urm37: Add C library for this sensor

Added a C implementation for this sensor.  The C++ library was changed
to just wrap the C library calls.

Signed-off-by: Jon Trulson <jtrulson@ics.com>

examples/c++/urm37-uart.cxx

@@ -53,7 +53,8 @@ int main()
     {
       cout << "Detected distance (cm): " << sensor->getDistance() << endl;
       cout << "Temperature (C): " << sensor->getTemperature() << endl;
-      
+      cout << endl;
+
       usleep(500000);
     }
 

examples/c/CMakeLists.txt

@@ -90,3 +90,5 @@ add_example (dfrph)
 add_example (vk2828u7)
 add_example (mma7361)
 add_example (bh1750)
+add_example (urm37)
+add_example (urm37-uart)

examples/c/urm37-uart.c

@@ -0,0 +1,75 @@
+/*
+ * Author: Jon Trulson <jtrulson@ics.com>
+ * Copyright (c) 2016 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 <signal.h>
+
+#include "urm37.h"
+
+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
+  urm37_context sensor = urm37_init(0, 2, 0, 0, 0, false);
+
+  if (!sensor)
+    {
+      printf("urm37_init() failed.\n");
+      return(1);
+    }
+
+  // Every half a second, sample the URM37 and output the measured
+  // distance in cm.
+
+  while (shouldRun)
+    {
+      float distance, temperature;
+
+      urm37_get_distance(sensor, &distance, 0);
+      printf("Detected distance (cm): %f\n", distance);
+
+      urm37_get_temperature(sensor, &temperature);
+      printf("Temperature (C): %f\n\n", temperature);
+      usleep(500000);
+    }
+
+//! [Interesting]
+
+  printf("Exiting\n");
+
+  urm37_close(sensor);
+
+  return 0;
+}

examples/c/urm37.c

@@ -0,0 +1,73 @@
+/*
+ * Author: Jon Trulson <jtrulson@ics.com>
+ * Copyright (c) 2016 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 <signal.h>
+
+#include "urm37.h"
+
+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
+  urm37_context sensor = urm37_init(0, 2, 3, 5.0, 0, true);
+
+  if (!sensor)
+    {
+      printf("urm37_init() failed.\n");
+      return(1);
+    }
+
+  // Every half a second, sample the URM37 and output the measured
+  // distance in cm.
+
+  while (shouldRun)
+    {
+      float distance;
+
+      urm37_get_distance(sensor, &distance, 0);
+      printf("Detected distance (cm): %f\n", distance);
+      usleep(500000);
+    }
+
+//! [Interesting]
+
+  printf("Exiting\n");
+
+  urm37_close(sensor);
+
+  return 0;
+}

src/urm37/CMakeLists.txt

@@ -1,5 +1,9 @@
-set (libname "urm37")
+upm_mixed_module_init (NAME urm37
-set (libdescription "upm DFRobot URM37 Ultrasonic ranger")
+    DESCRIPTION "upm URM37 Ultrasonic Ranger"
-set (module_src ${libname}.cxx)
+    C_HDR urm37.h
-set (module_hpp ${libname}.hpp)
+    C_SRC urm37.c
-upm_module_init()
+    CPP_HDR urm37.hpp
+    CPP_SRC urm37.cxx
+    FTI_SRC urm37_fti.c
+    CPP_WRAPS_C
+    REQUIRES upmc-utilities mraa)

