mirror of
https://github.com/tinygo-org/drivers.git
synced 2026-07-26 10:38:41 +00:00
Adding driver for four-wire resistive touchscreen (#118)
* resistive: Adding driver for four-wire resistive touchscreen, as used on the Adafruit PyPortal.
This commit is contained in:
BCG
Ron Evans
@@ -85,6 +85,10 @@ smoke-test:
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@md5sum ./build/test.hex
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tinygo build -size short -o ./build/test.hex -target=circuitplay-express ./examples/thermistor/main.go
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@md5sum ./build/test.hex
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tinygo build -size short -o ./build/test.hex -target=pyportal ./examples/touch/resistive/fourwire/main.go
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@md5sum ./build/test.hex
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tinygo build -size short -o ./build/test.hex -target=pyportal ./examples/touch/resistive/pyportal_touchpaint/main.go
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@md5sum ./build/test.hex
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tinygo build -size short -o ./build/test.hex -target=itsybitsy-m0 ./examples/vl53l1x/main.go
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@md5sum ./build/test.hex
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tinygo build -size short -o ./build/test.hex -target=microbit ./examples/waveshare-epd/epd2in13/main.go
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@@ -84,6 +84,7 @@ The following 37 devices are supported.
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| [MMA8653 accelerometer](https://www.nxp.com/docs/en/data-sheet/MMA8653FC.pdf) | I2C |
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| [MPU6050 accelerometer/gyroscope](https://store.invensense.com/datasheets/invensense/MPU-6050_DataSheet_V3%204.pdf) | I2C |
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| [PCD8544 display](http://eia.udg.edu/~forest/PCD8544_1.pdf) | SPI |
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| [Resistive Touchscreen (4-wire)](http://ww1.microchip.com/downloads/en/Appnotes/doc8091.pdf) | GPIO |
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| [Shift register](https://en.wikipedia.org/wiki/Shift_register#Parallel-in_serial-out_\(PISO\)) | GPIO |
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| [SHT3x Digital Humidity Sensor](https://www.sensirion.com/fileadmin/user_upload/customers/sensirion/Dokumente/0_Datasheets/Humidity/Sensirion_Humidity_Sensors_SHT3x_Datasheet_digital.pdf) | I2C |
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| [SSD1306 OLED display](https://cdn-shop.adafruit.com/datasheets/SSD1306.pdf) | I2C / SPI |
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@@ -0,0 +1,80 @@
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// demo of 4-wire touchscreen as described in app note:
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// http://ww1.microchip.com/downloads/en/Appnotes/doc8091.pdf
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package main
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import (
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"machine"
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"math"
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"tinygo.org/x/drivers/touch"
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"tinygo.org/x/drivers/touch/resistive"
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)
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var (
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resistiveTouch = new(resistive.FourWire)
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)
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const (
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Xmin = 750
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Xmax = 325
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Ymin = 840
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Ymax = 240
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)
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func main() {
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// configure touchscreen
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machine.InitADC()
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resistiveTouch.Configure(&resistive.FourWireConfig{
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YP: machine.TOUCH_YD, // y+
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YM: machine.TOUCH_YU, // y-
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XP: machine.TOUCH_XR, // x+
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XM: machine.TOUCH_XL, // x-
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})
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last := touch.Point{}
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// loop and poll for touches, including performing debouncing
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debounce := 0
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for {
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point := resistiveTouch.ReadTouchPoint()
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touch := touch.Point{}
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if point.Z>>6 > 100 {
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touch.X = mapval(point.X>>6, Xmin, Xmax, 0, 240)
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touch.Y = mapval(point.Y>>6, Ymin, Ymax, 0, 320)
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touch.Z = point.Z >> 6 / 100
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} else {
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touch.X = 0
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touch.Y = 0
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touch.Z = 0
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}
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if last.Z != touch.Z {
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debounce = 0
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last = touch
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} else if math.Abs(float64(touch.X-last.X)) > 4 ||
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math.Abs(float64(touch.Y-last.Y)) > 4 {
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debounce = 0
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last = touch
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} else if debounce > 1 {
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debounce = 0
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HandleTouch(last)
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} else if touch.Z > 0 {
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debounce++
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} else {
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last = touch
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debounce = 0
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}
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}
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}
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// based on Arduino's "map" function
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func mapval(x int, inMin int, inMax int, outMin int, outMax int) int {
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return (x-inMin)*(outMax-outMin)/(inMax-inMin) + outMin
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}
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func HandleTouch(touch touch.Point) {
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println("touch point:", touch.X, touch.Y, touch.Z)
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}
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@@ -0,0 +1,185 @@
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package main
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import (
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"image/color"
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"machine"
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"math"
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"tinygo.org/x/drivers/ili9341"
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"tinygo.org/x/drivers/touch"
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"tinygo.org/x/drivers/touch/resistive"
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)
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var (
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resistiveTouch = &resistive.FourWire{}
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display = ili9341.NewParallel(
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machine.LCD_DATA0,
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machine.TFT_WR,
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machine.TFT_DC,
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machine.TFT_CS,
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machine.TFT_RESET,
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machine.TFT_RD,
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)
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white = color.RGBA{255, 255, 255, 255}
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black = color.RGBA{0, 0, 0, 255}
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red = color.RGBA{255, 0, 0, 255}
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green = color.RGBA{0, 255, 0, 255}
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blue = color.RGBA{0, 0, 255, 255}
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magenta = color.RGBA{255, 0, 255, 255}
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yellow = color.RGBA{255, 255, 0, 255}
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cyan = color.RGBA{0, 255, 255, 255}
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oldColor color.RGBA
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currentColor color.RGBA
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)
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const (
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penRadius = 3
