diff options
Diffstat (limited to 'components/sensors/ms5540b/ms5540b.c')
| -rw-r--r-- | components/sensors/ms5540b/ms5540b.c | 327 |
1 files changed, 327 insertions, 0 deletions
diff --git a/components/sensors/ms5540b/ms5540b.c b/components/sensors/ms5540b/ms5540b.c new file mode 100644 index 0000000..ae6b3cf --- /dev/null +++ b/components/sensors/ms5540b/ms5540b.c @@ -0,0 +1,327 @@ +/* ----------------------------------------------------------------------------
+ * 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.
+ * ----------------------------------------------------------------------------
+ */
+
+#undef TRACE_LEVEL
+#define TRACE_LEVEL 0
+
+//------------------------------------------------------------------------------
+// Headers
+//------------------------------------------------------------------------------
+
+#include "ms5540b.h"
+#include <spi/spi.h>
+#include <utility/trace.h>
+#include <utility/assert.h>
+
+//------------------------------------------------------------------------------
+// Local definitions
+//------------------------------------------------------------------------------
+
+/// Baudrate divisor value.
+#define SCBR (0xFF << 8)
+
+/// Command for retrieving calibration word 1.
+#define CMD_WORD_1 /*0x0EA8*/ 0x1D50
+/// Command for retrieving calibration word 2.
+#define CMD_WORD_2 /*0x0EB0*/ 0x1D60
+/// Command for retrieving calibration word 3.
+#define CMD_WORD_3 /*0x0EC8*/ 0x1D90
+/// Command for retrieving calibration word 4.
+#define CMD_WORD_4 /*0x0ED0*/ 0x1DA0
+/// Command for starting a pressure conversion.
+#define CMD_PRES 0x0F40
+/// Command for starting a temperature conversion.
+#define CMD_TEMP 0x0F20
+
+/// Driver is idle.
+#define STATE_IDLE 0
+/// Driver is performing a temperature conversion.
+#define STATE_TEMP 1
+/// Driver is performing a pressure conversion.
+#define STATE_PRES 2
+
+//------------------------------------------------------------------------------
+// Local variables
+//------------------------------------------------------------------------------
+
+/// SPI peripheral used to connect to the MS5540B.
+static AT91S_SPI *lpSpi;
+
+/// Chip select configured for the sensor.
+static unsigned int lCs;
+
+/// Calibration coefficients.
+static unsigned short lCoeffs[6];
+
+/// Current driver state.
+static unsigned char lState;
+
+/// Last temperature measurement made.
+static unsigned short lD2 = 0;
+
+//------------------------------------------------------------------------------
+// Local functions
+//------------------------------------------------------------------------------
+
+//------------------------------------------------------------------------------
+/// Reads & returns the result of the last command.
+//------------------------------------------------------------------------------
+unsigned short Fetch(void)
+{
+ unsigned short result;
+
+ // Configure SPI to receive the first 8 data bytes
+ SPI_ConfigureNPCS(lpSpi, lCs, AT91C_SPI_BITS_8 | SCBR);
+
+ // Read the first 8 bytes
+ SPI_Write(lpSpi, lCs, 0);
+ while (!SPI_IsFinished(lpSpi));
+ result = (SPI_Read(lpSpi) & 0xFF) << 8;
+
+ // Configure SPI to receive the next 8 bytes (with one dummy byte)
+ SPI_ConfigureNPCS(lpSpi, lCs, AT91C_SPI_BITS_9 | SCBR);
+
+ // Read the last 8 bytes
+ SPI_Write(lpSpi, lCs, 0);
+ while (!SPI_IsFinished(lpSpi));
+ result |= (SPI_Read(lpSpi) >> 1) & 0xFF;
+
+ TRACE_DEBUG("MS5540B_Fetch: Result = %d\n\r", result);
+
+ return result;
+}
+
+//------------------------------------------------------------------------------
+/// Resets the sensor.
