diff --git a/.gitignore b/.gitignore
index f67291c..98748da 100644
--- a/.gitignore
+++ b/.gitignore
@@ -11,3 +11,5 @@ __pycache__
 build
 dist
 *.egg-info
+wavepad_jitter.py
+
diff --git a/CMakeLists.txt b/CMakeLists.txt
index b36b0d6..383c445 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,14 +1,15 @@
 cmake_minimum_required(VERSION 3.0)
 
-project(pigpio)
+project(pigpio LANGUAGES C VERSION 0.71)
 
-set(CMAKE_C_FLAGS "-O3 -Wall -pthread")
-set(PIGPIO_FLAGS "-L. -lrt")
-#set(DESTDIR ${CMAKE_CURRENT_SOURCE_DIR}/build/dest)
+list (APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_LIST_DIR}/cmake)
 
-if(NOT DEFINED BUILD_SHARED_LIBS)
-set(BUILD_SHARED_LIBS "ON")
-endif(NOT DEFINED BUILD_SHARED_LIBS)
+find_package(Threads REQUIRED)
+find_package(RT REQUIRED)
+
+option(BUILD_SHARED_LIBS "Create shared libraries" ON)
+
+add_compile_options(-Wall)
 
 # libpigpio.(so|a)
 add_library(pigpio pigpio.c command.c custom.cext)
@@ -19,62 +20,76 @@ add_library(pigpiod_if pigpiod_if.c command.c)
 # libpigpiod_if2.(so|a)
 add_library(pigpiod_if2 pigpiod_if2.c command.c)
 
-
 # x_pigpio
 add_executable(x_pigpio x_pigpio.c)
-add_dependencies(x_pigpio pigpio)
-target_link_libraries(x_pigpio
-	${PIGPIO_FLAGS}
-	-lpigpio
-)
+target_link_libraries(x_pigpio pigpio RT::RT Threads::Threads)
 
 # x_pigpiod_if
 add_executable(x_pigpiod_if x_pigpiod_if.c)
-add_dependencies(x_pigpiod_if pigpiod_if)
-target_link_libraries(x_pigpiod_if
-	${PIGPIO_FLAGS}
-	-lpigpiod_if
-)
+target_link_libraries(x_pigpiod_if pigpiod_if RT::RT Threads::Threads)
 
 # x_pigpiod_if2
 add_executable(x_pigpiod_if2 x_pigpiod_if2.c)
-add_dependencies(x_pigpiod_if2 pigpiod_if2)
-target_link_libraries(x_pigpiod_if2
-	${PIGPIO_FLAGS}
-	-lpigpiod_if2
-)
+target_link_libraries(x_pigpiod_if2 pigpiod_if2 RT::RT Threads::Threads)
 
 # pigpiod
 add_executable(pigpiod pigpiod.c)
-add_dependencies(pigpiod pigpio)
-target_link_libraries(pigpiod
-	${PIGPIO_FLAGS}
-	-lpigpio
-)
+target_link_libraries(pigpiod pigpio RT::RT Threads::Threads)
 
 # pigs
 add_executable(pigs pigs.c command.c)
+target_link_libraries(pigs Threads::Threads)
 
 # pig2vcd
 add_executable(pig2vcd pig2vcd.c command.c)
+target_link_libraries(pig2vcd Threads::Threads)
 
-# install
-install(DIRECTORY
-	DESTINATION ${DESTDIR}/opt/pigpio/cgi
-	PATTERN ""
-	PERMISSIONS OWNER_EXECUTE OWNER_WRITE OWNER_READ
-		GROUP_READ GROUP_EXECUTE
-		WORLD_READ WORLD_EXECUTE
-)
+# Configure and install project
+
+include (GenerateExportHeader)
+include (CMakePackageConfigHelpers)
+
+generate_export_header(${PROJECT_NAME})
 
