touchPanel.TouchPanel Class Reference

A driver class for a 4-wire resistive touch panel. More...

Public Member Functions
def	__init__ (self, pyb.Pin YmPin, pyb.Pin YpPin, pyb.Pin XmPin, pyb.Pin XpPin, PrintQueue print_queue=None)
	Initializes a touchpad object. More...
def	calibrate (self, touch_calib_status=None)
	Calibrates the touchpad. More...
def	scan (self)
	Scans the touch panel and returns the position of contact. More...

Public Attributes
	YmPin
	-Y Pin More...
	YpPin
	+Y Pin More...
	XmPin
	-X Pin More...
	XpPin
	+X Pin More...
	tim
	Timer for the ADC. More...
	buf
	Buffer for readings. More...
	calibCoeffs
	Calibration Coefficients. More...
	print_queue
	Print queue object. More...
	xADC
	ADC object for the X scans. More...
	yzADC
	ADC object for the Y and Z scans. More...

Detailed Description

A driver class for a 4-wire resistive touch panel.

Contains methods for initializing, calibrating, and scanning a touch panel.

Constructor & Destructor Documentation

__init__()

def touchPanel.TouchPanel.__init__	(		self,
		pyb.Pin	YmPin,
		pyb.Pin	YpPin,
		pyb.Pin	XmPin,
		pyb.Pin	XpPin,
		PrintQueue	print_queue = None
	)

Initializes a touchpad object.

Touchpad pin modes are preconfigured for the first X scan. A timer is also created for use by the ADC.read_timed() method. A buffer is also preallocated to hold the values from ADC.read_timed()

Parameters

YmPin	Negative pin of the Y-dimension circuit.
YpPin	Positive pin of the Y-dimension circuit.
XmPin	Negative pin of the X-dimension circuit.
XpPin	Positive pin of the X_dimension circuit.
print_queue	A shared variable used for passing print statements out to the print function in taskUser.py

Member Function Documentation

calibrate()

def touchPanel.TouchPanel.calibrate	(		self,
			touch_calib_status = None
	)

Calibrates the touchpad.

Requests 5 known points be pressed by the user: (-80, -40), (-80, 40), (0, 0), (80, -40), (80, 40) These values are processed to determine calibration coefficients.

Parameters

touch_calib_status

A shared variable used to indicate when the calibration process is finished.

scan()

def touchPanel.TouchPanel.scan

(

self

)

Scans the touch panel and returns the position of contact.

The panel is scanned in X, Z, and Y, in that order. X and Y return the position in mm, and Z returns True if contact is made, otherwise, False is returned.

Member Data Documentation

buf

touchPanel.TouchPanel.buf

Buffer for readings.

ADC readings are read into this buffer before being averaged. Changing it's size changes how many readings are made.

calibCoeffs

touchPanel.TouchPanel.calibCoeffs

Calibration Coefficients.

An array holding the correlations used to convert ADC readings to useful positions.

print_queue

touchPanel.TouchPanel.print_queue

Print queue object.

Items to be printed are added to the queue using this object.

tim

touchPanel.TouchPanel.tim

Timer for the ADC.

Used to trigger readings from ADC.read_timed()

xADC

touchPanel.TouchPanel.xADC

ADC object for the X scans.

Attached to the +Y pin

XmPin

touchPanel.TouchPanel.XmPin

-X Pin

Negative pin of the X-dimension circuit.

XpPin

touchPanel.TouchPanel.XpPin

+X Pin

Positive pin of the X_dimension circuit.

YmPin

touchPanel.TouchPanel.YmPin

-Y Pin

Negative pin of the Y-dimension circuit.

YpPin

touchPanel.TouchPanel.YpPin

+Y Pin

Positive pin of the Y-dimension circuit.

yzADC

touchPanel.TouchPanel.yzADC

ADC object for the Y and Z scans.

Attached to the +X pin

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

• ME305_code/Lab0xFF/touchPanel.py