urm37: Initial implementation

This driver was tested with the DFRobot URM37 Ultrasonic Ranger, V4.
Both UART and analog access modes are supported.

Signed-off-by: Jon Trulson <jtrulson@ics.com>
Signed-off-by: Abhishek Malik <abhishek.malik@intel.com>

examples/c++/CMakeLists.txt

@@ -148,6 +148,8 @@ add_executable (grovegprs-example grovegprs.cxx)
 add_executable (lm35-example lm35.cxx)
 add_executable (micsv89-example micsv89.cxx)
 add_executable (xbee-example xbee.cxx)
+add_executable (urm37-example urm37.cxx)
+add_executable (urm37-uart-example urm37-uart.cxx)
 
 include_directories (${PROJECT_SOURCE_DIR}/src/hmc5883l)
 include_directories (${PROJECT_SOURCE_DIR}/src/grove)
@@ -261,6 +263,7 @@ include_directories (${PROJECT_SOURCE_DIR}/src/grovegprs)
 include_directories (${PROJECT_SOURCE_DIR}/src/lm35)
 include_directories (${PROJECT_SOURCE_DIR}/src/micsv89)
 include_directories (${PROJECT_SOURCE_DIR}/src/xbee)
+include_directories (${PROJECT_SOURCE_DIR}/src/urm37)
 
 target_link_libraries (hmc5883l-example hmc5883l ${CMAKE_THREAD_LIBS_INIT})
 target_link_libraries (groveled-example grove ${CMAKE_THREAD_LIBS_INIT})
@@ -410,3 +413,5 @@ target_link_libraries (grovegprs-example grovegprs ${CMAKE_THREAD_LIBS_INIT})
 target_link_libraries (lm35-example lm35 ${CMAKE_THREAD_LIBS_INIT})
 target_link_libraries (micsv89-example micsv89 ${CMAKE_THREAD_LIBS_INIT})
 target_link_libraries (xbee-example xbee ${CMAKE_THREAD_LIBS_INIT})
+target_link_libraries (urm37-example urm37 ${CMAKE_THREAD_LIBS_INIT})
+target_link_libraries (urm37-uart-example urm37 ${CMAKE_THREAD_LIBS_INIT})

examples/c++/urm37-uart.cxx

@@ -0,0 +1,66 @@
+/*
+ * Author: Jon Trulson <jtrulson@ics.com>
+ * Copyright (c) 2015 Intel Corporation.
+ *
+ * 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 <iostream>
+#include <signal.h>
+#include "urm37.h"
+
+using namespace std;
+
+bool shouldRun = true;
+
+void sig_handler(int signo)
+{
+  if (signo == SIGINT)
+    shouldRun = false;
+}
+
+int main()
+{
+  signal(SIGINT, sig_handler);
+
+//! [Interesting]
+
+  // Instantiate a URM37 sensor on UART 0, with the reset pin on D2
+  upm::URM37 *sensor = new upm::URM37(0, 2);
+  
+  // Every half a second, sample the URM37 and output the measured
+  // distance in cm, and temperature in degrees C
+
+  while (shouldRun)
+    {
+      cout << "Detected distance (cm): " << sensor->getDistance() << endl;
+      cout << "Temperature (C): " << sensor->getTemperature() << endl;
+      
+      usleep(500000);
+    }
+
+//! [Interesting]
+
+  cout << "Exiting" << endl;
+
+  delete sensor;
+  return 0;
+}