 install(TARGETS pigpio pigpiod_if pigpiod_if2 pig2vcd pigpiod pigs
-	LIBRARY DESTINATION ${DESTDIR}/usr/local/lib
-	RUNTIME DESTINATION ${DESTDIR}/usr/local/bin
-	ARCHIVE DESTINATION ${DESTDIR}/usr/local/lib
+    EXPORT ${PROJECT_NAME}Targets
+	LIBRARY  DESTINATION lib
+	ARCHIVE  DESTINATION lib
+	RUNTIME  DESTINATION bin
+	INCLUDES DESTINATION include
+)
+
+write_basic_package_version_file(
+	"${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}ConfigVersion.cmake"
+	VERSION ${${PROJECT_NAME}_VERSION}
+	COMPATIBILITY AnyNewerVersion
+)
+
+export(EXPORT ${PROJECT_NAME}Targets
+  FILE "${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}Targets.cmake"
+  NAMESPACE pigpio::
+)
+
+set(ConfigPackageLocation lib/cmake/${PROJECT_NAME})
+install(EXPORT ${PROJECT_NAME}Targets
+  FILE
+    ${PROJECT_NAME}Targets.cmake
+  NAMESPACE
+    pigpio::
+  DESTINATION
+    ${ConfigPackageLocation}
+)
+
+install(
+  FILES
+    ${CMAKE_CURRENT_LIST_DIR}/cmake/${PROJECT_NAME}Config.cmake
+    "${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}ConfigVersion.cmake"
+  DESTINATION
+    ${ConfigPackageLocation}
 )
 
 install(FILES pigpio.h pigpiod_if.h pigpiod_if2.h
-	DESTINATION ${DESTDIR}/usr/local/include
+	DESTINATION include
 	PERMISSIONS OWNER_READ OWNER_WRITE
 		GROUP_READ
 		WORLD_READ
@@ -82,7 +97,7 @@ install(FILES pigpio.h pigpiod_if.h pigpiod_if2.h
 
 file(GLOB man_1_SRC "*.1")
 install(FILES ${man_1_SRC}
-	DESTINATION ${DESTDIR}/usr/local/man/man1
+	DESTINATION man/man1
 	PERMISSIONS OWNER_READ OWNER_WRITE
 		GROUP_READ
 		WORLD_READ
@@ -90,48 +105,23 @@ install(FILES ${man_1_SRC}
 
 file(GLOB man_3_SRC "*.3")
 install(FILES ${man_3_SRC}
-	DESTINATION ${DESTDIR}/usr/local/man/man3
+	DESTINATION man/man3
 	PERMISSIONS OWNER_READ OWNER_WRITE
 		GROUP_READ
 		WORLD_READ
 )
 
-file(GLOB setup_SRC "setup.py")
-find_program(PYTHON2_FOUND python2)
-if(PYTHON2_FOUND)
-	install(CODE "execute_process(COMMAND cd ${CMAKE_SOURCE_DIR} && python2 ${setup_SRC} install)")
-endif()
-find_program(PYTHON3_FOUND python3)
-if(PYTHON3_FOUND)
-	install(CODE "execute_process(COMMAND cd ${CMAKE_SOURCE_DIR} && python3 ${setup_SRC} install)")
+# Install python modules.
+find_package(Python COMPONENTS Interpreter QUIET)
+
+if(Python_FOUND)
+	configure_file(${CMAKE_CURRENT_LIST_DIR}/cmake/setup.py.in
+		${CMAKE_CURRENT_BINARY_DIR}/setup.py
+	)
+
+	install(CODE "execute_process(COMMAND ${Python_EXECUTABLE} ${CMAKE_CURRENT_BINARY_DIR}/setup.py install)")
 endif()
 