src/urm37/urm37.c

@@ -0,0 +1,386 @@
+/*
+ * Author: Jon Trulson <jtrulson@ics.com>
+ *         Abhishek Malik <abhishek.malik@intel.com>
+ * Copyright (c) 2016 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.
+ */
+
+#include <string.h>
+
+#include "urm37.h"
+
+#include "upm_utilities.h"
+
+#define URM37_MAX_DATA_LEN      4
+#define URM37_WAIT_TIMEOUT      1000
+#define URM37_MAX_RETRIES       10
+
+urm37_context urm37_init(uint8_t a_pin, uint8_t reset_pin,
+                         uint8_t trigger_pin, float a_ref,
+                         uint8_t uart_bus, bool analog_mode)
+{
+
+  urm37_context dev = (urm37_context)malloc(sizeof(struct _urm37_context));
+
+  if (!dev)
+    return NULL;
+
+  // clear out context
+  memset((void *)dev, 0, sizeof(struct _urm37_context));
+  
+  // NULL out MRAA contexts for now (redundant with memset I know, but...)
+  dev->aio = NULL;
+  dev->gpio_reset = NULL;
+  dev->gpio_trigger = NULL;
+  dev->uart = NULL;
+
+  dev->a_res = 0;
+  dev->a_ref = a_ref;
+
+  // set the mode
+  dev->is_analog_mode = analog_mode;
+
+  // initialize the MRAA contexts (only what we need)
+
+  // analog only
+  if (dev->is_analog_mode)
+    {
+      if (!(dev->aio = mraa_aio_init(a_pin)))
+        {
+          printf("%s: mraa_aio_init() failed.\n", __FUNCTION__);
+          urm37_close(dev);
+          return NULL;
+        }
+
+      // ADC resolution
+      dev->a_res = (float)(1 << mraa_aio_get_bit(dev->aio)) - 1;
+
+      if (!(dev->gpio_trigger = mraa_gpio_init(trigger_pin)))
+        {
+          printf("%s: mraa_gpio_init(trigger) failed.\n", __FUNCTION__);
+          urm37_close(dev);
+          return NULL;
+        }
+
+      mraa_gpio_dir(dev->gpio_trigger, MRAA_GPIO_OUT);
+      mraa_gpio_write(dev->gpio_trigger, 1);
+    }
+  else
+    {
+      // UART only
+      if (!(dev->uart = mraa_uart_init(uart_bus)))
+        {
+          printf("%s: mraa_uart_init() failed.\n", __FUNCTION__);
+          urm37_close(dev);
+          return NULL;
+        }
+
+      mraa_uart_set_baudrate(dev->uart, 9600);
+      mraa_uart_set_non_blocking(dev->uart, false);
+    }
+
+  // reset - used by both analog and uart modes
+  if (!(dev->gpio_reset = mraa_gpio_init(reset_pin)))
+    {
+      printf("%s: mraa_gpio_init(reset) failed.\n", __FUNCTION__);
+      urm37_close(dev);
+      return NULL;
+    }
+
+  mraa_gpio_dir(dev->gpio_reset, MRAA_GPIO_OUT);
+
+  urm37_reset(dev);
+
+  return dev;
+}
+
+void urm37_close(urm37_context dev)
+{
+  if (dev->aio)
+    mraa_aio_close(dev->aio);
+  if (dev->gpio_reset)
+    mraa_gpio_close(dev->gpio_reset);
+  if (dev->gpio_trigger)
+    mraa_gpio_close(dev->gpio_trigger);
+  if (dev->uart)
+    mraa_uart_stop(dev->uart);
+
+  free(dev);
+}
+
+upm_result_t urm37_reset(urm37_context dev)
+{
+  mraa_gpio_write(dev->gpio_reset, 0);
+  upm_delay_us(100);
+  mraa_gpio_write(dev->gpio_reset, 1);
+
+  // wait for reset to complete
+  upm_delay(3);
+
+  return UPM_SUCCESS;
+}
+
+// private
+static bool urm37_data_available(urm37_context dev, uint32_t millis)
+{
+  if (mraa_uart_data_available(dev->uart, millis))
+    return true;
+  else
+    return false;
+}
+
+// private
+static int urm37_read_data(urm37_context dev, char* data)
+{
+  return mraa_uart_read(dev->uart, data, (size_t)URM37_MAX_DATA_LEN);
+}
+
+// private
+static int urm37_write_data(urm37_context dev, const char* data)
+{
+  mraa_uart_flush(dev->uart);
+  return mraa_uart_write(dev->uart, data, (size_t)URM37_MAX_DATA_LEN);
+}
+
+upm_result_t urm37_send_command(urm37_context dev, char* cmd, char* response)
+{
+  if (dev->is_analog_mode)
+    {
+      printf("%s: UART commands are not available in analog mode\n",
+             __FUNCTION__);
+      
+      return UPM_ERROR_NOT_SUPPORTED;
+    }
+
+  int tries = 0;
+
+  while (tries++ < URM37_MAX_RETRIES)
+    {
+      if (urm37_write_data(dev, cmd) < 0)
+        {
+          // A write error of some kind.  We don't try to continue
+          // after this.
+          printf("%s: write_data() failed\n", __FUNCTION__);
+
+          return UPM_ERROR_OPERATION_FAILED;
+        }
+
+      if (!urm37_data_available(dev, URM37_WAIT_TIMEOUT))
+        {
+          // timeout, retry...
+          continue;
+        }
+
+      int rv = urm37_read_data(dev, response);
+      if (rv < 0)
+        {
+          printf("%s: read_data() failed\n", __FUNCTION__);
+          return UPM_ERROR_OPERATION_FAILED;
+        }
+
+      if (rv != URM37_MAX_DATA_LEN)
+        {
+          // read wrong number of bytes...