+//------------------------------------------------------------------------------
+static void Reset()
+{
+ const unsigned short pCommand[] = {0x00AA, 0x1540};
+
+ SANITY_CHECK(SPI_IsFinished(lpSpi));
+
+ TRACE_DEBUG("MS5540B_Reset()\n\r");
+
+ // Configure chip select for 8 bits transfer
+ SPI_ConfigureNPCS(lpSpi, lCs, AT91C_SPI_NCPHA | AT91C_SPI_BITS_8 | SCBR);
+
+ // Transfer first 8 bits
+ SPI_Write(lpSpi, lCs, pCommand[0]);
+ while (!SPI_IsFinished(lpSpi));
+
+ // Configure chip select for 13 bits transfer
+ SPI_ConfigureNPCS(lpSpi, lCs, AT91C_SPI_NCPHA | AT91C_SPI_BITS_13 | SCBR);
+
+ // Transfer remaining 13 bits
+ SPI_Write(lpSpi, lCs, pCommand[1]);
+ while (!SPI_IsFinished(lpSpi));
+}
+
+//------------------------------------------------------------------------------
+/// Reads and returns a calibration word from the sensor.
+/// \param cmd Command to retrieve desired word (CMD_WORD_1 ... CMD_WORD_4).
+//------------------------------------------------------------------------------
+static unsigned short ReadCalibrationWord(unsigned short cmd)
+{
+ TRACE_DEBUG("MS5540B_ReadCalibrationWord(0x%04X)\n\r", cmd);
+
+ SANITY_CHECK((cmd == CMD_WORD_1)
+ || (cmd == CMD_WORD_2)
+ || (cmd == CMD_WORD_3)
+ || (cmd == CMD_WORD_4));
+ SANITY_CHECK(SPI_IsFinished(lpSpi));
+
+ // Configure SPI to send the command
+ SPI_ConfigureNPCS(lpSpi, lCs, AT91C_SPI_NCPHA | AT91C_SPI_BITS_13 | SCBR);
+
+ // Transfer command
+ SPI_Write(lpSpi, lCs, cmd);
+ while (!SPI_IsFinished(lpSpi));
+
+ // Read & return result
+ return Fetch();
+}
+
+//------------------------------------------------------------------------------
+// Global functions
+//------------------------------------------------------------------------------
+
+//------------------------------------------------------------------------------
+/// Initializes a MS5540B sensor. The provided SPI peripheral is configured
+/// for the sensor (using the given chip select), and the calibration data
+/// is extracted.
+/// The sensor MUST BE CLOCKED before calling this function. It can then be
+/// unclocked in-between measurements.
+/// In addition, the SPI peripheral must be configured properly prior to calling
+/// this function.
+/// \param pSpi Pointer to the SPI peripheral connected to the MS5540B.
+/// \param cs Chip select value to use.
+//------------------------------------------------------------------------------
+void MS5540B_Initialize(AT91S_SPI *pSpi, unsigned char cs)
+{
+ unsigned short word1, word2, word3, word4;
+
+ SANITY_CHECK(pSpi);
+
+ TRACE_DEBUG("MS5540B_Initialize(0x%08X, %d)\n\r", pSpi, cs);
+
+ // Store SPI information
+ lpSpi = pSpi;
+ lCs = cs;
+ lState = STATE_IDLE;
+
+ // Reset the sensor
+ Reset();
+
+ // Extract calibration data from the sensor
+ word1 = ReadCalibrationWord(CMD_WORD_1);
+ word2 = ReadCalibrationWord(CMD_WORD_2);
+ word3 = ReadCalibrationWord(CMD_WORD_3);
+ word4 = ReadCalibrationWord(CMD_WORD_4);
+
+ TRACE_DEBUG("Word1 = %d\n\r", word1);
+ TRACE_DEBUG("Word2 = %d\n\r", word2);
+ TRACE_DEBUG("Word3 = %d\n\r", word3);
+ TRACE_DEBUG("Word4 = %d\n\r", word4);
+
+ // Compute coefficients
+ lCoeffs[0] = (word1 >> 1) & 0x7FFF;
+ lCoeffs[1] = (word4 & 0x003F) | ((word3 & 0x003F) << 6);
+ lCoeffs[2] = (word4 >> 6) & 0x03FF;
+ lCoeffs[3] = (word3 >> 6) & 0x03FF;
+ lCoeffs[4] = ((word2 >> 6) | ((word1 & 0x0001) << 10)) & 0x07FF;
+ lCoeffs[5] = word2 & 0x003F;
+
+ TRACE_DEBUG("C1 = %d\n\r", lCoeffs[0]);
+ TRACE_DEBUG("C2 = %d\n\r", lCoeffs[1]);
+ TRACE_DEBUG("C3 = %d\n\r", lCoeffs[2]);
+ TRACE_DEBUG("C4 = %d\n\r", lCoeffs[3]);
+ TRACE_DEBUG("C5 = %d\n\r", lCoeffs[4]);
+ TRACE_DEBUG("C6 = %d\n\r", lCoeffs[5]);
+}
+
+//------------------------------------------------------------------------------
+/// Starts a temperature acquisition. This function returns as soon as the
+/// command has been sent.