-install(CODE "execute_process(COMMAND ldconfig)")
+# package project
 
-# uninstall
-if(PYTHON2_FOUND)
-	set(PY2_CMD python2 ${setup_SRC} install --record /tmp/pigpio > /dev/null)
-	set(PY2_CMD ${PY2_CMD} && xargs rm -f < /tmp/pigpio > /dev/null)
-endif()
-
-if(PYTHON3_FOUND)
-	set(PY3_CMD python3 ${setup_SRC} install --record /tmp/pigpio > /dev/null)
-	set(PY3_CMD ${PY3_CMD} && xargs rm -f < /tmp/pigpio > /dev/null)
-endif()
-
-add_custom_target(uninstall
-	COMMAND rm -f ${DESTDIR}/usr/local/include/pigpio.h
-	COMMAND rm -f ${DESTDIR}/usr/local/include/pigpiod_if.h
-	COMMAND rm -f ${DESTDIR}/usr/local/include/pigpiod_if2.h
-	COMMAND rm -f ${DESTDIR}/usr/local/lib/libpigpio.so
-	COMMAND rm -f ${DESTDIR}/usr/local/lib/libpigpiod_if.so
-	COMMAND rm -f ${DESTDIR}/usr/local/lib/libpigpiod_if2.so
-	COMMAND rm -f ${DESTDIR}/usr/local/bin/pig2vcd
-	COMMAND rm -f ${DESTDIR}/usr/local/bin/pigpiod
-	COMMAND rm -f ${DESTDIR}/usr/local/bin/pigs
-	COMMAND cd ${CMAKE_SOURCE_DIR} && ${PY2_CMD}
-	COMMAND cd ${CMAKE_SOURCE_DIR} && ${PY3_CMD}
-	COMMAND rm -f ${DESTDIR}/usr/local/man/man1/pig*.1
-	COMMAND rm -f ${DESTDIR}/usr/local/man/man3/pig*.3
-	COMMAND ldconfig
-)
+include (CPack)
\ No newline at end of file
diff --git a/cmake/FindRT.cmake b/cmake/FindRT.cmake
new file mode 100644
index 0000000..db7c4de
--- /dev/null
+++ b/cmake/FindRT.cmake
@@ -0,0 +1,39 @@
+# FindRT.cmake - Try to find the RT library
+# Once done this will define
+#
+#  RT_FOUND - System has rt
+#  RT_INCLUDE_DIR - The rt include directory
+#  RT_LIBRARIES - The libraries needed to use rt
+#  RT_DEFINITIONS - Compiler switches required for using rt
+#
+# Also creates an import target called RT::RT
+
+find_path (RT_INCLUDE_DIR NAMES time.h
+  PATHS
+  /usr
+  /usr/local
+  /opt
+  PATH_SUFFIXES
+)
+
+find_library(RT_LIBRARIES NAMES rt
+  PATHS
+  /usr
+  /usr/local
+  /opt
+)
+
+include(FindPackageHandleStandardArgs)
+
+FIND_PACKAGE_HANDLE_STANDARD_ARGS(rt DEFAULT_MSG RT_LIBRARIES RT_INCLUDE_DIR)
+
+mark_as_advanced(RT_INCLUDE_DIR RT_LIBRARIES)
+
+if (NOT TARGET RT::RT)
+  add_library(RT::RT INTERFACE IMPORTED)
+
+  set_target_properties(RT::RT PROPERTIES
+    INTERFACE_INCLUDE_DIRECTORIES ${RT_INCLUDE_DIR}
+    INTERFACE_LINK_LIBRARIES ${RT_LIBRARIES}
+  )
+endif()
\ No newline at end of file
diff --git a/cmake/pigpioConfig.cmake b/cmake/pigpioConfig.cmake
new file mode 100644
index 0000000..7912526
--- /dev/null
+++ b/cmake/pigpioConfig.cmake
@@ -0,0 +1 @@
+include (${CMAKE_CURRENT_LIST_DIR}/pigpioTargets.cmake)
\ No newline at end of file
diff --git a/cmake/setup.py.in b/cmake/setup.py.in
new file mode 100644
index 0000000..a5913a2
--- /dev/null
+++ b/cmake/setup.py.in
@@ -0,0 +1,24 @@
+#!/usr/bin/env python
+
+from distutils.core import setup
+
+setup(name='pigpio',
+      version='1.44',
+      author='joan',
+      author_email='joan@abyz.me.uk',
+      maintainer='joan',
+      maintainer_email='joan@abyz.me.uk',
+      url='http://abyz.me.uk/rpi/pigpio/python.html',
+      description='Raspberry Pi GPIO module',
+      long_description='Raspberry Pi Python module to access the pigpio daemon',
+      download_url='http://abyz.me.uk/rpi/pigpio/pigpio.zip',
+      license='unlicense.org',
+      py_modules=['pigpio'],
+      keywords=['raspberrypi', 'gpio',],
+      classifiers=[
+         "Programming Language :: Python :: 2",
+         "Programming Language :: Python :: 3",
+      ],
+      package_dir={ '': '${CMAKE_CURRENT_SOURCE_DIR}'}
+     )
+
diff --git a/pigpio.3 b/pigpio.3
index e218ed1..cd77e18 100644
--- a/pigpio.3
+++ b/pigpio.3
@@ -1682,6 +1682,15 @@ will be a latency.
 
 .br
 
+.br
+If you want to track the level of more than one GPIO do so by
+maintaining the state in the callback.  Do not use \fBgpioRead\fP.
+Remember the event that triggered the callback may have
+happened several milliseconds before and the GPIO may have
+changed level many times since then.
+
+.br
+
 .br
 The tick value is the time stamp of the sample in microseconds, see
 \fBgpioTick\fP for more details.
@@ -4181,12 +4190,6 @@ queue and the master removes it.
 
