encoder.encoder Class Reference

Encoder driver class. More...

Public Member Functions
def	__init__ (self, pin1, pin2, timerNum, debugFlag=False)
	Constructor for class encoder More...
def	update (self)
	Updates encoder position. More...
def	get_position (self)
	Retrieves the current encoder position. More...
def	set_position (self, newPosition)
	Sets the encoder position. More...
def	get_delta (self)
	Retrieves the last change in encoder position (in ticks, not angle) More...
def	get_speed (self)
	Gets the current encoder speed in rpm. More...

Public Attributes
	debugFlag
	Debugging flag for print statements to be shown in Putty.
	timerNum
	Timer number on Nucleo board for encoder.
	pin1
	Pin 1 for encoder.
	pin2
	Pin 2 for encoder.
	tim
	definition of timer More...
	tim_ch1
	First encoder timer channel.
	tim_ch2
	Second encoder timer channel.
	lastTime
	Previous time, used for determining speed.
	currentTime
	Current absolute time in microseconds.
	lastPos
	Last position, updated at the end of each encoder update.
	theta
	Current angle (in degrees) of encoder.
	speed
	Current speed (in rpm) of encoder.
	realPeriod
	Time between updates, used for determining speed.
	currentPos
	Current encoder count.
	deltaTicks
	Difference in encoder count since last update. More...

Detailed Description

Encoder driver class.

Class for implementing methods related to encoders, such as getting the most recent position or speed or updating the count.

Constructor & Destructor Documentation

__init__()

def encoder.encoder.__init__	(		self,
			pin1,
			pin2,
			timerNum,
			debugFlag = False
	)

Constructor for class encoder

Parameters

pin1	Encoder pin # 1
pin2	Encoder pin # 2
timerNum	Corresponding timer based on datasheet
debugFlag	Debugging flag set to True or False

Member Function Documentation

get_delta()

def encoder.encoder.get_delta

(

self

)

Retrieves the last change in encoder position (in ticks, not angle)

Can be called from the PC side script

Returns

Delta, last adjusted change in enooder count

get_position()

def encoder.encoder.get_position

(

self

)

Retrieves the current encoder position.

Used by the controller task, as well as being callable by key press from the PC script

Returns

Theta, current encoder position

get_speed()

def encoder.encoder.get_speed

(

self

)

Gets the current encoder speed in rpm.

Used by the controller task, as well as being callable by key press from the PC script

Returns

Omega, current speed measured by encoder

set_position()

def encoder.encoder.set_position	(		self,
			newPosition
	)

Sets the encoder position.

Can be called from the front end to zero an encoder position

Parameters

newPosition

Takes in the new desired encoder position value

update()

def encoder.encoder.update

(

self

)

Updates encoder position.

This method implements an alogrithm developed in lecture for interpreting tick count changes into correct changes in encoder angular displacement. The encoder count can overflow or underflow, so these values are not enough on their own.

Member Data Documentation

deltaTicks

encoder.encoder.deltaTicks

Difference in encoder count since last update.

This value will be adjusted based on algorithm

tim

encoder.encoder.tim

definition of timer

Period of 35535 (encoder count before overflow occurs), prescaler of 0

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The documentation for this class was generated from the following file:

• encoder.py