218 lines
6.5 KiB
C
218 lines
6.5 KiB
C
// Module for xpt2046
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// by Starofall, F.J. Exoo
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// used source code from:
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// - https://github.com/spapadim/XPT2046/
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// - https://github.com/PaulStoffregen/XPT2046_Touchscreen/
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#include "module.h"
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#include "lauxlib.h"
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#include "platform.h"
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// Hardware specific values
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static const uint16_t CAL_MARGIN = 0; // Set to 0: up to the application
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static const uint8_t CTRL_LO_DFR = 0b0011;
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static const uint8_t CTRL_LO_SER = 0b0100;
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static const uint8_t CTRL_HI_X = 0b1001 << 4;
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static const uint8_t CTRL_HI_Y = 0b1101 << 4;
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static const uint16_t ADC_MAX = 0x0fff; // 12 bits
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// Runtime variables
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static uint16_t _width, _height;
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static uint8_t _cs_pin, _irq_pin;
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static int32_t _cal_dx, _cal_dy, _cal_dvi, _cal_dvj;
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static uint16_t _cal_vi1, _cal_vj1;
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// Average pair with least distance between each
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static int16_t besttwoavg( int16_t x , int16_t y , int16_t z ) {
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int16_t da, db, dc;
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int16_t reta = 0;
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if ( x > y ) da = x - y; else da = y - x;
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if ( x > z ) db = x - z; else db = z - x;
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if ( z > y ) dc = z - y; else dc = y - z;
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if ( da <= db && da <= dc ) reta = (x + y) >> 1;
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else if ( db <= da && db <= dc ) reta = (x + z) >> 1;
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else reta = (y + z) >> 1;
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return reta;
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}
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// Checks if the irq_pin is down
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static int isTouching() {
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return (platform_gpio_read(_irq_pin) == 0);
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}
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// transfer 16 bits from the touch display - returns the recived uint16_t
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static uint16_t transfer16(uint16_t _data) {
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union { uint16_t val; struct { uint8_t lsb; uint8_t msb; }; } t;
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t.val = _data;
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t.msb = platform_spi_send_recv(1, 8, t.msb);
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t.lsb = platform_spi_send_recv(1, 8, t.lsb);
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return t.val;
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}
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// reads the value from the touch panel
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static uint16_t _readLoop(uint8_t ctrl, uint8_t max_samples) {
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uint16_t prev = 0xffff, cur = 0xffff;
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uint8_t i = 0;
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do {
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prev = cur;
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cur = platform_spi_send_recv(1, 8 , 0);
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cur = (cur << 4) | (platform_spi_send_recv(1, 8 , ctrl) >> 4); // 16 clocks -> 12-bits (zero-padded at end)
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} while ((prev != cur) && (++i < max_samples));
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return cur;
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}
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// Returns the raw position information
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static void getRaw(uint16_t *vi, uint16_t *vj) {
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// Implementation based on TI Technical Note http://www.ti.com/lit/an/sbaa036/sbaa036.pdf
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// Disable interrupt: reading position generates false interrupt
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ETS_GPIO_INTR_DISABLE();
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platform_gpio_write(_cs_pin, PLATFORM_GPIO_LOW);
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platform_spi_send_recv(1, 8 , CTRL_HI_X | CTRL_LO_DFR); // Send first control int
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*vi = _readLoop(CTRL_HI_X | CTRL_LO_DFR, 255);
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*vj = _readLoop(CTRL_HI_Y | CTRL_LO_DFR, 255);
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// Turn off ADC by issuing one more read (throwaway)
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// This needs to be done, because PD=0b11 (needed for MODE_DFR) will disable PENIRQ
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platform_spi_send_recv(1, 8 , 0); // Maintain 16-clocks/conversion; _readLoop always ends after issuing a control int
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platform_spi_send_recv(1, 8 , CTRL_HI_Y | CTRL_LO_SER);
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transfer16(0); // Flush last read, just to be sure
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platform_gpio_write(_cs_pin, PLATFORM_GPIO_HIGH);
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// Clear interrupt status
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GPIO_REG_WRITE(GPIO_STATUS_W1TC_ADDRESS, BIT(pin_num[_irq_pin]));
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// Enable interrupt again
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ETS_GPIO_INTR_ENABLE();
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}
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// sets the calibration of the display
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static void setCalibration (uint16_t vi1, uint16_t vj1, uint16_t vi2, uint16_t vj2) {
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_cal_dx = _width - 2*CAL_MARGIN;
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_cal_dy = _height - 2*CAL_MARGIN;
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_cal_vi1 = (int32_t)vi1;
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_cal_vj1 = (int32_t)vj1;
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_cal_dvi = (int32_t)vi2 - vi1;
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_cal_dvj = (int32_t)vj2 - vj1;
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}
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// returns the position on the screen by also applying the calibration