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boxSize = 30
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Xmin = 750
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Xmax = 325
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Ymin = 840
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Ymax = 240
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)
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func main() {
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// configure backlight
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machine.TFT_BACKLIGHT.Configure(machine.PinConfig{machine.PinOutput})
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// configure touchscreen
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machine.InitADC()
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resistiveTouch.Configure(&resistive.FourWireConfig{
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YP: machine.TOUCH_YD,
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YM: machine.TOUCH_YU,
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XP: machine.TOUCH_XR,
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XM: machine.TOUCH_XL,
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})
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// configure display
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display.Configure(ili9341.Config{})
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// fill the background and activate the backlight
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width, height := display.Size()
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display.FillRectangle(0, 0, width, height, black)
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machine.TFT_BACKLIGHT.High()
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// make color selection boxes
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display.FillRectangle(0, 0, boxSize, boxSize, red)
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display.FillRectangle(boxSize, 0, boxSize, boxSize, yellow)
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display.FillRectangle(boxSize*2, 0, boxSize, boxSize, green)
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display.FillRectangle(boxSize*3, 0, boxSize, boxSize, cyan)
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display.FillRectangle(boxSize*4, 0, boxSize, boxSize, blue)
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display.FillRectangle(boxSize*5, 0, boxSize, boxSize, magenta)
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display.FillRectangle(boxSize*6, 0, boxSize, boxSize, black)
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display.FillRectangle(boxSize*7, 0, boxSize, boxSize, white)
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// set the initial color to red and draw a box to highlight it
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oldColor = red
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currentColor = red
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display.DrawRectangle(0, 0, boxSize, boxSize, white)
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last := touch.Point{}
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// loop and poll for touches, including performing debouncing
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debounce := 0
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for {
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point := resistiveTouch.ReadTouchPoint()
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touch := touch.Point{}
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if point.Z>>6 > 100 {
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rawX := mapval(point.X>>6, Xmin, Xmax, 0, 240)
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rawY := mapval(point.Y>>6, Ymin, Ymax, 0, 320)
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touch.X = rawX
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touch.Y = rawY
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touch.Z = 1
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} else {
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touch.X = 0
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touch.Y = 0
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touch.Z = 0
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}
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if last.Z != touch.Z {
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debounce = 0
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last = touch
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} else if math.Abs(float64(touch.X-last.X)) > 4 ||
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math.Abs(float64(touch.Y-last.Y)) > 4 {
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debounce = 0
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last = touch
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} else if debounce > 1 {
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debounce = 0
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HandleTouch(last)
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} else if touch.Z > 0 {
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debounce++
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} else {
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last = touch
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debounce = 0
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}
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}
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}
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// based on Arduino's "map" function
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func mapval(x int, inMin int, inMax int, outMin int, outMax int) int {
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return (x-inMin)*(outMax-outMin)/(inMax-inMin) + outMin
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}
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func HandleTouch(touch touch.Point) {
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if int16(touch.Y) < boxSize {
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oldColor = currentColor
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x := int16(touch.X)
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switch {
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case x < boxSize:
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currentColor = red
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case x < boxSize*2:
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currentColor = yellow
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case x < boxSize*3:
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currentColor = green
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case x < boxSize*4:
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currentColor = cyan
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case x < boxSize*5:
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currentColor = blue
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case x < boxSize*6:
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currentColor = magenta
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case x < boxSize*7:
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currentColor = black
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case x < boxSize*8:
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currentColor = white
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}
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if oldColor == currentColor {
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return
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}
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display.DrawRectangle((x/boxSize)*boxSize, 0, boxSize, boxSize, white)
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switch oldColor {
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case red:
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x = 0
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case yellow:
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x = boxSize
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case green:
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x = boxSize * 2
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case cyan:
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x = boxSize * 3
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case blue:
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x = boxSize * 4
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case magenta:
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x = boxSize * 5
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case black:
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x = boxSize * 6
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case white:
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x = boxSize * 7
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}
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display.FillRectangle(int16(x), 0, boxSize, boxSize, oldColor)
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}
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if (int16(touch.Y) - penRadius) > boxSize {
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display.FillRectangle(
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int16(touch.X), int16(touch.Y), penRadius*2, penRadius*2, currentColor)
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}
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}
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@@ -0,0 +1,17 @@
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package touch
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// Pointer is a device that is capable of reading a single touch point
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type Pointer interface {
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ReadTouchPoint() Point
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}
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// Point represents the result of reading a single touch point from a screen.
