Updated Mk1 code example (markdown)

Mk1-code-example.md

@@ -4,13 +4,64 @@ The first thing to do is to grab the 640Mk1 repository (or the https://github.co
 
 Put the files **Adafruit_I2C.py** and **Adafruit_PWM_Servo_Driver.py** in your project directory (or path), then create a new file and populate it with the following:
 
+Grab the required modules
+
     import RPi.GPIO as GPIO
     import time
     from Adafruit_PWM_Servo_Driver import PWM
 
-Grab the required modules
+Set up the PWM address and frequency
 
     pwm = PWM( 0x60, debug=False)
     pwm.setPWMFreq(1600)
 
-Set up the PWM address and frequency
+Set up the Motor Driver modes (this will change for Mk2) There is one pin controlling the mode of each of the three drivers.
+
+    GPIO.setmode(GPIO.BCM)
+    GPIO.setup(17, GPIO.OUT)
+    GPIO.setup(27, GPIO.OUT)
+    GPIO.setup(22, GPIO.OUT)
+    # set mode to en/phase
+    GPIO.output(17, GPIO.HIGH)
+    GPIO.output(27, GPIO.HIGH)
+    GPIO.output(22, GPIO.HIGH)
+
+The motor drivers can work in two ways, the default is IN/IN, when the mode pin for the driver is pushed high then it switches to EN/PHASE - both use two signals.
+
+IN/IN works as follows
+
+0 - 0 = coast
+0 - 1 = reverse
+1 - 0 = forward
+1 - 1 = brake
+
+1 = HIGH, 0 = LOW. You can PWM the high values for reverse and forward - so 4095 = full speed, 3000 = slower, etc.
+
+EN/PHASE is a lot simpler.
+
+0 - x = coast
+1 - 0 = forward
+1 - 1 = reverse
+
+There is no brake in this mode, using PWM on the Enable (EN) signal allows speed control, the other signal should be full Low or High.
+
+So, we've switch to EN/PHASE in this example - next set up PWM channels.
+
+    in1 = 5 #phase
+    in2 = 4 #enable
+    
+    in3 = 8 #phase
+    in4 = 9 #enable
+    
+    in5 = 0 #phase
+    in6 = 1 #enable
+    
+    in7 = 2 #phase
+    in8 = 3 #enable
+    
+    in9 = 10 #phase
+    in10 = 11 #enable
+    
+    in11 = 7 #phase
+    in12 = 6 #enable
+