Updated docs, begin I2C impl

Author: calcinai

README.md

@@ -75,7 +75,8 @@ $board->getLoop()->run();
 
 GPIO (input) is the default mode of the pin objects. Alternate functions can be accessed by using the ```->setFunction(PinFunction::x)``` method.  It is
  recommended to use the function names as opposed to `ALT0..5` unless you know exactly what you're doing, as quite a lot are reserved.
-A few useful classes are also included for digital interaction.
+A few useful classes are also included for digital interaction.  With the default python-mmap, you can expect a raw transition speed of ~15kHz, with the
+native extension, it's more like 50kHz on a Pi 3.
 
 
 ### PWM

examples/benchmark.php

@@ -0,0 +1,29 @@
+<?php
+/**
+ * @package    phpi
+ * @author     Michael Calcinai <[email protected]>
+ */
+
+include __DIR__.'/../vendor/autoload.php';
+
+use Calcinai\PHPi\Pin\PinFunction;
+
+$board = \Calcinai\PHPi\Factory::create();
+
+$pin = $board->getPin(18);
+$pin->setFunction(PinFunction::OUTPUT);
+
+$start = microtime(true);
+
+for($i=0; $i<1e4; $i++){
+    $pin->high(true);
+    $pin->low(true);
+}
+
+$time = (microtime(true) - $start);
+$ms = $time * 1000;
+$writes = $i * 2;
+
+$writes_sec = $writes / $time;
+
+printf("%0.2dms for %d transitions (%d writes), %d writes/sec\n", $ms, $i, $writes, $writes_sec);

examples/i2c.php

@@ -0,0 +1,5 @@
+<?php
+/**
+ * @package    phpi
+ * @author     Michael Calcinai <[email protected]>
+ */

src/PHPi/Board.php

@@ -9,6 +9,7 @@
 
 use Calcinai\PHPi\Board\BoardInterface;
 use Calcinai\PHPi\Peripheral\Clock;
+use Calcinai\PHPi\Peripheral\I2C;
 use Calcinai\PHPi\Peripheral\PWM;
 use Calcinai\PHPi\Peripheral\Register;
 use Calcinai\PHPi\Peripheral\SPI;
@@ -76,6 +77,11 @@ abstract class Board implements BoardInterface {
      */
     private $spis;
 
+    /**
+     * @var I2C[]
+     */
+    private $i2cs;
+
 
     public function __construct(LoopInterface $loop) {
         $this->loop = $loop;
@@ -138,6 +144,18 @@ public function getSPI($spi_number){
         return $this->spis[$spi_number];
     }
 
+    /**
+     * @param $i2c_number
+     * @return SPI
+     */
+    public function getI2C($i2c_number){
+        if(!isset($this->i2cs[$i2c_number])){
+            $this->i2cs[$i2c_number] = new I2C($this, $i2c_number);
+        }
+
+        return $this->i2cs[$i2c_number];
+    }
+
     /**
      * @return Register\GPIO
      */

src/PHPi/Pin.php

@@ -209,8 +209,11 @@ public function assertFunction(array $valid_functions){
     }
 
 
-    public function high(){
-        $this->assertFunction([PinFunction::OUTPUT]);
+    public function high($fast_mode = false){
+
+        if(!$fast_mode){
+            $this->assertFunction([PinFunction::OUTPUT]);
+        }
 
         $this->setInternalLevel(self::LEVEL_HIGH);
 
@@ -220,8 +223,11 @@ public function high(){
         return $this;
     }
 
-    public function low(){
-        $this->assertFunction([PinFunction::OUTPUT]);
+    public function low($fast_mode = false){
+
+        if(!$fast_mode){
+            $this->assertFunction([PinFunction::OUTPUT]);
+        }
 
         $this->setInternalLevel(self::LEVEL_LOW);