Encoder class

1 files changed, 74 insertions, 0 deletions

diff --git a/System_Python/encoder.py b/System_Python/encoder.py
new file mode 100644
index 0000000..b70fac6
--- /dev/null
+++ b/System_Python/encoder.py
@@ -0,0 +1,74 @@
+# Import required modules
+import RPi.GPIO as GPIO
+import time
+import math
+
+# Constants: parameters that the caller cannot modify
+# Delay: Minimum delay necessary after pull pin low to read input
+delay = 0.0000005
+
+# Encoder Class
+# This controls the motor at the given IO
+class Encoder:
+    def __init__(self, clk_pin, cs_pin, data_pin):
+        # Set the board IO (just in case it hasn't been done yet)
+        GPIO.setmode(GPIO.BCM)
+        # Setup class varaiable
+        self.offset=0
+        self.clk_pin = clk_pin
+        self.cs_pin = cs_pin
+        self.data_pin = data_pin
+        # Setup the IO
+        try:
+            GPIO.setup(self.clk_pin,GPIO.OUT)
+            GPIO.setup(self.cs_pin,GPIO.OUT)
+            GPIO.setup(self.data_pin,GPIO.IN)
+            # Setup the CS and CLK to be high
+            GPIO.output(PIN_CLK,1)
+            GPIO.output(PIN_CS,1)
+        except:
+            print("ERROR. Unable to setup the configuration required")
+        # Wait some time to before reading
+        time.sleep(0.5)
+    def setZero(self):
+        # Take current position as zero
+        self.offset=self.readPosition('Raw')
+    def clockup(self):
+        GPIO.output(self.clk_pin,1)
+    def clockdown(self):
+        GPIO.output(self.clk_pin,0)
+    def readPosition(self, format):
+        # Most of this is based of timing diagram of encoder
+        # Pull CS low to start reading
+        GPIO.output(self.cs_pin,0) 
+        # Delay necessary before reading is ready
+        time.sleep(delay*2)
+        data = 0
+        # Clockdown necessary before reading 
+        self.clockdown()
+        # Go through 10 bits needed to read
+        for i in range(0,10): 
+            # Clock up to start reading one bit
+            self.clockup()
+            # Shift data left and insert input 
+            data<<=1  
+            data|=GPIO.input(self.data_pin)
+            # Clock down after finish reading
+            self.clockdown()
+        # Pull CS high after finish reading
+        GPIO.output(self.cs_pin,1)
+        # Format with offset, Max is 1024
+        data=(data+offset)%1024
+        # Data is linearly mapped
+        if format=="Raw":
+            return data
+        elif format=="Degrees":
+            degrees=data/(1024/360)
+            return degrees
+        elif format=="Radian":
+            radians=data/(1024/(2*math.pi))
+            return radians
+        else:
+            print("ERROR. Invalid format (Raw, Degrees, Radians)")
+            return None
+