 .br
 
-.br
-This function is not available on the BCM2711 (e.g. as
-used in the Pi4B).
-
-.br
-
 .br
 I can't get SPI to work properly.  I tried with a
 control word of 0x303 and swapped MISO and MOSI.
@@ -4249,14 +4252,37 @@ that mode until a different control word is sent.
 .br
 
 .br
-The BSC peripheral uses GPIO 18 (SDA) and 19 (SCL) in I2C mode
-and GPIO 18 (MOSI), 19 (SCLK), 20 (MISO), and 21 (CE) in SPI mode.  You
-need to swap MISO/MOSI between master and slave.
+GPIO used for models other than those based on the BCM2711.
 
 .br
 
 .br
-When a zero control word is received GPIO 18-21 will be reset
+      SDA   SCL   MOSI   SCLK   MISO   CE
+.br
+I2C   18    19    -      -      -      -
+.br
+SPI   -     -     18     19     20     21
+.br
+
+.br
+
+.br
+GPIO used for models based on the BCM2711 (e.g. the Pi4B).
+
+.br
+
+.br
+      SDA   SCL   MOSI   SCLK   MISO   CE
+.br
+I2C   10    11    -      -      -      -
+.br
+SPI   -     -     10     11     9      8
+.br
+
+.br
+
+.br
+When a zero control word is received the used GPIO will be reset
 to INPUT mode.
 
 .br
diff --git a/pigpio.c b/pigpio.c
index 409b981..7cd7cbf 100644
--- a/pigpio.c
+++ b/pigpio.c
@@ -25,7 +25,7 @@ OTHER DEALINGS IN THE SOFTWARE.
 For more information, please refer to <http://unlicense.org/>
 */
 
-/* pigpio version 74 */
+/* pigpio version 75 */
 
 /* include ------------------------------------------------------- */
 
@@ -4768,7 +4768,7 @@ int spiClose(unsigned handle)
    if (spiInfo[handle].state != PI_SPI_OPENED)
       SOFT_ERROR(PI_BAD_HANDLE, "bad handle (%d)", handle);
 
-   spiInfo[handle].state = PI_I2C_CLOSED;
+   spiInfo[handle].state = PI_SPI_CLOSED;
 
    if (!spiAnyOpen(spiInfo[handle].flags))
       spiTerm(spiInfo[handle].flags); /* terminate on last close */
@@ -10730,35 +10730,69 @@ int bbI2CZip(
 
 void bscInit(int mode)
 {
+   int sda, scl, miso, ce;
+
    bscsReg[BSC_CR]=0; /* clear device */
    bscsReg[BSC_RSR]=0; /* clear underrun and overrun errors */
    bscsReg[BSC_SLV]=0; /* clear I2C slave address */
    bscsReg[BSC_IMSC]=0xf; /* mask off all interrupts */
    bscsReg[BSC_ICR]=0x0f; /* clear all interrupts */
 
-   gpioSetMode(BSC_SDA_MOSI, PI_ALT3);
-   gpioSetMode(BSC_SCL_SCLK, PI_ALT3);
+   if (pi_is_2711)
+   {
+      sda = BSC_SDA_MOSI_2711;
+      scl = BSC_SCL_SCLK_2711;
+      miso = BSC_MISO_2711;
+      ce = BSC_CE_N_2711;
+   }
+   else
+   {
+      sda = BSC_SDA_MOSI;
+      scl = BSC_SCL_SCLK;
+      miso = BSC_MISO;
+      ce = BSC_CE_N;
+   }
+
+   gpioSetMode(sda, PI_ALT3);
+   gpioSetMode(scl, PI_ALT3);
 
    if (mode > 1) /* SPI uses all GPIO */
    {
-      gpioSetMode(BSC_MISO, PI_ALT3);
-      gpioSetMode(BSC_CE_N, PI_ALT3);
+      gpioSetMode(miso, PI_ALT3);
+      gpioSetMode(ce, PI_ALT3);
    }
 }
 
 void bscTerm(int mode)
 {
+   int sda, scl, miso, ce;
+
    bscsReg[BSC_CR] = 0; /* clear device */
    bscsReg[BSC_RSR]=0; /* clear underrun and overrun errors */
    bscsReg[BSC_SLV]=0; /* clear I2C slave address */
 