examples/c++/urm37.cxx

@@ -0,0 +1,65 @@
+/*
+ * Author: Jon Trulson <jtrulson@ics.com>
+ * Copyright (c) 2015 Intel Corporation.
+ *
+ * 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 <iostream>
+#include <signal.h>
+#include "urm37.h"
+
+using namespace std;
+
+bool shouldRun = true;
+
+void sig_handler(int signo)
+{
+  if (signo == SIGINT)
+    shouldRun = false;
+}
+
+int main()
+{
+  signal(SIGINT, sig_handler);
+
+//! [Interesting]
+
+  // Instantiate a URM37 sensor on analog pin A0, reset pin on D2,
+  // trigger pin on D3 with an analog reference voltage of 5.0
+  upm::URM37 *sensor = new upm::URM37(0, 2, 3, 5.0);
+
+  // Every half a second, sample the URM37 and output the measured
+  // distance in cm.
+
+  while (shouldRun)
+    {
+      cout << "Detected distance (cm): " << sensor->getDistance() << endl;
+      usleep(500000);
+    }
+
+//! [Interesting]
+
+  cout << "Exiting" << endl;
+
+  delete sensor;
+  return 0;
+}

examples/javascript/urm37-uart.js

@@ -0,0 +1,52 @@
+/*jslint node:true, vars:true, bitwise:true, unparam:true */
+/*jshint unused:true */
+
+/*
+ * Author: Jon Trulson <jtrulson@ics.com>
+ * Copyright (c) 2015 Intel Corporation.
+ *
+ * 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.
+ */
+
+
+var sensorObj = require('jsupm_urm37');
+
+// Instantiate a URM37 sensor on UART 0, with the reset pin on D2
+var sensor = new sensorObj.URM37(0, 2);
+
+// Every half a second, sample the URM37 and output the measured
+// distance in cm, and temperature in degrees C
+
+setInterval(function()
+{
+    console.log("Detected distance (cm): " + sensor.getDistance());
+    console.log("Temperature (C): " + sensor.getTemperature());
+}, 500);
+
+// exit on ^C
+process.on('SIGINT', function()
+{
+    sensor = null;
+    sensorObj.cleanUp();
+    sensorObj = null;
+    console.log("Exiting.");
+    process.exit(0);
+});
+

examples/javascript/urm37.js

@@ -0,0 +1,52 @@
+/*jslint node:true, vars:true, bitwise:true, unparam:true */
+/*jshint unused:true */
+
+/*
+ * Author: Jon Trulson <jtrulson@ics.com>
+ * Copyright (c) 2015 Intel Corporation.
+ *
+ * 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.
+ */
+
+
+var sensorObj = require('jsupm_urm37');
+
+// Instantiate a URM37 sensor on analog pin A0, reset pin on D2,
+// trigger pin on D3 with an analog reference voltage of 5.0
+var sensor = new sensorObj.URM37(0, 2, 3, 5.0);
+
+// Every half a second, sample the URM37 and output the measured
+// distance in cm.
+
+setInterval(function()
+{
+    console.log("Detected distance (cm): " + sensor.getDistance());
+}, 500);
+
+// exit on ^C
+process.on('SIGINT', function()
+{
+    sensor = null;
+    sensorObj.cleanUp();
+    sensorObj = null;
+    console.log("Exiting.");
+    process.exit(0);
+});
+

examples/python/urm37-uart.py

@@ -0,0 +1,50 @@
+#!/usr/bin/python
+# Author: Jon Trulson <jtrulson@ics.com>
+# Copyright (c) 2015 Intel Corporation.
+#
+# 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.
+
+import time, sys, signal, atexit
+import pyupm_urm37 as sensorObj
+
+# Instantiate a URM37 sensor on UART 0, with the reset pin on D2
+sensor = sensorObj.URM37(0, 2)
+
+## Exit handlers ##
+# This function stops python from printing a stacktrace when you hit control-C
+def SIGINTHandler(signum, frame):
+	raise SystemExit
+
+# This function lets you run code on exit
+def exitHandler():
+	print "Exiting"
+	sys.exit(0)
+
+# Register exit handlers
+atexit.register(exitHandler)
+signal.signal(signal.SIGINT, SIGINTHandler)
+
+# Every half a second, sample the URM37 and output the measured
+# distance in cm, and temperature in degrees C
+
+while (1):
+        print "Detected distance (cm):", sensor.getDistance()
+        print "Temperature (C):", sensor.getTemperature()
+	time.sleep(.5)