+          printf("%s: read_data() returned %d bytes, expected %d, retrying\n",
+                 __FUNCTION__, rv, URM37_MAX_DATA_LEN);
+          continue;
+        }
+      else
+        {
+          // we have data, verify cksum, return the response if it's
+          // good, retry otherwise
+          uint8_t cksum = (uint8_t)(response[0] + response[1] + response[2]);
+
+          if ((uint8_t)response[3] != cksum)
+            {
+              printf("%s: checksum failure: got %d, expected %d, retrying\n",
+                     __FUNCTION__, (int)response[3], (int)cksum);
+              continue;
+            }
+
+          // all good
+          return UPM_SUCCESS;
+        }
+    }
+
+  // If we are here, we timed out and all retries were exhausted
+  return UPM_ERROR_TIMED_OUT;
+}
+
+upm_result_t urm37_get_distance(urm37_context dev, float *distance,
+                                int degrees)
+{
+  if (dev->is_analog_mode)
+    {
+      // analog mode
+      int val;
+
+      // send the trigger pulse and sample
+      mraa_gpio_write(dev->gpio_trigger, 0);
+      val = mraa_aio_read(dev->aio);
+      mraa_gpio_write(dev->gpio_trigger, 1);
+
+      // convert to mV
+      float volts = ((float)val * (dev->a_ref / dev->a_res)) * 1000.0;
+
+      // 6.8 mV/cm
+      *distance = volts/6.8;
+      return UPM_SUCCESS;
+    }
+
+  // UART mode
+
+  char cmd[URM37_MAX_DATA_LEN];
+  char resp[URM37_MAX_DATA_LEN];
+
+  // divide degrees by 6 - this is the encoding URM37 uses.
+  uint8_t deg = (uint8_t)(degrees / 6);
+  if (deg > 46)
+    {
+      printf("%s: Degrees out of range, must be between 0-270\n",
+             __FUNCTION__);
+      return UPM_ERROR_OUT_OF_RANGE;
+    }
+
+  uint8_t cksum = 0x22 + deg + 0x00;
+  cmd[0] = 0x22;
+  cmd[1] = deg;
+  cmd[2] = 0x00;
+  cmd[3] = cksum;
+
+  if (urm37_send_command(dev, cmd, resp) != UPM_SUCCESS)
+    {
+      printf("%s: urm37_send_command() failed\n", __FUNCTION__);
+      return UPM_ERROR_OPERATION_FAILED;
+    }
+
+  uint8_t h = (uint8_t) resp[1];
+  uint8_t l = (uint8_t) resp[2];
+
+  *distance = (float)((h << 8) | l);
+
+  return UPM_SUCCESS;
+}
+
+upm_result_t urm37_get_temperature(urm37_context dev, float* temperature)
+{
+  if (dev->is_analog_mode)
+    {
+      printf("%s: Temperature measurement is not available in analog mode\n",
+             __FUNCTION__);
+      return UPM_ERROR_NOT_SUPPORTED;
+    }
+
+  // UART mode
+  char cmd[URM37_MAX_DATA_LEN];
+
+  // get temperature sequence
+  cmd[0] = 0x11;
+  cmd[1] = 0x00;
+  cmd[2] = 0x00;
+  cmd[3] = 0x11; // cksum
+
+  char resp[URM37_MAX_DATA_LEN];
+  if (urm37_send_command(dev, cmd, resp) != UPM_SUCCESS)
+    {
+      printf("%s: urm37_send_command() failed\n", __FUNCTION__);
+      return UPM_ERROR_OPERATION_FAILED;
+    }
+
+  uint8_t h = (uint8_t) resp[1];
+  uint8_t l = (uint8_t) resp[2];
+
+  *temperature = (float)((h & 0x0f) * 256 + l) / 10.0;
+
+  if (h & 0xf0)
+    *temperature *= -1;
+
+  return UPM_SUCCESS;
+}
+
+upm_result_t urm37_read_eeprom(urm37_context dev, uint8_t addr, uint8_t* value)
+{
+  if (dev->is_analog_mode)
+    {
+      printf("%s: EEPROM is not available in analog mode\n",
+             __FUNCTION__);
+      return UPM_ERROR_NOT_SUPPORTED;
+    }
+
+  if (addr > 0x04)
+    {
+      printf("Address must be between 0x00-0x04");
+      return UPM_ERROR_OUT_OF_RANGE;
+    }
+
+  char cmd[URM37_MAX_DATA_LEN];
+  uint8_t cksum = 0x33 + addr + 0x00;
+  cmd[0] = 0x33;
+  cmd[1] = addr;
+  cmd[2] = 0x00;
+  cmd[3] = cksum;
+
+  char resp[URM37_MAX_DATA_LEN];
+
+  if (urm37_send_command(dev, cmd, resp) != UPM_SUCCESS)
+    {
+      printf("%s: urm37_send_command() failed\n", __FUNCTION__);
+      return UPM_ERROR_OPERATION_FAILED;
+    }
+
+  *value = resp[2];
+  return UPM_SUCCESS;
+}
+
+upm_result_t urm37_write_eeprom(urm37_context dev, uint8_t addr, uint8_t value)
+{
+  if (dev->is_analog_mode)
+    {
+      printf("%s: EEPROM is not available in analog mode\n",
+             __FUNCTION__);
+      return UPM_ERROR_NOT_SUPPORTED;
+    }
+
+  if (addr > 0x04)
+    {
+      printf("Address must be between 0x00-0x04");
+      return UPM_ERROR_OUT_OF_RANGE;
+    }
+
+  char cmd[URM37_MAX_DATA_LEN];
+  uint8_t cksum = 0x44 + addr + value;
+  cmd[0] = 0x44;
+  cmd[1] = addr;
+  cmd[2] = value;
+  cmd[3] = cksum;
+
+  char resp[URM37_MAX_DATA_LEN]; // throw away
+  if (urm37_send_command(dev, cmd, resp) != UPM_SUCCESS)
+    {
+      printf("%s: urm37_send_command() failed\n", __FUNCTION__);
+      return UPM_ERROR_OPERATION_FAILED;
+    }
+
+  return UPM_SUCCESS;
+}