+/// The conversion must be completed by calling MS5540B_ConversionFinished()
+/// whenever the device signals the end-of-conversion.
+//------------------------------------------------------------------------------
+void MS5540B_AcquireTemperature(void)
+{
+ SANITY_CHECK(lState == STATE_IDLE);
+
+ TRACE_DEBUG("MS5540B_AcquireTemperature()\n\r");
+
+ // Configure SPI for 12 bits transfers
+ SPI_ConfigureNPCS(lpSpi, lCs, AT91C_SPI_NCPHA | AT91C_SPI_BITS_12 | AT91C_SPI_CSAAT | SCBR);
+
+ // Send command
+ SPI_Write(lpSpi, lCs, CMD_TEMP);
+ while (!SPI_IsFinished(lpSpi));
+
+ // Update driver state
+ lState = STATE_TEMP;
+}
+
+//------------------------------------------------------------------------------
+/// Starts a pressure acquisition. This function returns as soon as the
+/// command has been sent.
+/// The conversion must be completed by calling MS5540B_ConversionFinished()
+/// whenever the device signals the end-of-conversion.
+/// A temperature measurement must have been performed prior to calling this
+/// function.
+//------------------------------------------------------------------------------
+void MS5540B_AcquirePressure(void)
+{
+ SANITY_CHECK(lState == STATE_IDLE);
+ SANITY_CHECK(lD2 != 0);
+
+ TRACE_DEBUG("MS5540B_AcquirePressure()\n\r");
+
+ // Configure SPI for 12 bits transfers
+ SPI_ConfigureNPCS(lpSpi, lCs, AT91C_SPI_NCPHA | AT91C_SPI_BITS_12 | AT91C_SPI_CSAAT | SCBR);
+
+ // Send command
+ SPI_Write(lpSpi, lCs, CMD_PRES);
+ while (!SPI_IsFinished(lpSpi));
+
+ // Update driver state
+ lState = STATE_PRES;
+}
+
+//------------------------------------------------------------------------------
+/// Fetches and returns the result of the last conversion from the sensor. This
+/// function must only be called whenever the MS5540B signals that the
+/// conversion is completed with the DOUT signal line.
+/// The temperature returned is 10*C° (e.g. 31.4°C -> 314).
+//------------------------------------------------------------------------------
+unsigned short MS5540B_ConversionFinished(void)
+{
+ signed short result;
+ signed short dT;
+ unsigned short offset, sensitivity, x;
+
+ SANITY_CHECK((lState == STATE_TEMP) || (lState == STATE_PRES));
+
+ TRACE_DEBUG("MS5540B_ConversionFinished()\n\r");
+
+ // Retrieve conversion result
+ result = (signed short) Fetch();
+
+ // Correct result using calibration data
+ if (lState == STATE_TEMP) {
+
+ lD2 = result;
+ dT = result - 8 * lCoeffs[4] - 20224;
+ result = 200 + dT * (lCoeffs[5] + 50) / 1024;
+ TRACE_DEBUG("D2 = %d\n\r", lD2);
+ TRACE_DEBUG("dT = %d\n\r", dT);
+ TRACE_DEBUG("TEMP = %d\n\r", result);
+ }
+ else {
+
+ TRACE_DEBUG("D1 = %d\n\r", result);
+ dT = lD2 - 8 * lCoeffs[4] - 20224;
+ offset = lCoeffs[1] * 4 + ((lCoeffs[3] - 512) * dT) / 4096;
+ sensitivity = lCoeffs[0] + (lCoeffs[2] * dT) / 1024 + 24576;
+ x = (sensitivity * (result - 7168)) / 16384 - offset;
+ result = x * 10 / 32 + 2500;
+ TRACE_DEBUG("dT = %d\n\r", dT);
+ TRACE_DEBUG("OFF = %d\n\r", offset);
+ TRACE_DEBUG("SENS = %d\n\r", sensitivity);
+ TRACE_DEBUG("X = %d\n\r", x);
+ TRACE_DEBUG("P = %d\n\r", result);
+ }
+
+ // Update driver state
+ lState = STATE_IDLE;
+
+ return result;
+}
+
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