diff --git a/DOC/dbase/lg.sqlite b/DOC/dbase/lg.sqlite
index ffbdf7b..fd05e93 100644
Binary files a/DOC/dbase/lg.sqlite and b/DOC/dbase/lg.sqlite differ
diff --git a/DOC/src/defs/examples.def b/DOC/src/defs/examples.def
index 6567d1f..2e639ac 100644
--- a/DOC/src/defs/examples.def
+++ b/DOC/src/defs/examples.def
@@ -58,6 +58,17 @@ E.g.
 
 ./rotary_encoder 2 7 5 # gpiochip 2, gpioA 7, gpioB 5
 
+?4|sonar_ranger.c|2020-11-20|Sonar Ranger
+Code to find the distance between a sonar ranger and the nearest object.  The code assumes the sonar ranger is the type with separate trigger and echo lines.
+
+./sonar_ranger [chip] trigger echo
+
+E.g.
+
+./sonar_ranger 20 21 # gpiochip 0, trigger 20, echo 21
+
+./sonar_ranger 2 7 5 # gpiochip 2, trigger 7, echo 5
+
 ?4|tx_pulse.c|2020-11-18|Tx Pulse
 Demonstrates usage of the tx pulse function.
 
@@ -107,6 +118,17 @@ E.g.
 
 ./rotary_encoder.py 2 7 5 # gpiochip 2, gpioA 7, gpioB 5
 
+?4|sonar_ranger.py|2020-11-20|Sonar Ranger
+Code to find the distance between a sonar ranger and the nearest object.  The code assumes the sonar ranger is the type with separate trigger and echo lines.
+
+./sonar_ranger.py [chip] trigger echo
+
+E.g.
+
+./sonar_ranger.py 20 21 # gpiochip 0, trigger 20, echo 21
+
+./sonar_ranger.py 2 7 5 # gpiochip 2, trigger 7, echo 5
+
 ?4|testbed.py|2020-11-18|Testbed
 Exercises SPI, I2C, and serial links with miscellaneous hardware.
 
@@ -171,6 +193,16 @@ E.g.
 
 ./rotary_encoder 2 7 5 # gpiochip 2, gpioA 7, gpioB 5
 
+?4|sonar_ranger.c|2020-11-20|Sonar Ranger
+Code to find the distance between a sonar ranger and the nearest object.  The code assumes the sonar ranger is the type with separate trigger and echo lines.
+
+./sonar_ranger [chip] trigger echo
+
+E.g.
+
+./sonar_ranger 20 21 # gpiochip 0, trigger 20, echo 21
+
+./sonar_ranger 2 7 5 # gpiochip 2, trigger 7, echo 5
 
 ?4|tx_pulse.c|2020-11-18|Tx Pulse
 Demonstrates usage of the tx pulse function.
@@ -231,6 +263,17 @@ E.g.
 
 ./rotary_encoder.py 2 7 5 # gpiochip 2, gpioA 7, gpioB 5
 
+?4|sonar_ranger.py|2020-11-20|Sonar Ranger
+Code to find the distance between a sonar ranger and the nearest object.  The code assumes the sonar ranger is the type with separate trigger and echo lines.
+
+./sonar_ranger.py [chip] trigger echo
+
+E.g.
+
+./sonar_ranger.py 20 21 # gpiochip 0, trigger 20, echo 21
+
+./sonar_ranger.py 2 7 5 # gpiochip 2, trigger 7, echo 5
+
 ?4|testbed.py|2020-11-18|Testbed
 Exercises SPI, I2C, and serial links with miscellaneous hardware.
 