src/urm37/urm37.cxx

@@ -23,296 +23,76 @@
  */
 
 #include <iostream>
+#include <stdexcept>
 
 #include "urm37.hpp"
 
 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_urm37(urm37_init(aPin, resetPin, triggerPin, aref, 0, true))
-  m_gpioTrigger(new mraa::Gpio(triggerPin))
 {
-  m_analogMode = true;
+  if (!m_urm37)
-
+    throw std::runtime_error(string(__FUNCTION__) +
-  m_aRes = (1 << m_aio->getBit());
+                             ": urm37_init() failed");
-  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_urm37(urm37_init(0, resetPin, 0, 0, uart, false))
-  m_gpioTrigger(0)
 {
-  m_analogMode = false;
+  if (!m_urm37)
-
+    throw std::runtime_error(string(__FUNCTION__) +
-  m_aRes = 0;
+                             ": urm37_init() failed");
-  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)
+  urm37_close(m_urm37);
-    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
+  urm37_reset(m_urm37);
-  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
+  float distance;
-  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
+  if (urm37_get_distance(m_urm37, &distance, degrees) != UPM_SUCCESS)
-  // query distance cmd sequence
+    throw std::runtime_error(string(__FUNCTION__) +
-  uint8_t deg = (uint8_t)(degrees / 6);
+                             ": urm37_get_distance() failed");
-  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)
+  float temperature;
-    {
-      throw std::runtime_error(string(__FUNCTION__) +
-                 ": Temperature measurement not available in analog mode");
 
-      return 0.0;
+  if (urm37_get_temperature(m_urm37, &temperature) != UPM_SUCCESS)
-    }
+    throw std::runtime_error(string(__FUNCTION__) +
+                             ": urm37_get_temperature() failed");
 