examples/python/urm37.py

@@ -0,0 +1,50 @@
+#!/usr/bin/python
+# Author: Jon Trulson <jtrulson@ics.com>
+# Copyright (c) 2015 Intel Corporation.
+#
+# 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.
+
+import time, sys, signal, atexit
+import pyupm_urm37 as sensorObj
+
+# Instantiate a URM37 sensor on analog pin A0, reset pin on D2,
+# trigger pin on D3 with an analog reference voltage of 5.0
+sensor = sensorObj.URM37(0, 2, 3, 5.0)
+
+## Exit handlers ##
+# This function stops python from printing a stacktrace when you hit control-C
+def SIGINTHandler(signum, frame):
+	raise SystemExit
+
+# This function lets you run code on exit
+def exitHandler():
+	print "Exiting"
+	sys.exit(0)
+
+# Register exit handlers
+atexit.register(exitHandler)
+signal.signal(signal.SIGINT, SIGINTHandler)
+
+# Every half a second, sample the URM37 and output the measured
+# distance in cm.
+
+while (1):
+        print "Detected distance (cm):", sensor.getDistance()
+	time.sleep(.5)

src/urm37/CMakeLists.txt

@@ -0,0 +1,5 @@
+set (libname "urm37")
+set (libdescription "upm DFRobot URM37 Ultrasonic ranger")
+set (module_src ${libname}.cxx)
+set (module_h ${libname}.h)
+upm_module_init()

src/urm37/javaupm_urm37.i

@@ -0,0 +1,10 @@
+%module javaupm_urm37
+%include "../upm.i"
+%include "std_string.i"
+
+%{
+    #include "urm37.h"
+%}
+
+%include "urm37.h"
+

src/urm37/jsupm_urm37.i

@@ -0,0 +1,10 @@
+%module jsupm_urm37
+%include "../upm.i"
+%include "std_string.i"
+
+%{
+    #include "urm37.h"
+%}
+
+%include "urm37.h"
+

src/urm37/pyupm_urm37.i

@@ -0,0 +1,11 @@
+%module pyupm_urm37
+%include "../upm.i"
+%include "std_string.i"
+
+%feature("autodoc", "3");
+
+%{
+    #include "urm37.h"
+%}
+%include "urm37.h"
+