diff --git a/EXAMPLES/lgpio/chipline.c b/EXAMPLES/lgpio/chipline.c
index 120d8f0..94e8be4 100644
--- a/EXAMPLES/lgpio/chipline.c
+++ b/EXAMPLES/lgpio/chipline.c
@@ -1,13 +1,13 @@
 /*
-bench.c
+chipline.c
 2020-11-18
 Public Domain
 
 http://abyz.me.uk/lg/lgpio.html
 
-gcc -Wall -o bench bench.c -llgpio
+gcc -Wall -o chipline chipline.c -llgpio
 
-./bench
+./chipline
 */
 #include <stdio.h>
 
diff --git a/EXAMPLES/lgpio/sonar_ranger.c b/EXAMPLES/lgpio/sonar_ranger.c
new file mode 100644
index 0000000..eb7110e
--- /dev/null
+++ b/EXAMPLES/lgpio/sonar_ranger.c
@@ -0,0 +1,140 @@
+/*
+sonar_ranger.c
+2020-11-20
+Public Domain
+
+http://abyz.me.uk/lg/lgpio.html
+
+gcc -Wall -o sonar_ranger sonar_ranger.c -llgpio
+
+./sonar_ranger [chip] trigger echo
+
+E.g.
+
+./sonar_ranger 20 21 # ping gpiochip 0, trigger 20, echo 21
+
+./sonar_ranger 2 7 5 # gpiochip 2, trigger 7, echo 5
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <lgpio.h>
+
+int pinged = 0;
+uint64_t ping_time;
+
+void cbf(int e, lgGpioAlert_p evt, void *userdata)
+{
+   int i;
+   static uint64_t _high = 0;
+
+   for (i=0; i<e; i++)
+   {
+      if (evt[i].report.level == 1) _high = evt[i].report.timestamp;
+      else
+      {
+         if (_high != 0)
+         {
+            ping_time = evt[i].report.timestamp - _high;
+            _high = 0;
+            pinged = 1;
+         }
+      }
+   }
+}
+
+float readRanger(int h, int trigger)
+{
+   double start;
+
+   /*
+      Return the distance in cms if okay, otherwise 0.
+   */
+
+   pinged = 0;
+
+   /* send a 15 microsecond high pulse as trigger */
+   lgTxPulse(h, trigger, 15, 0, 0, 1);
+
+   start = lguTime();
+
+   while (!pinged)
+   {
+      if ((lguTime() - start) > 0.3) return 0.0;
+      lguSleep(0.01);
+   }
+
+   return 17015.0 * ping_time / 1e9;
+}
+
+int main(int argc, char *argv[])
+{
+   int h;
+   int chip, trigger, echo;
+   int cb_echo;
+   int err;
+
+   if (argc == 4) /* chip trigger echo */
+   {
+      chip = atoi(argv[1]);
+      trigger = atoi(argv[2]);
+      echo = atoi(argv[3]);
+   }
+
+   else if (argc == 3) /* trigger echo (chip 0) */
+   {
+      chip = 0;
+      trigger = atoi(argv[1]);
+      echo = atoi(argv[2]);
+   }
+
+   else
+   {
+      fprintf(stderr, "Usage: ./sonar_ranger [chip] trigger echo\n");
+      return -1;
+   }
+
+   h = lgGpiochipOpen(chip);
+
+   if (h < 0)
+   {
+      fprintf(stderr, "can't open /dev/gpiochip%d (%s)\n",
+         chip, lgErrStr(h));
+      return -1;
+   }
+
+   err = lgGpioClaimOutput(h, 0, trigger, 0);
+
+   if (err < 0)
+   {
+      fprintf(stderr, "can't claim GPIO %d (%s)\n",
+         trigger, lgErrStr(err));
+      return -1;
+   }
+
+   err = lgGpioClaimAlert(h, 0, LG_BOTH_EDGES, echo, -1);
+
+   if (err < 0)
+   {
+      fprintf(stderr, "can't claim GPIO %d (%s)\n",
+         echo, lgErrStr(err));
+      return -1;
+   }
+
+   err = lgGpioSetAlertsFunc(h, echo, cbf, NULL);
+
+   if (err < 0)
+   {
+      fprintf(stderr, "can't create callback for GPIO %d (%s)\n",
+         echo, lgErrStr(cb_echo));
+      return -1;
+   }
+
+   while (1)
+   {
+      printf("cms=%.1f\n", readRanger(h, trigger));
+      lguSleep(0.2);
+   }
+}
+
diff --git a/EXAMPLES/py_lgpio/sonar_ranger.py b/EXAMPLES/py_lgpio/sonar_ranger.py
new file mode 100644
index 0000000..a78d3c0
--- /dev/null
+++ b/EXAMPLES/py_lgpio/sonar_ranger.py
@@ -0,0 +1,127 @@
+#!/usr/bin/env python