-   gpioSetMode(BSC_SDA_MOSI, PI_INPUT);
-   gpioSetMode(BSC_SCL_SCLK, PI_INPUT);
+   if (pi_is_2711)
+   {
+      sda = BSC_SDA_MOSI_2711;
+      scl = BSC_SCL_SCLK_2711;
+      miso = BSC_MISO_2711;
+      ce = BSC_CE_N_2711;
+   }
+   else
+   {
+      sda = BSC_SDA_MOSI;
+      scl = BSC_SCL_SCLK;
+      miso = BSC_MISO;
+      ce = BSC_CE_N;
+   }
+
+   gpioSetMode(sda, PI_INPUT);
+   gpioSetMode(scl, PI_INPUT);
 
    if (mode > 1)
    {
-      gpioSetMode(BSC_MISO, PI_INPUT);
-      gpioSetMode(BSC_CE_N, PI_INPUT);
+      gpioSetMode(miso, PI_INPUT);
+      gpioSetMode(ce, PI_INPUT);
    }
 }
 
@@ -10778,9 +10812,6 @@ int bscXfer(bsc_xfer_t *xfer)
 
    CHECK_INITED;
 
-   if (pi_is_2711)
-      SOFT_ERROR(PI_NOT_ON_BCM2711, "SPI/BSC slave not available on BCM2711");
-
    eventAlert[PI_EVENT_BSC].ignore = 1;
 
    if (xfer->control)
@@ -10794,7 +10825,7 @@ int bscXfer(bsc_xfer_t *xfer)
 
       if (mode > bscMode)
       {
-         bscInit(bscMode);
+         bscInit(mode);
          bscMode = mode;
       }
    }
diff --git a/pigpio.h b/pigpio.h
index 9f12497..7701b45 100644
--- a/pigpio.h
+++ b/pigpio.h
@@ -30,7 +30,7 @@ For more information, please refer to <http://unlicense.org/>
 #include <stdint.h>
 #include <pthread.h>
 
-#define PIGPIO_VERSION 74
+#define PIGPIO_VERSION 75
 
 /*TEXT
 
@@ -797,6 +797,11 @@ typedef void *(gpioThreadFunc_t) (void *);
 #define BSC_MISO     20
 #define BSC_CE_N     21
 
+#define BSC_SDA_MOSI_2711 10
+#define BSC_SCL_SCLK_2711 11
+#define BSC_MISO_2711      9
+#define BSC_CE_N_2711      8
+
 /* Longest busy delay */
 
 #define PI_MAX_BUSY_DELAY 100
@@ -1439,6 +1444,12 @@ once per level change since the last time the thread was activated.
 i.e. The active alert functions will get all level changes but there
 will be a latency.
 
+If you want to track the level of more than one GPIO do so by
+maintaining the state in the callback.  Do not use [*gpioRead*].
+Remember the event that triggered the callback may have
+happened several milliseconds before and the GPIO may have
+changed level many times since then.
+
 The tick value is the time stamp of the sample in microseconds, see
 [*gpioTick*] for more details.
 
@@ -2913,9 +2924,6 @@ The output process is simple. You simply append data to the FIFO
 buffer on the chip.  This works like a queue, you add data to the
 queue and the master removes it.
 
-This function is not available on the BCM2711 (e.g. as
-used in the Pi4B).
-
 I can't get SPI to work properly.  I tried with a
 control word of 0x303 and swapped MISO and MOSI.
 
@@ -2947,11 +2955,19 @@ in rxBuf.
 Note that the control word sets the BSC mode.  The BSC will stay in
 that mode until a different control word is sent.
 
-The BSC peripheral uses GPIO 18 (SDA) and 19 (SCL) in I2C mode
-and GPIO 18 (MOSI), 19 (SCLK), 20 (MISO), and 21 (CE) in SPI mode.  You
-need to swap MISO/MOSI between master and slave.
+GPIO used for models other than those based on the BCM2711.
 
-When a zero control word is received GPIO 18-21 will be reset
+    @ SDA @ SCL @ MOSI @ SCLK @ MISO @ CE
+I2C @ 18  @ 19  @ -    @ -    @ -    @ -
+SPI @ -   @ -   @ 18   @ 19   @ 20   @ 21
+
+GPIO used for models based on the BCM2711 (e.g. the Pi4B).
+
+    @ SDA @ SCL @ MOSI @ SCLK @ MISO @ CE
+I2C @ 10  @ 11  @ -    @ -    @ -    @ -
+SPI @ -   @ -   @ 10   @ 11   @ 9    @ 8
+
+When a zero control word is received the used GPIO will be reset
 to INPUT mode.
 
