Component: Touch Screen (Resistive) (Graphical Library)

Author	Matrix TSL
Version	1.0
Category	Graphical Library

Touch Screen (Resistive) component

Routines for reading a simple resistive touch screen directly without interface IC.

Version information

Library Version, Component Version, Date, Author, Info
9, 1.0, 26-07-24, BR, Renamed component to match other touchscreen components

Detailed description

No detailed description exists yet for this component

Examples

An example of how to calibrate and read a resistive touch display overlay using the component.

Resistive Touch Demo

Calibration is stored into EEPROM memory so as to avoid having to repeat it on every power up.

Macro reference

Calibrate

	Calibrate
Performs a calibration routine which draws a circle at the top left of the screen followed by the bottom right of the screen, from these coordinates the component can work out the corresponding X,Y pixel coordinate.
- UINT	Margin
Margin from the edge of the display, Range 0-63
- UINT	Radius
Radius of the calibration touch marker, should be <= margin
- VOID	Return

GetCalibrationValues

	GetCalibrationValues
Returns one of five calibration values used to configure the touchscreen. Populated automatically after running the calibration macro. Allows calibration data to be retrieved and stored into EEPROM by the user.
- BYTE	Index
Range: 0-4 Where 0=Xmin, 1=Xmax, 2=Ymin, 3=Ymax, 4=Flags
- UINT	Return

GetCoord

	GetCoord
Gets the coordinate from the last valid touch event
- BYTE	Index
0=X, 1=Y
- UINT	Return

IsTouched

	IsTouched
Check to see if display has been touched
- BOOL	Return

SetCalibrationValues

	SetCalibrationValues
Sets the calibration values used to configure the touchscreen. Allows the touchscreen to be re-calibrated from EE memory after a power cycle without re-running the calibration macro.
- UINT	Xmin
Calibration value ADC representin Min X
- UINT	Xmax
Calibration value ADC representin Max X
- UINT	Ymin
Calibration value ADC representin Min Y
- UINT	Ymax
Calibration value ADC representin Max Y
- UINT	Flags
Flags variable containing margin and X/Y flip status
- VOID	Return

SetOrientation

	SetOrientation
Sets the orientation of the touchscreen to match the orientation of the graphical display.
- BYTE	Orientation
Range: 0-3 default = 0
- VOID	Return

Property reference

	Properties
	LinkTo
	Connections
	XP Pin
	XM Pin
	YP Pin
	YM Pin
	XM Analog Pin
	YP Analog Pin
	Configuration
	X Pixel
	Y Pixel
	Trigger Pressure
Reading between X and Y which signifies a valid touch pressure.
	Acceptable Noise
Amount of acceptable noise on the input between samples before we allow a valid touch to be recorded.
	Sense Loop Count
Number of times to sample and compare the touch to confirm a valid touch press.
	Average ADC Count
Number of ADC samples used to create an averaged ADC input reading to help reduce input noise.
	Sample Timing (us)
Microsecond delay in between each of the averaged samples.
	ADC options
	VRef option
Defines what is used as the ADC maximum reference. ADC Range = GND to VRef Voltage VDD - Defines the microcontrollers power supply pin as the max reference, VREF+ Pin - Dedicated pin on the microcontroller to allow for a variable reference voltage.
	Conversion speed
Clock setting to select how fast the ADC peripheral will perform an ADC conversion. The FRC setting is based on a RC time base and so will vary with temperature and pressure. Other settings are generally based on divisions of the master clock.
	Acquisition cycles
Number of micro seconds to wait for the ADC input to charge before starting the analogue sample.
	Simulation
	Enable Interrupt
	Interrupt Macro

Component Source Code

Please click here to download the component source project: FC_Comp_Source_TouchScreen_Resistive.fcfx

Please click here to view the component source code (Beta): FC_Comp_Source_TouchScreen_Resistive.fcfx