ // Update the transfer descriptor
+ pTwid->pTransfer = pAsync;
+ pTransfer = (AsyncTwi *) pAsync;
+ pTransfer->status = ASYNC_STATUS_PENDING;
+ pTransfer->pData = pData;
+ pTransfer->num = num;
+ pTransfer->transferred = 1;
+
+ // Enable write interrupt and start the transfer
+ TWI_StartWrite(pTwi, address, iaddress, isize, *pData);
+ TWI_EnableIt(pTwi, AT91C_TWI_TXRDY);
+ }
+ // Synchronous transfer
+ else {
+
+ // Start write
+ TWI_StartWrite(pTwi, address, iaddress, isize, *pData++);
+ num--;
+
+ // Send all bytes
+ while (num > 0) {
+
+ // Wait before sending the next byte
+ timeout = 0;
+ while( !TWI_ByteSent(pTwi) && (++timeout<TWITIMEOUTMAX) );
+ if (timeout == TWITIMEOUTMAX) {
+ TRACE_ERROR("TWID Timeout BS\n\r");
+ return TWID_ERROR_TIMEOUT;
+ }
+
+ TWI_WriteByte(pTwi, *pData++);
+ num--;
+ }
+
+ // Wait for actual end of transfer
+ timeout = 0;
+
+#ifdef TWI_V3XX
+ // Send a STOP condition
+ TWI_SendSTOPCondition(pTwi);
+#endif
+
+ while( !TWI_TransferComplete(pTwi) && (++timeout<TWITIMEOUTMAX) );
+ if (timeout == TWITIMEOUTMAX) {
+ TRACE_ERROR("TWID Timeout TC2\n\r");
+ return TWID_ERROR_TIMEOUT;
+ }
+
+ }
+
+ return 0;
+}
+
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