 The returned function value is the status of the transfer (see below).
diff --git a/pigpio.py b/pigpio.py
index 0e2a0a1..cfaf845 100644
--- a/pigpio.py
+++ b/pigpio.py
@@ -330,7 +330,7 @@ import threading
 import os
 import atexit
 
-VERSION = "1.45"
+VERSION = "1.46"
 
 exceptions = True
 
@@ -3557,13 +3557,9 @@ class pi():
       buffer on the chip.  This works like a queue, you add data to the
       queue and the master removes it.
 
-      This function is not available on the BCM2711 (e.g. as
-      used in the Pi4B).
-
       I can't get SPI to work properly.  I tried with a
       control word of 0x303 and swapped MISO and MOSI.
 
-
       The function sets the BSC mode, writes any data in
       the transmit buffer to the BSC transmit FIFO, and
       copies any data in the BSC receive FIFO to the
@@ -3580,12 +3576,19 @@ class pi():
       Note that the control word sets the BSC mode.  The BSC will
       stay in that mode until a different control word is sent.
 
-      The BSC peripheral uses GPIO 18 (SDA) and 19 (SCL)
-      in I2C mode and GPIO 18 (MOSI), 19 (SCLK), 20 (MISO),
-      and 21 (CE) in SPI mode.  You need to swap MISO/MOSI
-      between master and slave.
+      GPIO used for models other than those based on the BCM2711.
 
-      When a zero control word is received GPIO 18-21 will be reset
+          @ SDA @ SCL @ MOSI @ SCLK @ MISO @ CE
+      I2C @ 18  @ 19  @ -    @ -    @ -    @ -
+      SPI @ -   @ -   @ 18   @ 19   @ 20   @ 21
+
+      GPIO used for models based on the BCM2711 (e.g. the Pi4B).
+
+          @ SDA @ SCL @ MOSI @ SCLK @ MISO @ CE
+      I2C @ 10  @ 11  @ -    @ -    @ -    @ -
+      SPI @ -   @ -   @ 10   @ 11   @ 9    @ 8
+
+      When a zero control word is received the used GPIO will be reset
       to INPUT mode.
 
       bsc_control consists of the following bits:
@@ -3684,10 +3687,10 @@ class pi():
       (and will contain the error code).
 
       Note that an i2c_address of 0 may be used to close
-      the BSC device and reassign the used GPIO (18/19)
-      as inputs.
+      the BSC device and reassign the used GPIO as inputs.
 
-      This example assumes GPIO 2/3 are connected to GPIO 18/19.
+      This example assumes GPIO 2/3 are connected to GPIO 18/19
+      (GPIO 10/11 on the BCM2711).
 
       ...
       #!/usr/bin/env python
@@ -4939,6 +4942,37 @@ class pi():
       A GPIO may have multiple callbacks (although I can't think of
       a reason to do so).
 
+      The GPIO are sampled at a rate set when the pigpio daemon
+      is started (default 5 us).
+
+      The number of samples per second is given in the following table.
+
+      . .
+                    samples
+                    per sec
+
+               1  1,000,000
+               2    500,000
+      sample   4    250,000
+      rate     5    200,000
+      (us)     8    125,000
+              10    100,000
+      . .
+
+      GPIO level changes shorter than the sample rate may be missed.
+
+      The daemon software which generates the callbacks is triggered
+      1000 times per second.  The callbacks will be called once per
+      level change since the last time they were called.
+      i.e. The callbacks will get all level changes but there will
+      be a latency.
+
+      If you want to track the level of more than one GPIO do so by
+      maintaining the state in the callback.  Do not use [*read*].
+      Remember the event that triggered the callback may have
+      happened several milliseconds before and the GPIO may have
+      changed level many times since then.
+
       ...
       def cbf(gpio, level, tick):
          print(gpio, level, tick)
diff --git a/pigpiod_if2.3 b/pigpiod_if2.3
index 1c9291c..33c55e9 100644
--- a/pigpiod_if2.3
+++ b/pigpiod_if2.3
@@ -5920,6 +5920,66 @@ tick        32 bit   The number of microseconds since boot
 
