132 lines
3.7 KiB
Markdown
132 lines
3.7 KiB
Markdown
# XPT2046 Module
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| Since | Origin / Contributor | Maintainer | Source |
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| :----- | :-------------------- | :---------- | :------ |
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| 2017-03-09| [Starofall](https://github.com/nodemcu/nodemcu-firmware/pull/1242)/[Frank Exoo](https://github.com/FrankX0) | [Frank Exoo](https://github.com/FrankX0) | [xpt2046.c](../../app/modules/xpt2046.c)|
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XPT2046 is a touch controller used by several cheap displays - often in combination with the ILI9341 display controller.
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The module is built based on the libraries of [spapadim](https://github.com/spapadim/XPT2046/) and [PaulStoffregen](https://github.com/PaulStoffregen/XPT2046_Touchscreen).
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## xpt2046.init()
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Initiates the XPT2046 module to read touch values from the display. It is required to call [`spi.setup()`](spi.md#spisetup) before calling `xpt2046.init` (see example).
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As the ucg lib also requires [`spi.setup()`](spi.md#spisetup) to be called before it is important to only call it once in total and to activate `spi.FULLDUPLEX`.
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The `clock_div` used in [`spi.setup()`](spi.md#spisetup) should be 16 or higher, as lower values might produces inaccurate results.
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#### Syntax
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`xpt2046.init(cs_pin, irq_pin, height, width)`
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#### Parameters
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- `cs_pin` GPIO pin for cs
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- `irq_pin` GPIO pin for irq
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- `height` display height in pixel
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- `width` display width in pixel
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#### Returns
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`nil`
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#### Example
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```lua
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-- Setup spi with `clock_div` of 16 and spi.FULLDUPLEX
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spi.setup(1, spi.MASTER, spi.CPOL_LOW, spi.CPHA_LOW, 8, 16,spi.FULLDUPLEX)
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-- SETTING UP DISPLAY (using ucg module)
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local disp = ucg.ili9341_18x240x320_hw_spi(8, 4, 0)
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disp:begin(0)
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-- SETTING UP TOUCH
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xpt2046.init(2,1,320,240)
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xpt2046.setCalibration(198, 1776, 1762, 273)
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```
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## xpt2046.setCalibration()
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Sets the calibration of the display. Calibration values can be obtained by using [`xpt2046.getRaw()`](#xpt2046getraw) and read the values in the edges.
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#### Syntax
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`xpt2046.setCalibration(x1, y1, x2, y2)`
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#### Parameters
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- `x1` raw x value at top left
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- `y1` raw y value at top left
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- `x2` raw x value at bottom right
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- `y2` raw y value at bottom right
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#### Returns
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`nil`
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## xpt2046.isTouched()
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Checks if the touch panel is touched.
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#### Syntax
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`xpt2046.isTouched()`
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#### Returns
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`true` if the display is touched, else `false`
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#### Example
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```lua
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if(xpt2046.isTouched()) then
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local x, y = xpt2046.getPosition()
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print(x .. "-" .. y)
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end
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```
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## xpt2046.getPosition()
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Returns the position the display is touched using the calibration values and given width and height.
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Can be used in an interrupt pin callback to return the coordinates when the touch screen is touched.
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#### Syntax
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`xpt2046.getPosition()`
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#### Returns
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returns both the x and the y position.
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#### Example
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```lua
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-- Setup spi with `clock_div` of 16 and spi.FULLDUPLEX
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spi.setup(1, spi.MASTER, spi.CPOL_LOW, spi.CPHA_LOW, 8, 16,spi.FULLDUPLEX)
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-- SETTING UP TOUCH
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cs_pin = 2 -- GPIO4
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irq_pin = 3 -- GPIO0
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height = 240
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width = 320
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xpt2046.init(cs_pin, irq_pin, width, height)
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xpt2046.setCalibration(198, 1776, 1762, 273)
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gpio.mode(irq_pin,gpio.INT,gpio.PULLUP)
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gpio.trig(irq_pin, "down", function()
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print(xpt2046.getPosition())
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end)
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```
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## xpt2046.getPositionAvg()
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To create better measurements this function reads the position three times and averages the two positions with the least distance.
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#### Syntax
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`xpt2046.getPositionAvg()`
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#### Returns
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returns both the x and the y position.
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#### Example
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```lua
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local x, y = xpt2046.getPositionAvg()
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print(x .. "-" .. y)
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```
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## xpt2046.getRaw()
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Reads the raw value from the display. Useful for debugging and custom conversions.
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#### Syntax
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`xpt2046.getRaw()`
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#### Returns
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returns both the x and the y position as a raw value.
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#### Example
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```lua
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local rawX, rawY = xpt2046.getRaw()
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print(rawX .. "-" .. rawY)
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```
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