src/urm37/urm37.cxx

@@ -0,0 +1,318 @@
+/*
+ * Author: Jon Trulson <jtrulson@ics.com>
+ * Copyright (c) 2015 Intel Corporation.
+ *
+ * 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 <iostream>
+
+#include "urm37.h"
+
+using namespace upm;
+using namespace std;
+
+static const int waitTimeout = 1000;
+static const int maxRetries = 10;
+
+URM37::URM37(int aPin, int resetPin, int triggerPin, float aref) :
+  m_uart(0), m_aio(new mraa::Aio(aPin)), m_gpioReset(resetPin), 
+  m_gpioTrigger(new mraa::Gpio(triggerPin))
+{
+  m_analogMode = true;
+
+  m_aRes = (1 << m_aio->getBit());
+  m_aref = aref;
+
+  m_gpioTrigger->dir(mraa::DIR_OUT);
+
+  // setup trigger for mmapped access, not a big deal if this fails
+  m_gpioTrigger->useMmap(true);
+
+  // trigger high
+  m_gpioTrigger->write(1);
+
+  init();
+}
+
+URM37::URM37(int uart, int resetPin) :
+  m_uart(new mraa::Uart(uart)), m_aio(0), m_gpioReset(resetPin), 
+  m_gpioTrigger(0)
+{
+  m_analogMode = false;
+
+  m_aRes = 0;
+  m_aref = 0;
+
+  // 9600 baud is the only support baud rate...
+  if (m_uart->setBaudRate(9600))
+    {
+      throw std::runtime_error(string(__FUNCTION__) +
+                               ": setBaudRate(9600) failed");
+      return;
+    }
+
+  init();
+}
+
+URM37::~URM37()
+{
+  if (m_uart)
+    delete m_uart;
+  if (m_aio)
+    delete m_aio;
+  if(m_gpioTrigger)
+    delete m_gpioTrigger;
+}
+
+void URM37::init()
+{
+  m_gpioReset.dir(mraa::DIR_OUT);
+
+  // reset the device
+  reset();
+}
+
+void URM37::reset()
+{
+  // toggle reset
+  m_gpioReset.write(0);
+  usleep(100);
+  m_gpioReset.write(1);
+  // wait for reset to complete
+  sleep(3);
+}
+
+bool URM37::dataAvailable(unsigned int millis)
+{
+  return m_uart->dataAvailable(millis);
+}
+
+std::string URM37::readDataStr(int len)
+{
+  return m_uart->readStr(len);
+}
+
+int URM37::writeDataStr(std::string data)
+{
+  m_uart->flush();
+  return m_uart->writeStr(data);
+}
+
+float URM37::getDistance(int degrees)
+{
+  // analog mode
+  if (m_analogMode)
+    {
+      m_gpioTrigger->write(0);
+      int val = m_aio->read();
+      m_gpioTrigger->write(1);
+      
+      float mVolts = (float(val) * (m_aref / m_aRes)) * 1000.0;
+      
+      // 6.8mV per CM
+      return (mVolts / 6.8);
+    }
+
+  // UART mode
+  // query distance cmd sequence
+  uint8_t deg = (uint8_t)(degrees / 6);
+  if (deg > 46)
+    throw std::out_of_range(string(__FUNCTION__) +
+                            ": degrees out of range, must be 0-270");
+
+  string cmd;
+  uint8_t cksum = 0x22 + deg + 0x00;
+  cmd.push_back(0x22);
+  cmd.push_back(deg);
+  cmd.push_back(0x00);
+  cmd.push_back(cksum);
+  
+  string resp = sendCommand(cmd);
+
+  if (resp.empty())
+    {
+      throw std::runtime_error(string(__FUNCTION__) +
+                               ": sendCommand() failed");
+      return 0.0;
+    }
+
+  uint8_t h = (uint8_t)resp[1];
+  uint8_t l = (uint8_t)resp[2];
+
+  float distance = float((h << 8) | l);
+
+  return (distance);
+}
+
+float URM37::getTemperature()
+{
+  if (m_analogMode)
+    {
+      throw std::runtime_error(string(__FUNCTION__) +
+                 ": Temperature measurement not available in analog mode");
+
+      return 0.0;
+    }
+