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// X and Y are the horizontal and vertical coordinates of the touch, while Z
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// represents the touch pressure. In general, client code will want to inspect
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// the value of Z to see if it is above some threshold to determine if a touch
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// is detected at all.
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type Point struct {
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X int
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Y int
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Z int
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}
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@@ -0,0 +1,124 @@
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package resistive
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import (
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"machine"
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"tinygo.org/x/drivers/touch"
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)
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// FourWire represents a resistive touchscreen with a four-wire interface as
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// described in http://ww1.microchip.com/downloads/en/Appnotes/doc8091.pdf
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type FourWire struct {
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yp machine.ADC
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ym machine.ADC
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xp machine.ADC
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xm machine.ADC
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readSamples int
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}
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// FourWireConfig is passed to the Configure method. All of the pins must be
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// specified for this to be a valid configuration. ReadSamples is optional, and
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// if not set with default to 2.
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type FourWireConfig struct {
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// Y+ pin, must be capable of analog reads
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YP machine.Pin
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// Y- pin, must be capable of analog reads
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YM machine.Pin
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// X+ pin, must be capable of analog reads
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XP machine.Pin
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// X- pin, must be capable of analog reads
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XM machine.Pin
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// If set, each call to ReadTouchPoint() will sample the X, Y, and Z values
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// and average them. This can help smooth out spurious readings, for example
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// ones that result from the capacitance of a TFT under the touchscreen
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ReadSamples int
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}
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// Configure should be called once before starting to read the device
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func (res *FourWire) Configure(config *FourWireConfig) error {
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res.yp = machine.ADC{Pin: config.YP}
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res.ym = machine.ADC{Pin: config.YM}
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res.xp = machine.ADC{Pin: config.XP}
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res.xm = machine.ADC{Pin: config.XM}
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if config.ReadSamples < 1 {
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res.readSamples = 2
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} else {
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res.readSamples = config.ReadSamples
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}
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return nil
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}
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// ReadTouchPoint reads a single touch.Point from the device. If the device
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// was configured with ReadSamples > 1, each value will be sampled that many
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// times and averaged to smooth over spurious results of the analog reads.
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func (res *FourWire) ReadTouchPoint() (p touch.Point) {
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p.X = int(sample(res.ReadX, res.readSamples))
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p.Y = int(sample(res.ReadY, res.readSamples))
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p.Z = int(sample(res.ReadZ, res.readSamples))
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return
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}
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// sample the results of the provided function and average the results
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func sample(fn func() uint16, numSamples int) (v uint16) {
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sum := 0
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for n := 0; n < numSamples; n++ {
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sum += int(fn())
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}
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return uint16(sum / numSamples)
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}
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// ReadX reads the "raw" X-value on a 16-bit scale without multiple sampling
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func (res *FourWire) ReadX() uint16 {
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res.ym.Pin.Configure(machine.PinConfig{Mode: machine.PinInputPulldown})
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res.xp.Pin.Configure(machine.PinConfig{Mode: machine.PinOutput})
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res.xp.Pin.High()
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res.xm.Pin.Configure(machine.PinConfig{Mode: machine.PinOutput})
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res.xm.Pin.Low()
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res.yp.Configure()
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return 0xFFFF - res.yp.Get()
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}
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// ReadY reads the "raw" Y-value on a 16-bit scale without multiple sampling
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func (res *FourWire) ReadY() uint16 {
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res.xm.Pin.Configure(machine.PinConfig{Mode: machine.PinInputPulldown})
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res.yp.Pin.Configure(machine.PinConfig{Mode: machine.PinOutput})
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res.yp.Pin.High()
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res.ym.Pin.Configure(machine.PinConfig{Mode: machine.PinOutput})
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res.ym.Pin.Low()
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res.xp.Configure()
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return 0xFFFF - res.xp.Get()
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}
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// ReadZ reads the "raw" Z-value on a 16-bit scale without multiple sampling
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func (res *FourWire) ReadZ() uint16 {
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res.xp.Pin.Configure(machine.PinConfig{Mode: machine.PinOutput})
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res.xp.Pin.Low()
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res.ym.Pin.Configure(machine.PinConfig{Mode: machine.PinOutput})
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res.ym.Pin.High()
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res.xm.Configure()
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res.yp.Configure()
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z1 := res.xm.Get()
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z2 := res.yp.Get()
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return 0xFFFF - (z2 - z1)
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}
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