Touch_Read
Syntax
Assignment Variable = Touch_Read
Overview
Get the X and Y pixel coordinates from the graphic LCD's resistive touch membrane.
Parameters
None Assignment Variable can be any valid variable type and holds 1 if the touch screen membrane has been touched within its bounds. Two variables are loaded with the X and Y pixel coordinates. These are: Touch_Xpos holds the X position of the touch (0 to 239) Touch_Ypos holds the Y position of the touch (0 to 319)
Example
' Demonstrate the Touch_Read command
'
Device = 24HJ128GP502 ' Select the device to compile for
Declare Xtal = 79.23
'
' Setup the ADS7846 touch screen chip's pins
'
Declare Touch_DINPin = PORTB.13 ' Connect to the ADS7846 DIN pin
Declare Touch_DOUTPin = PORTB.12 ' Connect to the ADS7846 DOUT pin
Declare Touch_CLKPin = PORTB.11 ' Connect to the ADS7846 CLK pin
Declare Touch_CSPin = PORTB.9 ' Connect to the ADS7846 CS pin
Include "TouchScreen.inc" ' Load the touch screen routines into the program
' Configure the internal oscillator to operate the device at 79.23MHz
'
PLL_Setup(43, 2, 2, $0300)
Do
If Touch_Active = 1 Then ' Has the LCD been touched?
If Touch_Read = 1 Then ' Is the touch within bounds?
HRSOut "X Touch = ", Dec Touch_Xpos, 13
HRSOut "Y Touch = ", Dec Touch_Ypos, 13
DelayMs 200
EndIf
EndIf
Loop
'-------------------------------------------------------------------------
' Configure for internal 7.37MHz oscillator with PLL
' OSC pins are general purpose I/O
'
Config FBS = BWRP_WRPROTECT_OFF, BSS_NO_FLASH, BSS_NO_BOOT_CODE
Config FSS = SWRP_WRPROTECT_OFF, SSS_NO_FLASH, RSS_NO_SEC_RAM
Config FGS = GWRP_OFF, GCP_OFF
Config FOSCSEL = FNOSC_FRCPLL, IESO_ON
Config FOSC = POSCMD_NONE, OSCIOFNC_ON, IOL1WAY_OFF, FCKSM_CSDCMD
Config FWDT = WDTPOST_PS256, WINDIS_OFF, FWDTEN_OFF
Config FPOR = FPWRT_PWR128, ALTI2C_OFF
Config FICD = ICS_PGD1, JTAGEN_OFF
Notes.
The touch screen commands used by the compiler are for use with an ADS7846 touch screen controller device. This device uses an SPI interface and connects to a 4-wire resistive touch screen membrane to give X and Y coordinates, as well as touch pressure.
The routines must be incorporated into the BASIC program by use of an include file named "TouchScreen.inc". This is written in Positron16 BASIC so that modifications or improvements are easy. It also exposes how the touch screen is interfaced with.
See Also. Touch_Active, Touch_HotSpot