+  // query temperature cmd sequence
+  string cmd;
+  cmd.push_back(0x11);
+  cmd.push_back(0x00);
+  cmd.push_back(0x00);
+  cmd.push_back(0x11);
+  
+  string resp = sendCommand(cmd);
+
+  if (resp.empty())
+    {
+      throw std::runtime_error(string(__FUNCTION__) +
+                               ": sendCommand() failed");
+      return 0.0;
+    }
+
+  uint8_t h = (uint8_t)resp[1];
+  uint8_t l = (uint8_t)resp[2];
+
+  float temp;
+  temp = float((h & 0x0f) * 256 + l) / 10.0;
+  if (h & 0xf0)
+    temp *= -1;
+
+  return (temp);
+}
+
+uint8_t URM37::readEEPROM(uint8_t addr)
+{
+  if (m_analogMode)
+    {
+      throw std::runtime_error(string(__FUNCTION__) +
+                 ": readEEPROM() is not possible in analog mode");
+
+      return 0;
+    }
+
+  if (addr > 0x04)
+    throw std::out_of_range(string(__FUNCTION__) +
+                            ": addr must be between 0x00-0x04");
+
+  string cmd;
+  uint8_t cksum = 0x33 + addr + 0x00;
+  cmd.push_back(0x33);
+  cmd.push_back(addr);
+  cmd.push_back(0x00);
+  cmd.push_back(cksum);
+
+  string resp = sendCommand(cmd);
+
+  if (resp.empty())
+    {
+      throw std::runtime_error(string(__FUNCTION__) +
+                               ": sendCommand() failed");
+      return 0;
+    }
+
+  return resp[2];
+}
+
+void URM37::writeEEPROM(uint8_t addr, uint8_t value)
+{
+  if (m_analogMode)
+    {
+      throw std::runtime_error(string(__FUNCTION__) +
+                 ": writeEEPROM() is not possible in analog mode");
+
+      return;
+    }
+
+  if (addr > 0x04)
+    throw std::out_of_range(string(__FUNCTION__) +
+                            ": addr must be between 0x00-0x04");
+
+  string cmd;
+  uint8_t cksum = 0x44 + addr + value;
+  cmd.push_back(0x44);
+  cmd.push_back(addr);
+  cmd.push_back(value);
+  cmd.push_back(cksum);
+
+  string resp = sendCommand(cmd);
+
+  if (resp.empty())
+    {
+      throw std::runtime_error(string(__FUNCTION__) +
+                               ": sendCommand() failed");
+      return;
+    }
+
+  return;
+}
+
+string URM37::sendCommand(string cmd)
+{
+  if (m_analogMode)
+    {
+      throw std::runtime_error(string(__FUNCTION__) +
+                               ": can only be executed in UART mode");
+
+      return "";
+    }
+
+  int tries = 0;
+  string resp;
+
+  while (tries++ < maxRetries)
+    {
+      writeDataStr(cmd);
+      if (!dataAvailable(waitTimeout))
+        {
+          cerr << __FUNCTION__ << ": Timed out waiting for response" << endl;
+          continue;
+        }
+      
+      resp = readDataStr(8);
+      
+      // verify size
+      if (resp.size() != 4)
+        {
+          cerr << __FUNCTION__ << ": Invalid returned packet size" << endl;
+          continue;
+        }
+      else
+        {
+          // we have data, verify cksum, return the response if it's
+          // good, retry otherwise
+          uint8_t cksum = (uint8_t)(resp[0] + resp[1] + resp[2]);
+
+          if ((uint8_t)resp[3] != cksum)
+            {
+              cerr << __FUNCTION__ << ": cksum failure" << endl;
+              continue;
+            }
+
+          // else, we are good to go
+          return resp;
+        }
+    }
+
+  // :(
+  return "";
+}
+