-  // query temperature cmd sequence
+  return temperature;
-  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)
+  uint8_t value;
-    {
-      throw std::runtime_error(string(__FUNCTION__) +
-                 ": readEEPROM() is not possible in analog mode");
 
-      return 0;
+  if (urm37_read_eeprom(m_urm37, addr, &value) != UPM_SUCCESS)
-    }
+    throw std::runtime_error(string(__FUNCTION__) +
+                             ": urm37_read_eeprom() failed");
 
-  if (addr > 0x04)
+  return value;
-    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)
+  if (urm37_write_eeprom(m_urm37, addr, value) != UPM_SUCCESS)
-    {
+    throw std::runtime_error(string(__FUNCTION__) +
-      throw std::runtime_error(string(__FUNCTION__) +
+                             ": urm37_write_eeprom() failed");
-                 ": 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 +1,173 @@
+/*
+ * Author: Jon Trulson <jtrulson@ics.com>
+ *         Abhishek Malik <abhishek.malik@intel.com>
+ * Copyright (c) 2016 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.
+ */
+
+#ifndef URM37_H_
+#define URM37_H_
+
+#include <stdint.h>
+#include "upm.h"
+#include "mraa/aio.h"
+#include "mraa/gpio.h"
+#include "mraa/uart.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief UPM C 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.c Interesting
+ * An example using UART mode
+ * @snippet urm37-uart.c Interesting
+ */
+
+/**
+ * device context
+ */
+typedef struct _urm37_context {
+  mraa_aio_context    aio;
+  mraa_gpio_context   gpio_reset;
+  mraa_gpio_context   gpio_trigger;
+  mraa_uart_context   uart;
+
+  bool                is_analog_mode;
+
+  float               a_ref;
+  float               a_res;
+} *urm37_context;
+
+/**
+ * URM37 Initializer
+ *
+ * @param a_pin Analog pin to use. Ignored in UART mode.
+ * @param reset_pin GPIO pin to use for reset
+ * @param trigger_pin GPIO pin to use for triggering a distance
+ * measurement. Ignored in UART mode.
+ * @param a_ref The analog reference voltage. Ignored in UART mode.
+ * @param uart Default UART to use (0 or 1). Ignored in analog mode.
+ * @param mode true for analog mode, false otherwise.
+ */
+urm37_context urm37_init(uint8_t a_pin, uint8_t reset_pin,
+                         uint8_t trigger_pin, float a_ref, 
+                         uint8_t uart, bool analog_mode);
+
+/**
+ * URM37 sensor close function
+ */
+void urm37_close(urm37_context dev);
+
+/**
+ * Reset the device.  This will take approximately 3 seconds to
+ * complete.
+ *
+ * @param dev sensor context
+ */
+upm_result_t urm37_reset(urm37_context dev);
+
+/**
+ * Get the distance measurement.  A return value of 65535.0
+ * in UART mode indicates an invalid measurement.
+ *
+ * @param dev sensor context
+ * @param distance A pointer to a float that will contain the distance
+ * in CM if the measurement is successful.
+ * @param degrees In UART mode, this specifies the degrees to turn an
+ * attached PWM servo connected to the MOTO output on the URM37.
+ * Valid values are 0-270.  This option is ignored in analog mode.  If
+ * you are not using this functionality, just pass 0.
+ * @return UPM status code
+ */
+upm_result_t urm37_get_distance(urm37_context dev, float *distance,
+                                int degrees);
+
+/**
+ * Get the temperature measurement.  This is only valid in UART mode.
+ *
+ * @param dev sensor context
+ * @param temperature A float pointer containing the measured
+ * temperature in degrees C
+ * @return UPM status code
+ *
+ */
+upm_result_t urm37_get_temperature(urm37_context dev, float* temperature);
+
+/**
+ * In UART mode only, read a value from the EEPROM and return it.
+ *
+ * @param dev sensor context
+ * @param addr The address in the EEPROM to read.  Valid values
+ * are between 0x00-0x04.
+ * @param value A pointer containing the returned value.
+ * @return UPM status code
+ */
+upm_result_t urm37_read_eeprom(urm37_context dev, uint8_t addr, uint8_t* value);
+
+/**
+ * In UART mode only, write a value into an address on the EEPROM.
+ *
+ * @param dev sensor context
+ * @param addr The address in the EEPROM to write.  Valid values
+ * are between 0x00-0x04.
+ * @param value The value to write
+ * @return UPM status code
+ */
+upm_result_t urm37_write_eeprom(urm37_context dev, uint8_t addr, uint8_t value);
+
+/**
+ * In UART mode only, send a 4-byte command, and return a 4-byte response.
+ *
+ * @param dev sensor context
+ * @param cmd A 4-byte command to transmit
+ * @param response The 4-byte response
+ * @return UPM response code (success, failure, or timeout)
+ */
+upm_result_t urm37_send_command(urm37_context dev, char* cmd, char* response);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* URM37_H_ */

