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microbitmatrix: add support for brightness of led pixels

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Inspired by brightness levels in micro:bit MicroPython
This commit is contained in:
Lucas Bremgartner
2022-10-10 23:56:49 +02:00
committed by Ron Evans
parent 8a39bb7aae
commit 89770a7d05
3 changed files with 93 additions and 15 deletions
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microbitmatrix/microbitmatrix-v1.go
+1 -1
View File
@@ -52,7 +52,7 @@ const (
type Device struct {
pin [ledCols + ledRows]machine.Pin
buffer [ledRows][ledCols]bool
buffer [ledRows][ledCols]int8
rotation uint8
}
microbitmatrix/microbitmatrix-v2.go
+1 -1
View File
@@ -52,7 +52,7 @@ const (
type Device struct {
pin [ledCols + ledRows]machine.Pin
buffer [ledRows][ledCols]bool
buffer [ledRows][ledCols]int8
rotation uint8
}
microbitmatrix/microbitmatrix.go
+91 -13
View File
@@ -43,20 +43,53 @@ func (d *Device) Configure(cfg Config) {
//
// Valid values for rotation:
//
// 0: regular orientation, (0 degree rotation)
// 1: 90 degree rotation clock wise
// 2: 180 degree rotation clock wise
// 3: 270 degree rotation clock wise
// 0: regular orientation, (0 degree rotation)
// 1: 90 degree rotation clock wise
// 2: 180 degree rotation clock wise
// 3: 270 degree rotation clock wise
func (d *Device) SetRotation(rotation uint8) {
d.rotation = rotation % 4
}
// Source:
// https://github.com/bbcmicrobit/micropython/blob/1252f887ddc790676bf9314a136bd17650b9c36c/source/microbit/microbitdisplay.cpp#L282
var renderTimings = []time.Duration{
0, // Bright, Ticks Duration, Relative power
2, // 1, 2, 32µs, inf
2, // 2, 4, 64µs, 200%
4, // 3, 8, 128µs, 200%
7, // 4, 15, 240µs, 187%
13, // 5, 28, 448µs, 187%
25, // 6, 53, 848µs, 189%
49, // 7, 102, 1632µs, 192%
97, // 8, 199, 3184µs, 195%
}
// Source:
// https://github.com/bbcmicrobit/micropython/blob/1252f887ddc790676bf9314a136bd17650b9c36c/source/microbit/microbitdisplay.cpp#L368
const tickDuration = 16 * time.Microsecond
const (
rowIdx = 0
colIdx = 1
)
// SetPixel modifies the internal buffer in a single pixel.
//
// The alpha channel of the RGBA is used to control the brightness of the LED
// in 9 different levels.
//
// alpha channel, brightness level
// 0 - 27, 9 (no transparency = highest brightness)
// 28 - 55, 8
// 56 - 83, 7
// 84 - 111, 6
// 112 - 139, 5
// 140 - 167, 4
// 168 - 195, 3
// 196 - 223, 2
// 224 - 251, 1 (very high transparency = lowest brightness)
// 252 - 255, 0 (full transparency = off)
func (d *Device) SetPixel(x int16, y int16, c color.RGBA) {
if x < 0 || x >= 5 || y < 0 || y >= 5 {
return
@@ -64,12 +97,37 @@ func (d *Device) SetPixel(x int16, y int16, c color.RGBA) {
col := x
row := y
if c.R != 0 || c.G != 0 || c.B != 0 {
d.buffer[matrixRotations[d.rotation][row][col][rowIdx]][matrixRotations[d.rotation][row][col][colIdx]] = true
d.buffer[matrixRotations[d.rotation][row][col][rowIdx]][matrixRotations[d.rotation][row][col][colIdx]] = brightness(c.A)
} else {
d.buffer[matrixRotations[d.rotation][row][col][rowIdx]][matrixRotations[d.rotation][row][col][colIdx]] = false
d.buffer[matrixRotations[d.rotation][row][col][rowIdx]][matrixRotations[d.rotation][row][col][colIdx]] = 0
}
}
const (
brightnessLevels = 9
brightnessDivider = int8(255 / brightnessLevels)
)
var (
Brightness0 = color.RGBA{R: 0, G: 0, B: 0, A: 0}
Brightness1 = color.RGBA{R: 255, G: 255, B: 255, A: 255 - uint8(brightnessDivider)*1}
Brightness2 = color.RGBA{R: 255, G: 255, B: 255, A: 255 - uint8(brightnessDivider)*2}
Brightness3 = color.RGBA{R: 255, G: 255, B: 255, A: 255 - uint8(brightnessDivider)*3}
Brightness4 = color.RGBA{R: 255, G: 255, B: 255, A: 255 - uint8(brightnessDivider)*4}
Brightness5 = color.RGBA{R: 255, G: 255, B: 255, A: 255 - uint8(brightnessDivider)*5}
Brightness6 = color.RGBA{R: 255, G: 255, B: 255, A: 255 - uint8(brightnessDivider)*6}
Brightness7 = color.RGBA{R: 255, G: 255, B: 255, A: 255 - uint8(brightnessDivider)*7}
Brightness8 = color.RGBA{R: 255, G: 255, B: 255, A: 255 - uint8(brightnessDivider)*8}
Brightness9 = color.RGBA{R: 255, G: 255, B: 255, A: 255 - uint8(brightnessDivider)*9}
BrightnessOff = Brightness0
BrightnessFull = Brightness9
)
func brightness(alpha uint8) int8 {
return brightnessLevels - int8(alpha/uint8(brightnessDivider))
}
// GetPixel returns if the specific pixels is enabled.
func (d *Device) GetPixel(x int16, y int16) bool {
if x < 0 || x >= 5 || y < 0 || y >= 5 {
@@ -77,26 +135,46 @@ func (d *Device) GetPixel(x int16, y int16) bool {
}
col := x
row := y
return d.buffer[matrixRotations[d.rotation][row][col][rowIdx]][matrixRotations[d.rotation][row][col][colIdx]]
return d.buffer[matrixRotations[d.rotation][row][col][rowIdx]][matrixRotations[d.rotation][row][col][colIdx]] > 0
}
const displayRefreshDelay = 8 * time.Millisecond
// Display sends the buffer (if any) to the screen.
func (d *Device) Display() error {
var displayBuffer [ledRows][ledCols]int8
for row := 0; row < ledRows; row++ {
for col := 0; col < ledCols; col++ {
displayBuffer[row][col] = d.buffer[row][col]
}
}
for row := 0; row < ledRows; row++ {
d.DisableAll()
d.pin[ledCols+row].Low()
d.pin[ledCols+row].High()
for col := 0; col < ledCols; col++ {
if d.buffer[row][col] {
d.pin[col].High()
} else {
if displayBuffer[row][col] > 0 {
d.pin[col].Low()
}
}
time.Sleep(time.Millisecond * 4)
then := time.Now()
var offset time.Duration = 0
for _, ticks := range renderTimings {
for time.Since(then).Nanoseconds() < int64(ticks*tickDuration+offset) {
time.Sleep(offset / 10)
}
offset += ticks + tickDuration
for col := 0; col < ledCols; col++ {
displayBuffer[row][col]--
if displayBuffer[row][col] <= 0 {
d.pin[col].High()
}
}
}
}
time.Sleep(displayRefreshDelay)
return nil
}
@@ -104,7 +182,7 @@ func (d *Device) Display() error {
func (d *Device) ClearDisplay() {
for row := 0; row < ledRows; row++ {
for col := 0; col < ledCols; col++ {
d.buffer[row][col] = false
d.buffer[row][col] = 0
}
}
}