src/urm37/urm37.h

@@ -0,0 +1,204 @@
+/*
+ * Author: Jon Trulson <jtrulson@ics.com>
+ * Copyright (c) 2015 Intel Corporation.
+ *
+ * Thanks to Adafruit for supplying a google translated version of the
+ * Chinese datasheet and some clues in their code.
+ *
+ * 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.
+ */
+#pragma once
+
+#include <string>
+#include <iostream>
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+
+#include <mraa/common.hpp>
+#include <mraa/uart.hpp>
+#include <mraa/aio.hpp>
+#include <mraa/gpio.hpp>
+
+#define URM37_DEFAULT_UART 0
+
+namespace upm {
+    /**
+     * @brief DFRobot URM37 Ultrasonic Ranger
+     * @defgroup urm37 libupm-urm37
+     * @ingroup dfrobot uart gpio ainput sound
+     */
+
+    /**
+     * @library urm37
+     * @sensor urm37
+     * @comname DFRobot URM37 Ultrasonic Ranger
+     * @type sound
+     * @man dfrobot
+     * @con uart ainput gpio
+     * @web http://www.dfrobot.com/index.php?route=product/product&product_id=53
+     *
+     * @brief API for the DFRobot URM37 Ultrasonic Ranger
+     *
+     * The driver was tested with the DFRobot URM37 Ultrasonic Ranger,
+     * V4.  It has a range of between 5 and 500 centimeters (cm).  It
+     * supports both analog distance measurement, and UART based
+     * temperature and distance measurements.  This driver does not
+     * support PWM measurement mode.
+     *
+     * For UART operation, the only supported baud rate is 9600.  In
+     * addition, you must ensure that the UART TX/RX pins are
+     * configured for TTL operation (the factory default) rather than
+     * RS232 operation, or permanent damage to your URM37 and/or MCU
+     * will result.  On power up, the LED indicator will blink one
+     * long pulse, followed by one short pulse to indicate TTL
+     * operation.  See the DFRobot wiki for more information:
+     *
+     * (https://www.dfrobot.com/wiki/index.php?title=URM37_V4.0_Ultrasonic_Sensor_%28SKU:SEN0001%29)
+     *
+     * An example using analog mode
+     * @snippet urm37.cxx Interesting
+     * An example using UART mode
+     * @snippet urm37-uart.cxx Interesting
+     */
+
+  class URM37 {
+  public:
+
+    /**
+     * URM37 object constructor (Analog mode)
+     *
+     * @param aPin Analog pin to use
+     * @param resetPin GPIO pin to use for reset
+     * @param triggerPin GPIO pin to use for triggering a distance measurement
+     * @param aref The analog reference voltage, default 5.0
+     */
+    URM37(int aPin, int resetPin, int triggerPin, float aref=5.0);
+
+    /**
+     * URM37 object constructor (UART mode)
+     *
+     * @param uart Default UART to use (0 or 1).
+     * @param resetPin GPIO pin to use for reset
+     */
+    URM37(int uart, int resetPin);
+
+    /**
+     * URM37 object destructor
+     */
+    ~URM37();
+
+    /**
+     * Reset the device.  This will take approximately 3 seconds to
+     * complete.
+     *
+     */
+    void reset();
+
+    /**
+     * Get the distance measurement.  A return value of 65535.0
+     * in UART mode indicates an invalid measurement.
+     *
+     * @param degrees in UART mode, this specifies the degrees to turn
+     * an attached PWM servo connected to the MOTO output on the
+     * URM37.  Default is 0.  Valid values are 0-270.  This option is
+     * ignored in analog mode.
+     * @return The measured distance in cm
+     */
+    float getDistance(int degrees=0);
+
+    /**
+     * Get the temperature measurement.  This is only valid in UART mode.
+     *
+     * @return The measured temperature in degrees C
+     */
+    float getTemperature();
+
+    /**
+     * In UART mode only, read a value from the EEPROM and return it.
+     *
+     * @param addr The address in the EEPROM to read.  Valid values
+     * are between 0x00-0x04.
+     * @return The EEPROM value at addr
+     */
+    uint8_t readEEPROM(uint8_t addr);
+
+    /**
+     * In UART mode only, write a value into an address on the EEPROM.
+     *
+     * @param addr The address in the EEPROM to write.  Valid values
+     * are between 0x00-0x04.
+     * @param value The value to write
+     * @return The EEPROM value at addr
+     */
+    void writeEEPROM(uint8_t addr, uint8_t value);
+
+  protected:
+    mraa::Uart *m_uart;
+    mraa::Aio *m_aio;
+    mraa::Gpio *m_gpioTrigger;
+    mraa::Gpio m_gpioReset;
+
+    // initialize reset gpio and call reset
+    void init();
+
+    // send a serial command and return a 4 byte response (UART mode only)
+    std::string sendCommand(std::string cmd);
+
+  private:
+    /**
+     * Checks to see if there is data aavailable for reading
+     *
+     * @param millis Number of milliseconds to wait; 0 means no waiting
+     * @return true if there is data available for reading
+     */
+    bool dataAvailable(unsigned int millis);
+
+    /**
+     * Reads any available data and returns it in a std::string. Note:
+     * the call blocks until data is available for reading. Use
+     * dataAvailable() to determine whether there is data available
+     * beforehand, to avoid blocking.
+     *
+     * @param len Maximum length of the data to be returned
+     * @return Number of bytes read
+     */
+    std::string readDataStr(int len);
+
+    /**
+     * Writes the std:string data to the device.  If you are writing a
+     * command, be sure to terminate it with a carriage return (\r)
+     *
+     * @param data Buffer to write to the device
+     * @return Number of bytes written
+     */
+    int writeDataStr(std::string data);
+
+    // analog or UART mode
+    bool m_analogMode;
+
+    // analog reference and resolution
+    float m_aref;
+    int m_aRes;
+  };
+}
+
+