src/urm37/urm37.hpp

@@ -1,6 +1,6 @@
 /*
  * Author: Jon Trulson <jtrulson@ics.com>
- * Copyright (c) 2015 Intel Corporation.
+ * Copyright (c) 2015-2016 Intel Corporation.
  *
  * Thanks to Adafruit for supplying a google translated version of the
  * Chinese datasheet and some clues in their code.
@@ -33,12 +33,7 @@
 #include <unistd.h>
 #include <string.h>
 
-#include <mraa/common.hpp>
+#include "urm37.h"
-#include <mraa/uart.hpp>
-#include <mraa/aio.hpp>
-#include <mraa/gpio.hpp>
-
-#define URM37_DEFAULT_UART 0
 
 namespace upm {
     /**
@@ -153,52 +148,10 @@ namespace upm {
     void writeEEPROM(uint8_t addr, uint8_t value);
 
   protected:
-    mraa::Uart *m_uart;
+    // urm37 device context
-    mraa::Aio *m_aio;
+    urm37_context m_urm37;
-    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;
   };
 }
 

src/urm37/urm37_fti.c

@@ -0,0 +1,109 @@
+/*
+ * Author: Jon Trulson <jtrulson@ics.com>
+ *         Abhishek Malik <abhishek.malik@intel.com>
+ * Copyright (c) 2016 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.
+ */
+
+#include "urm37.h"
+#include "upm_fti.h"
+
+/** 
+ * This file implements the Function Table Interface (FTI) for this sensor
+ */
+
+const char upm_light_name[] = "URM37";
+const char upm_light_description[] = "Ultrasonic Ranger";
+// problem here is it's an either/or analog vs. uart.  So we will just
+// only support analog for now
+// 1st gpio is reset, 2nd is trigger
+const upm_protocol_t upm_light_protocol[] = {UPM_ANALOG, UPM_GPIO, UPM_GPIO};
+const upm_sensor_t upm_light_category[] = {UPM_DISTANCE};
+
+// forward declarations
+const void* upm_urm37_get_ft(upm_sensor_t sensor_type);
+void* upm_urm37_init_name();
+void upm_urm37_close(void* dev);
+upm_result_t upm_urm37_get_distance(void* dev, float* distance,
+                                    upm_distance_u unit);
+
+static const upm_sensor_ft ft =
+{
+    .upm_sensor_init_name = &upm_urm37_init_name,
+    .upm_sensor_close = &upm_urm37_close,
+};
+
+static const upm_distance_ft dft =
+{
+    .upm_distance_get_value = &upm_urm37_get_distance
+};
+
+const void* upm_urm37_get_ft(upm_sensor_t sensor_type)
+{
+  switch(sensor_type)
+    {
+    case UPM_SENSOR:
+      return &ft;
+      
+    case UPM_DISTANCE:
+      return &dft;
+      
+    default:
+      return NULL;
+    }
+}
+
+void* upm_urm37_init_name()
+{
+    return NULL;
+}
+
+
+void upm_urm37_close(void* dev)
+{
+    urm37_close((urm37_context)dev);
+}
+
+upm_result_t upm_urm37_get_distance(void* dev, float* distance,
+                                    upm_distance_u unit)
+{
+  // only cm returned by sensor
+  float dist;
+  urm37_get_distance((urm37_context)dev, &dist, 0);
+
+  switch(unit)
+    {
+    case CENTIMETER:
+      *distance = dist;
+      return UPM_SUCCESS;
+
+    case INCH:
+      *distance = dist / 2.54;
+      return UPM_SUCCESS;
+
+    default:
+      return UPM_ERROR_INVALID_PARAMETER;
+    }
+}
+