+"""
+sonar_ranger.py
+2020-11-20
+Public Domain
+
+http://abyz.me.uk/lg/py_rgpio.html
+
+./sonar_ranger.py [chip] trigger echo
+
+chip specifies a gpiochip number.  gpio is a GPIO in the previous
+gpiochip (gpiochip0 if there is no previous gpiochip).
+
+e.g.
+
+./sonar_ranger.py 1 24 25 # ping gpiochip1: trigger 24, echo 25
+./sonar_ranger.py 24 25   # ping gpiochip0: trigger 24, echo 25
+"""
+
+import time
+import lgpio
+
+class ranger:
+   """
+   This class encapsulates a type of acoustic ranger.  In particular
+   the type of ranger with separate trigger and echo pins.
+
+   A pulse on the trigger initiates the sonar ping and shortly
+   afterwards a sonar pulse is transmitted and the echo pin
+   goes high.  The echo pins stays high until a sonar echo is
+   received (or the response times-out).  The time between
+   the high and low edges indicates the sonar round trip time.
+   """
+
+   def __init__(self, sbc, chip, trigger, echo):
+      """
+      The class is instantiated with the SBC to use, the gpiochip,
+      and the GPIO connected to the trigger and echo pins.
+      """
+      self._sbc  = sbc
+      self._chip = chip
+      self._trigger = trigger
+      self._echo = echo
+
+      self._ping = False
+      self._high = None
+      self._time = None
+
+      self._handle = sbc.gpiochip_open(chip)
+
+      sbc.gpio_claim_output(self._handle, trigger)
+
+      sbc.gpio_claim_alert(self._handle, echo, sbc.BOTH_EDGES)
+
+      self._cb = sbc.callback(self._handle, echo, sbc.BOTH_EDGES, self._cbf)
+
+      self._inited = True
+
+   def _cbf(self, chip, gpio, level, tick):
+      if level == 1:
+         self._high = tick
+      else:
+         if self._high is not None:
+            self._time = tick - self._high
+            self._high = None
+            self._ping = True
+
+   def read(self):
+      """
+      Return the distance in cms if okay, otherwise 0.
+      """
+      if self._inited:
+         self._ping = False
+         # send a 15 microsecond high pulse as trigger
+         self._sbc.tx_pulse(self._handle, self._trigger, 15, 0, 0, 1)
+         start = time.time()
+         while not self._ping:
+            if (time.time()-start) > 0.3:
+               return 0
+            time.sleep(0.01)
+         return 17015 * self._time / 1e9
+      else:
+         return None
+
+   def cancel(self):
+      """
+      Cancels the ranger and returns the gpios to their
+      original mode.
+      """
+      if self._inited:
+         self._inited = False
+         self._cb.cancel()
+         self._sbc.gpio_free(self._chip, self._trigger)
+         self._sbc.gpio_free(self._chip, self._echo)
+         self._sbc.gpiochip_close(self._chip)
+if __name__ == "__main__":
+
+   import sys
+   import time
+   import lgpio as sbc
+   import sonar_ranger
+
+   if len(sys.argv) == 4: # chip trigger echo
+      chip = int(sys.argv[1])
+      trigger = int(sys.argv[2])
+      echo = int(sys.argv[3])
+
+   elif len(sys.argv) == 3: # trigger echo (chip 0)
+      chip = 0
+      trigger = int(sys.argv[1])
+      echo = int(sys.argv[2])
+
+   else:
+      print("Usage: ./sonar_ranger.py [chip] trigger echo")
+      exit()
+
+   ranger = sonar_ranger.ranger(sbc, chip, trigger, echo)
+
+   try:
+      while True:
+         print("cms={:.1f}".format(ranger.read()))
+         time.sleep(0.2)
+   except KeyboardInterrupt:
