Update README.md

diff --git a/README.md b/README.md
index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..30ff61be7b70c1a68e69edbaf833e7d502d70d89 100644 (file)
--- a/README.md
+++ b/README.md
@@ -0,0 +1,96 @@
+# pigpio\r
+pigpio is a C library for the Raspberry which allows control of the\r
+general purpose input outputs (gpios).\r
+\r
+Features\r
+\r
+    sampling and time-stamping of gpios 0-31 between 100,000 and 1,000,000 times per second.\r
+\r
+    provision of PWM on any number of the user gpios simultaneously.\r
+\r
+    provision of servo pulses on any number of the user gpios simultaneously.\r
+\r
+    callbacks when any of gpios 0-31 change state (callbacks receive the time of the event\r
+    accurate to a few microseconds).\r
+\r
+    notifications via pipe when any of gpios 0-31 change state.\r
+\r
+    callbacks at timed intervals.\r
+\r
+    reading/writing all of the gpios in a bank (0-31, 32-53) as a single operation.\r
+\r
+    individually setting gpio modes, reading and writing.\r
+\r
+    socket and pipe interfaces for the bulk of the functionality in addition to the\r
+    underlying C library calls.\r
+\r
+    the construction of arbitrary waveforms to give precise timing of output gpio\r
+    level changes (accurate to a few microseconds).\r
+\r
+    software serial links using any user gpio.\r
+\r
+    rudimentary permission control through the socket and pipe interfaces so users\r
+    can be prevented from "updating" inappropriate gpios.\r
+\r
+    creating and running scripts on the pigpio daemon.\r
+\r
+Interfaces\r
+\r
+The library provides a number of control interfaces\r
+\r
+    the C function interface\r
+\r
+    the /dev/pigpio pipe interface\r
+\r
+    the socket interface (used by the pigs utility and the Python module)\r
+\r
+Utilities\r
+\r
+A number of utility programs are provided\r
+\r
+    the pigpiod daemon.\r
+    the Python module.\r
+\r
+    the pigs command line utility.\r
+\r
+    the pig2vcd utility which converts notifications into the value change dump (VCD)\r
+    format (useful for viewing digital waveforms with GTKWave).\r
+\r
+gpios\r
+\r
+ALL gpios are identified by their Broadcom number.  See elinux.org\r
+\r
+There are 54 gpios in total, arranged in two banks.\r
+\r
+Bank 1 contains gpios 0-31.  Bank 2 contains gpios 32-54.\r
+\r
+A user should only manipulate gpios in bank 1.\r
+\r
+There are at least three types of board.\r
+\r
+Type 1\r
+\r
+    26 pin header (P1).\r
+\r
+    Hardware revision numbers of 2 and 3.\r
+\r
+    User gpios 0-1, 4, 7-11, 14-15, 17-18, 21-25.\r
+\r
+Type 2\r
+\r
+    26 pin header (P1) and an additional 8 pin header (P5).\r
+\r
+    Hardware revision numbers of 4, 5, 6, and 15.\r
+\r
+    User gpios 2-4, 7-11, 14-15, 17-18, 22-25, 27-31.\r
+\r
+Type 3\r
+\r
+    40 pin expansion header (J8).\r
+\r
+    Hardware revision numbers of 16 or greater.\r
+\r
+    User gpios 2-27 (0 and 1 are reserved).\r
+\r
+It is safe to read all the gpios. If you try to write a system gpio or change\r
+its mode you can crash the Pi or corrupt the data on the SD card.\r