 .EE
 
+.br
+
+.br
+The GPIO are sampled at a rate set when the pigpio daemon
+is started (default 5 us).
+
+.br
+
+.br
+The number of samples per second is given in the following table.
+
+.br
+
+.br
+
+.EX
+              samples
+.br
+              per sec
+.br
+
+.br
+         1  1,000,000
+.br
+         2    500,000
+.br
+sample   4    250,000
+.br
+rate     5    200,000
+.br
+(us)     8    125,000
+.br
+        10    100,000
+.br
+
+.EE
+
+.br
+
+.br
+GPIO level changes shorter than the sample rate may be missed.
+
+.br
+
+.br
+The daemon software which generates the callbacks is triggered
+1000 times per second.  The callbacks will be called once per
+level change since the last time they were called.
+i.e. The callbacks will get all level changes but there will
+be a latency.
+
+.br
+
+.br
+If you want to track the level of more than one GPIO do so by
+maintaining the state in the callback.  Do not use \fBgpio_read\fP.
+Remember the event that triggered the callback may have
+happened several milliseconds before and the GPIO may have
+changed level many times since then.
+
 .IP "\fBint callback_ex(int pi, unsigned user_gpio, unsigned edge, CBFuncEx_t f, void *userdata)\fP"
 .IP "" 4
 This function initialises a new callback.
@@ -6072,12 +6132,6 @@ queue and the master removes it.
 
 .br
 
-.br
-This function is not available on the BCM2711 (e.g. as
-used in the Pi4B).
-
-.br
-
 .br
 I can't get SPI to work properly.  I tried with a
 control word of 0x303 and swapped MISO and MOSI.
@@ -6160,14 +6214,37 @@ that mode until a different control word is sent.
 .br
 
 .br
-The BSC peripheral uses GPIO 18 (SDA) and 19 (SCL) in I2C mode
-and GPIO 18 (MOSI), 19 (SCLK), 20 (MISO), and 21 (CE) in SPI mode.  You
-need to swap MISO/MOSI between master and slave.
+GPIO used for models other than those based on the BCM2711.
 
 .br
 
 .br
-When a zero control word is received GPIO 18-21 will be reset
+      SDA   SCL   MOSI   SCLK   MISO   CE
+.br
+I2C   18    19    -      -      -      -
+.br
+SPI   -     -     18     19     20     21
+.br
+
+.br
+
+.br
+GPIO used for models based on the BCM2711 (e.g. the Pi4B).
+
+.br
+
+.br
+      SDA   SCL   MOSI   SCLK   MISO   CE
+.br
+I2C   10    11    -      -      -      -
+.br
+SPI   -     -     10     11     9      8
+.br
+
+.br
+
+.br
+When a zero control word is received the used GPIO will be reset
 to INPUT mode.
 
 .br
@@ -6390,8 +6467,7 @@ If there was an error the status will be less than zero
 
 .br
 Note that an i2c_address of 0 may be used to close
-the BSC device and reassign the used GPIO (18/19)
-as inputs.
+the BSC device and reassign the used GPIO as inputs.
 
 .IP "\fBint event_callback(int pi, unsigned event, evtCBFunc_t f)\fP"
 .IP "" 4
diff --git a/pigpiod_if2.c b/pigpiod_if2.c
index 36f01aa..90fb5fb 100644
--- a/pigpiod_if2.c
+++ b/pigpiod_if2.c
@@ -25,7 +25,7 @@ OTHER DEALINGS IN THE SOFTWARE.
 For more information, please refer to <http://unlicense.org/>
 */
 
-/* PIGPIOD_IF2_VERSION 16 */
+/* PIGPIOD_IF2_VERSION 17 */
 
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/pigpiod_if2.h b/pigpiod_if2.h
index fb214df..8d6f132 100644
--- a/pigpiod_if2.h
+++ b/pigpiod_if2.h
@@ -30,7 +30,7 @@ For more information, please refer to <http://unlicense.org/>
 
 #include "pigpio.h"
 
-#define PIGPIOD_IF2_VERSION 16
+#define PIGPIOD_IF2_VERSION 17
 
 /*TEXT
 
@@ -3352,6 +3352,37 @@ tick        32 bit   The number of microseconds since boot
                      WARNING: this wraps around from
                      4294967295 to 0 roughly every 72 minutes
 . .
+
+The GPIO are sampled at a rate set when the pigpio daemon
+is started (default 5 us).
+
+The number of samples per second is given in the following table.
+
+. .
+              samples
+              per sec
+
+         1  1,000,000
+         2    500,000
+sample   4    250,000
+rate     5    200,000
+(us)     8    125,000
+        10    100,000
+. .
+
+GPIO level changes shorter than the sample rate may be missed.
+
+The daemon software which generates the callbacks is triggered
+1000 times per second.  The callbacks will be called once per
+level change since the last time they were called.
+i.e. The callbacks will get all level changes but there will
+be a latency.
+
+If you want to track the level of more than one GPIO do so by
+maintaining the state in the callback.  Do not use [*gpio_read*].
+Remember the event that triggered the callback may have
+happened several milliseconds before and the GPIO may have
+changed level many times since then.
 D*/
 
 /*F*/
@@ -3442,9 +3473,6 @@ The output process is simple. You simply append data to the FIFO
 buffer on the chip.  This works like a queue, you add data to the
 queue and the master removes it.
 