+      pass
+
+   ranger.cancel()
+
diff --git a/EXAMPLES/py_rgpio/sonar_ranger.py b/EXAMPLES/py_rgpio/sonar_ranger.py
new file mode 100755
index 0000000..75bada9
--- /dev/null
+++ b/EXAMPLES/py_rgpio/sonar_ranger.py
@@ -0,0 +1,133 @@
+#!/usr/bin/env python
+"""
+sonar_ranger.py
+2020-11-20
+Public Domain
+
+http://abyz.me.uk/lg/py_rgpio.html
+
+./sonar_ranger.py [chip] trigger echo
+
+chip specifies a gpiochip number.  gpio is a GPIO in the previous
+gpiochip (gpiochip0 if there is no previous gpiochip).
+
+e.g.
+
+./sonar_ranger.py 1 24 25 # ping gpiochip1: trigger 24, echo 25
+./sonar_ranger.py 24 25   # ping gpiochip0: trigger 24, echo 25
+"""
+
+import time
+import rgpio
+
+class ranger:
+   """
+   This class encapsulates a type of acoustic ranger.  In particular
+   the type of ranger with separate trigger and echo pins.
+
+   A pulse on the trigger initiates the sonar ping and shortly
+   afterwards a sonar pulse is transmitted and the echo pin
+   goes high.  The echo pins stays high until a sonar echo is
+   received (or the response times-out).  The time between
+   the high and low edges indicates the sonar round trip time.
+   """
+
+   def __init__(self, sbc, chip, trigger, echo):
+      """
+      The class is instantiated with the SBC to use, the gpiochip,
+      and the GPIO connected to the trigger and echo pins.
+      """
+      self._sbc  = sbc
+      self._chip = chip
+      self._trigger = trigger
+      self._echo = echo
+
+      self._ping = False
+      self._high = None
+      self._time = None
+
+      self._handle = sbc.gpiochip_open(chip)
+
+      sbc.gpio_claim_output(self._handle, trigger)
+
+      sbc.gpio_claim_alert(self._handle, echo, rgpio.BOTH_EDGES)
+
+      self._cb = sbc.callback(self._handle, echo, rgpio.BOTH_EDGES, self._cbf)
+
+      self._inited = True
+
+   def _cbf(self, chip, gpio, level, tick):
+      if level == 1:
+         self._high = tick
+      else:
+         if self._high is not None:
+            self._time = tick - self._high
+            self._high = None
+            self._ping = True
+
+   def read(self):
+      """
+      Return the distance in cms if okay, otherwise 0.
+      """
+      if self._inited:
+         self._ping = False
+         # send a 15 microsecond high pulse as trigger
+         self._sbc.tx_pulse(self._handle, self._trigger, 15, 0, 0, 1)
+         start = time.time()
+         while not self._ping:
+            if (time.time()-start) > 0.3:
+               return 0
+            time.sleep(0.01)
+         return 17015 * self._time / 1e9
+      else:
+         return None
+
+   def cancel(self):
+      """
+      Cancels the ranger and returns the gpios to their
+      original mode.
+      """
+      if self._inited:
+         self._inited = False
+         self._cb.cancel()
+         self._sbc.gpio_free(self._chip, self._trigger)
+         self._sbc.gpio_free(self._chip, self._echo)
+         self._sbc.gpiochip_close(self._chip)
+if __name__ == "__main__":
+
+   import sys
+   import time
+   import rgpio
+   import sonar_ranger
+
+   sbc = rgpio.sbc()
+   if not sbc.connected:
+      exit()
+
+   if len(sys.argv) == 4: # chip trigger echo
+      chip = int(sys.argv[1])
+      trigger = int(sys.argv[2])
+      echo = int(sys.argv[3])
+
+   elif len(sys.argv) == 3: # trigger echo (chip 0)
+      chip = 0
+      trigger = int(sys.argv[1])
+      echo = int(sys.argv[2])