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static void getPosition (uint16_t *x, uint16_t *y) {
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if (isTouching() == 0) {
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*x = *y = 0xffff;
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return;
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}
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uint16_t vi, vj;
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getRaw(&vi, &vj);
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// Map to (un-rotated) display coordinates
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*x = (uint16_t)(_cal_dx * (vj - _cal_vj1) / _cal_dvj + CAL_MARGIN);
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if (*x > 0x7fff) *x = 0;
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*y = (uint16_t)(_cal_dy * (vi - _cal_vi1) / _cal_dvi + CAL_MARGIN);
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if (*y > 0x7fff) *y = 0;
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}
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// Lua: xpt2046.init(cspin, irqpin, height, width)
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static int xpt2046_init( lua_State* L ) {
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_cs_pin = luaL_checkinteger( L, 1 );
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_irq_pin = luaL_checkinteger( L, 2 );
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_height = luaL_checkinteger( L, 3 );
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_width = luaL_checkinteger( L, 4 );
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// set pins correct
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platform_gpio_mode(_cs_pin, PLATFORM_GPIO_OUTPUT, PLATFORM_GPIO_FLOAT );
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setCalibration(
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/*vi1=*/((int32_t)CAL_MARGIN) * ADC_MAX / _width,
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/*vj1=*/((int32_t)CAL_MARGIN) * ADC_MAX / _height,
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/*vi2=*/((int32_t)_width - CAL_MARGIN) * ADC_MAX / _width,
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/*vj2=*/((int32_t)_height - CAL_MARGIN) * ADC_MAX / _height
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);
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// assume spi was inited before with a clockDiv of >=16
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// as higher spi clock speed produced inaccurate results
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// do first powerdown
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platform_gpio_write(_cs_pin, PLATFORM_GPIO_LOW);
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// Issue a throw-away read, with power-down enabled (PD{1,0} == 0b00)
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// Otherwise, ADC is disabled
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platform_spi_send_recv(1, 8, CTRL_HI_Y | CTRL_LO_SER);
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transfer16(0); // Flush, just to be sure
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platform_gpio_write(_cs_pin, PLATFORM_GPIO_HIGH);
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return 0;
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}
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// Lua: xpt2046.isTouched()
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static int xpt2046_isTouched( lua_State* L ) {
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lua_pushboolean( L, isTouching());
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return 1;
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}
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// Lua: xpt2046.setCalibration(a,b,c,d)
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static int xpt2046_setCalibration( lua_State* L ) {
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int32_t a = luaL_checkinteger( L, 1 );
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int32_t b = luaL_checkinteger( L, 2 );
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int32_t c = luaL_checkinteger( L, 3 );
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int32_t d = luaL_checkinteger( L, 4 );
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setCalibration(a,b,c,d);
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return 0;
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}
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// Lua: xpt2046.xpt2046_getRaw()
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static int xpt2046_getRaw( lua_State* L ) {
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uint16_t x, y;
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getRaw(&x, &y);
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lua_pushinteger( L, x);
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lua_pushinteger( L, y);
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return 2;
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}
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// Lua: xpt2046.xpt2046_getPosition()
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static int xpt2046_getPosition( lua_State* L ) {
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uint16_t x, y;
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getPosition(&x, &y);
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lua_pushinteger( L, x);
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lua_pushinteger( L, y);
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return 2;
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}
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// Lua: xpt2046.xpt2046_getPositionAvg()
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static int xpt2046_getPositionAvg( lua_State* L ) {
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// Run three times
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uint16_t x1, y1, x2, y2, x3, y3;
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getPosition(&x1, &y1);
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getPosition(&x2, &y2);
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getPosition(&x3, &y3);
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// Average the two best results
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int16_t x = besttwoavg(x1,x2,x3);
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int16_t y = besttwoavg(y1,y2,y3);
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lua_pushinteger( L, x);
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lua_pushinteger( L, y);
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return 2;
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}
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// Module function map
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LROT_BEGIN(xpt2046, NULL, 0)
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LROT_FUNCENTRY( isTouched, xpt2046_isTouched )
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LROT_FUNCENTRY( getRaw, xpt2046_getRaw )
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LROT_FUNCENTRY( getPosition, xpt2046_getPosition )
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LROT_FUNCENTRY( getPositionAvg, xpt2046_getPositionAvg )
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LROT_FUNCENTRY( setCalibration, xpt2046_setCalibration )
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LROT_FUNCENTRY( init, xpt2046_init )
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LROT_END(xpt2046, NULL, 0)
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NODEMCU_MODULE(XPT2046, "xpt2046", xpt2046, NULL);
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