si114x: Initial implementation

This module implements support for the Adafruit UV sensor:
https://www.adafruit.com/products/1777

Signed-off-by: Jon Trulson <jtrulson@ics.com>
Signed-off-by: Zion Orent <zorent@ics.com>
Signed-off-by: Mihai Tudor Panu <mihai.tudor.panu@intel.com>

src/si114x/si114x.cxx

@@ -0,0 +1,190 @@
+/*
+ * Author: Jon Trulson <jtrulson@ics.com>
+ * Copyright (c) 2015 Intel Corporation.
+ *
+ * Thanks to Adafruit for some important clues
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include <unistd.h>
+#include <math.h>
+#include <iostream>
+#include <string>
+
+#include "si114x.h"
+
+using namespace upm;
+using namespace std;
+
+
+SI114X::SI114X(int bus, uint8_t address)
+{
+  m_addr = address;
+  m_uvIndex = 0;
+
+  // setup our i2c link
+  if ( !(m_i2c = mraa_i2c_init(bus)) )
+    {
+      cerr << "SI114X: mraa_i2c_init() failed." << endl;
+      return;
+    }
+      
+  mraa_result_t rv;
+  
+  if ( (rv = mraa_i2c_address(m_i2c, m_addr)) != MRAA_SUCCESS)
+    {
+      cerr << "SI114X: Could not initialize i2c bus. " << endl;
+      mraa_result_print(rv);
+      return;
+    }
+
+  // The data sheet recommends setting the UV calibration values to
+  // 0x7b, 0x6b, 0x01, and 0x00, however the adafruit code uses a
+  // different set of values, presumably calibrated to their specific
+  // implementation.  We will use those defaults here, as this was
+  // developed on an adafruit device.  
+
+  // Use setUVCalibration() to set a different set of values before
+  // calling init() if you need different values.
+
+  setUVCalibration(0x29, 0x89, 0x02, 0x00);
+}
+
+SI114X::~SI114X()
+{
+  mraa_i2c_stop(m_i2c);
+}
+
+bool SI114X::writeByte(uint8_t reg, uint8_t byte)
+{
+  mraa_result_t rv = mraa_i2c_write_byte_data(m_i2c, byte, reg);
+
+  if (rv != MRAA_SUCCESS)
+    {
+      cerr << __FUNCTION__ << ": mraa_i2c_write_byte() failed." << endl;
+      mraa_result_print(rv);
+      return false;
+    }
+
+  return true;
+}
+
+uint8_t SI114X::readByte(uint8_t reg)
+{
+  return mraa_i2c_read_byte_data(m_i2c, reg);
+}
+
+uint16_t SI114X::readWord(uint8_t reg)
+{
+  return mraa_i2c_read_word_data(m_i2c, reg);
+}
+
+void SI114X::setUVCalibration(uint8_t uvcoeff0, uint8_t uvcoeff1, 
+                              uint8_t uvcoeff2, uint8_t uvcoeff3)
+{
+  m_uv_cal[0] = uvcoeff0;
+  m_uv_cal[1] = uvcoeff1;
+  m_uv_cal[2] = uvcoeff2;
+  m_uv_cal[3] = uvcoeff3; 
+};
+
+
+void SI114X::writeParam(SI114X_PARAM_T param, uint8_t value)
+{
+  // write a parameter to the RAM parameter area
+
+  // We write the value to the PARAM_WR register, then execute a
+  // PARAM_WRITE command
+
+  writeByte(REG_PARAM_WR, value);
+
+  // now write it to parameter memory
+  writeByte(REG_COMMAND, CMD_PARAM_SET | param);
+}
+
+uint8_t SI114X::readParam(SI114X_PARAM_T param)
+{
+  // get the parameter into register REG_PARAM_READ, then read and return it.
+
+  writeByte(REG_COMMAND, CMD_PARAM_QUERY | param);
+  return readByte(REG_PARAM_READ);
+}
+
+void SI114X::reset()
+{
+  // reset the device 
+
+  // zero out measuring rate
+  writeByte(REG_MEAS_RATE0, 0);
+  writeByte(REG_MEAS_RATE1, 0);
+
+  // disable IRQ MODES
+  // these are undocumented in the datasheet, but mentioned in Adafruit's code
+  writeByte(REG_IRQ_MODE1, 0);
+  writeByte(REG_IRQ_MODE2, 0);
+  
+  // turn off interrupts
+  writeByte(REG_INT_CFG, 0);
+  writeByte(REG_IRQ_STATUS, 0xff);
+
+  // send a reset
+  writeByte(REG_COMMAND, CMD_RESET);
+  usleep(100);
+
+  // set the hardware key
+  writeByte(REG_HW_KEY, SI114X_HW_KEY);
+  usleep(100);
+}
+
+void SI114X::initialize()
+{
+  // initialize the device
+
+  // first, reset it
+  reset();
+
+  // UV coefficients
+  writeByte(REG_UCOEF0, m_uv_cal[0]);
+  writeByte(REG_UCOEF1, m_uv_cal[1]);
+  writeByte(REG_UCOEF2, m_uv_cal[2]);
+  writeByte(REG_UCOEF3, m_uv_cal[3]);
+  
+  // enable UV sensor only for now
+  writeParam(PARAM_CHLIST, CHLIST_EN_UV);
+
+  // auto-measure speed - slowest - (rate * 31.25us)
+  writeByte(REG_MEAS_RATE0, 0xff); // 7.9ms
+
+  // set autorun
+  writeByte(REG_COMMAND, CMD_ALS_AUTO);
+}
+
+void SI114X::update()
+{
+  // for now, just update the UV Index member variable
+  uint16_t uvi = readWord(REG_AUX_UVINDEX0);
+
+  m_uvIndex = float(uvi) / 100.0;
+
+  // Add any further data gets() here
+
+  return;
+}