+
+   else:
+      print("Usage: ./sonar_ranger.py [chip] trigger echo")
+      exit()
+
+   ranger = sonar_ranger.ranger(sbc, chip, trigger, echo)
+
+   try:
+      while True:
+         print("cms={:.1f}".format(ranger.read()))
+         time.sleep(0.2)
+   except KeyboardInterrupt:
+      pass
+
+   ranger.cancel()
+
+   sbc.stop()
+
diff --git a/EXAMPLES/rgpio/sonar_ranger.c b/EXAMPLES/rgpio/sonar_ranger.c
new file mode 100644
index 0000000..50cb643
--- /dev/null
+++ b/EXAMPLES/rgpio/sonar_ranger.c
@@ -0,0 +1,148 @@
+/*
+sonar_ranger.c
+2020-11-20
+Public Domain
+
+http://abyz.me.uk/lg/rgpio.html
+
+gcc -Wall -o sonar_ranger sonar_ranger.c -lrgpio
+
+./sonar_ranger [chip] trigger echo
+
+E.g.
+
+./sonar_ranger 20 21 # ping gpiochip 0, trigger 20, echo 21
+
+./sonar_ranger 2 7 5 # gpiochip 2, trigger 7, echo 5
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <lgpio.h>
+#include <rgpio.h>
+
+int pinged = 0;
+uint64_t ping_time;
+
+void cbf(
+   int sbc, int chip, int gpio, int level,
+   uint64_t timestamp, void *userdata)
+{
+   static uint64_t _high = 0;
+
+   if (level == 1) _high = timestamp;
+   else
+   {
+      if (_high != 0)
+      {
+         ping_time = timestamp - _high;
+         _high = 0;
+         pinged = 1;
+      }
+   }
+}
+
+float read_ranger(int sbc, int h, int trigger)
+{
+   double start;
+
+   /*
+      Return the distance in cms if okay, otherwise 0.
+   */
+
+   pinged = 0;
+
+   /* send a 15 microsecond high pulse as trigger */
+   tx_pulse(sbc, h, trigger, 15, 0, 0, 1);
+
+   start = lgu_time();
+
+   while (!pinged)
+   {
+      if ((lgu_time() - start) > 0.3) return 0.0;
+      lgu_sleep(0.01);
+   }
+
+   return 17015.0 * ping_time / 1e9;
+}
+
+int main(int argc, char *argv[])
+{
+   int sbc;
+   int h;
+   int chip, trigger, echo;
+   int cb_echo;
+   int err;
+
+   if (argc == 4) /* chip trigger echo */
+   {
+      chip = atoi(argv[1]);
+      trigger = atoi(argv[2]);
+      echo = atoi(argv[3]);
+   }
+
+   else if (argc == 3) /* trigger echo (chip 0) */
+   {
+      chip = 0;
+      trigger = atoi(argv[1]);
+      echo = atoi(argv[2]);
+   }
+
+   else
+   {
+      fprintf(stderr, "Usage: ./sonar_ranger [chip] trigger echo\n");
+      return -1;
+   }
+
+   sbc = rgpiod_start(NULL, NULL);
+
+   if (sbc < 0)
+   {
+      printf("connection failed\n");
+      exit(-1);
+   }
+
+   h = gpiochip_open(sbc, chip);
+
+   if (h < 0)
+   {
+      fprintf(stderr, "can't open /dev/gpiochip%d (%s)\n",
+         chip, lgu_error_text(h));
+      return -1;
+   }
+
+   err = gpio_claim_output(sbc, h, 0, trigger, 0);
+
+   if (err < 0)
+   {
+      fprintf(stderr, "can't claim GPIO %d (%s)\n",
+         trigger, lgu_error_text(err));
+      return -1;
+   }
+
+   err = gpio_claim_alert(sbc, h, 0, LG_BOTH_EDGES, echo, -1);
+
+   if (err < 0)
+   {
+      fprintf(stderr, "can't claim GPIO %d (%s)\n",
+         echo, lgu_error_text(err));
+      return -1;
+   }
+
+   cb_echo = callback(sbc, h, echo, LG_BOTH_EDGES, cbf, NULL);
+
+   if (cb_echo < 0)
+   {
+      fprintf(stderr, "can't create callback for GPIO %d (%s)\n",
+         echo, lgu_error_text(cb_echo));
+      return -1;
+   }
+
+   while (1)
+   {
+      printf("cms=%.1f\n", read_ranger(sbc, h, trigger));
+      lgu_sleep(0.2);
+   }
+}
+
diff --git a/v0.0.4.2 b/v0.0.4.3
similarity index 100%
rename from v0.0.4.2
rename to v0.0.4.3