-This function is not available on the BCM2711 (e.g. as
-used in the Pi4B).
-
 I can't get SPI to work properly.  I tried with a
 control word of 0x303 and swapped MISO and MOSI.
 
@@ -3486,11 +3514,19 @@ less than requested if the FIFO already contained untransmitted data).
 Note that the control word sets the BSC mode.  The BSC will stay in
 that mode until a different control word is sent.
 
-The BSC peripheral uses GPIO 18 (SDA) and 19 (SCL) in I2C mode
-and GPIO 18 (MOSI), 19 (SCLK), 20 (MISO), and 21 (CE) in SPI mode.  You
-need to swap MISO/MOSI between master and slave.
+GPIO used for models other than those based on the BCM2711.
 
-When a zero control word is received GPIO 18-21 will be reset
+    @ SDA @ SCL @ MOSI @ SCLK @ MISO @ CE
+I2C @ 18  @ 19  @ -    @ -    @ -    @ -
+SPI @ -   @ -   @ 18   @ 19   @ 20   @ 21
+
+GPIO used for models based on the BCM2711 (e.g. the Pi4B).
+
+    @ SDA @ SCL @ MOSI @ SCLK @ MISO @ CE
+I2C @ 10  @ 11  @ -    @ -    @ -    @ -
+SPI @ -   @ -   @ 10   @ 11   @ 9    @ 8
+
+When a zero control word is received the used GPIO will be reset
 to INPUT mode.
 
 control consists of the following bits.
@@ -3598,8 +3634,7 @@ If there was an error the status will be less than zero
 (and will contain the error code).
 
 Note that an i2c_address of 0 may be used to close
-the BSC device and reassign the used GPIO (18/19)
-as inputs.
+the BSC device and reassign the used GPIO as inputs.
 D*/
 
 /*F*/
diff --git a/pigs.1 b/pigs.1
index 3b5d30b..ca31392 100644
--- a/pigs.1
+++ b/pigs.1
@@ -925,10 +925,6 @@ The output process is simple. You simply append data to the FIFO
 buffer on the chip.  This works like a queue, you add data to the
 queue and the master removes it.
 
-.br
-This function is not available on the BCM2711 (e.g. as
-used in the Pi4B).
-
 .br
 I can't get SPI to work properly.  I tried with a
 control word of 0x303 and swapped MISO and MOSI.
@@ -950,12 +946,31 @@ For I2C use a control word of (I2C address << 16) + 0x305.
 E.g. to talk as I2C slave with address 0x13 use 0x130305.
 
 .br
-The BSC peripheral uses GPIO 18 (SDA) and 19 (SCL) in I2C mode
-and GPIO 18 (MOSI), 19 (SCLK), 20 (MISO), and 21 (CE) in SPI mode.  You
-need to swap MISO/MOSI between master and slave.
+GPIO used for models other than those based on the BCM2711.
 
 .br
-When a zero control word is received GPIO 18-21 will be reset
+
+.EX
+      SDA   SCL   MOSI   SCLK   MISO   CE
+I2C   18    19    -      -      -      -
+SPI   -     -     18     19     20     21
+
+.EE
+
+.br
+GPIO used for models based on the BCM2711 (e.g. the Pi4B).
+
+.br
+
+.EX
+      SDA   SCL   MOSI   SCLK   MISO   CE
+I2C   10    11    -      -      -      -
+SPI   -     -     10     11     9      8
+
+.EE
+
+.br
+When a zero control word is received the used GPIO will be reset
 to INPUT mode.
 
 .br
@@ -1031,7 +1046,8 @@ TB      transmit busy
 .EE
 
 .br
-This example assumes that GPIO 2/3 are connected to GPIO 18/19.
+This example assumes that GPIO 2/3 are connected to GPIO 18/19
+(GPIO 10/11 on the BCM2711).
 
 .br
 
diff --git a/setup.py b/setup.py
index 00f70a0..023a2c4 100644
--- a/setup.py
+++ b/setup.py
@@ -3,7 +3,7 @@
 from distutils.core import setup
 
 setup(name='pigpio',
-      version='1.45',
+      version='1.46',
       author='joan',
       author_email='joan@abyz.me.uk',
       maintainer='joan',