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deadprogram
125 lines
3.3 KiB
Go
125 lines
3.3 KiB
Go
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(machine.ADCConfig{})
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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(machine.ADCConfig{})
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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(machine.ADCConfig{})
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res.yp.Configure(machine.ADCConfig{})
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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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