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epaper.go
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epaper.go
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package epaper
import (
"bytes"
"fmt"
"github.com/stianeikeland/go-rpio"
"math"
"math/rand"
"os"
"time"
)
const (
dcPin = rpio.Pin(25) // OUT 0 = command, 1 = data
resetPin = rpio.Pin(22) // OUT 0 = reset
busyPin = rpio.Pin(24) // IN 0 = busy
)
// setup gpio and SPI interface
func Setup() {
err := rpio.Open()
if err != nil {
fmt.Print(err)
os.Exit(1)
}
resetPin.Output()
dcPin.Output()
busyPin.Input()
busyPin.PullDown()
resetPin.High()
// SETUP SPI:
err = rpio.SpiBegin(rpio.Spi0)
// freq 128 divider - default
// chip select CE0 - default
// ce enable low - implicit
// mode 0 - implicit
// msb first - implicit
if err != nil {
fmt.Print(err)
os.Exit(2)
}
}
// teardown gpio and SPI interface
func Teardown() {
rpio.SpiEnd(rpio.Spi0)
rpio.Close()
}
var (
lut Lut
cmd Cmd
dim Dim
ink Ink
) // global vars holding used values, fill in with Use
func Use(e Module) {
lut = e.Lut
cmd = e.Cmd
dim = e.Dim
ink = e.Ink
}
func Init(update string) {
Reset()
SendCommand(cmd.DRIVER_OUTPUT_CONTROL)
SendData(
byte((dim.HEIGHT-1)&0xFF),
byte((dim.HEIGHT-1)>>8),
0x00, // GD = 0; SM = 0; TB = 0;
)
SendCommand(cmd.BOOSTER_SOFT_START_CONTROL)
// SendData(0xD7, 0xD6, 0x9D)
SendData(0xCF, 0xCE, 0x8D)
SendCommand(cmd.WRITE_VCOM_REGISTER)
SendData(0x7c) // VCOM 7C // 8a
SendCommand(cmd.SET_DUMMY_LINE_PERIOD)
SendData(0x1A) // 4 dummy lines per gate
SendCommand(cmd.SET_GATE_TIME)
SendData(0x08) // 2us per line
SendCommand(cmd.DATA_ENTRY_MODE_SETTING)
SendData(0x03) // X increment Y increment
if update == "partial" {
SetLut(lut.PARTIAL)
}
if update == "full" {
SetLut(lut.FULL)
}
}
func SendCommand(cmd byte) {
dcPin.Low()
rpio.SpiTransmit(cmd)
}
func SendData(data ...byte) {
dcPin.High()
rpio.SpiTransmit(data...)
}
func WaitUntilIdle() {
for busyPin.Read() == rpio.High { // doc say Low == busy, but it is the oposite
time.Sleep(time.Millisecond * 50)
}
}
func Reset() {
resetPin.Low()
time.Sleep(time.Millisecond * 100)
resetPin.High()
time.Sleep(time.Millisecond * 100)
}
func SetLut(lut []byte) {
SendCommand(cmd.WRITE_LUT_REGISTER)
SendData(lut...)
}
func Clear(color byte) {
h := dim.HEIGHT
w := dim.WIDTH
SetMemoryArea(0, 0, w-1, h-1)
SetMemoryPointer(0, 0)
SendCommand(cmd.WRITE_RAM)
/* send the color data */
var img = bytes.Repeat([]byte{color}, int(inBytes(w)*h))
SendData(img...)
SwapFrame()
}
func Randomize() {
h := dim.HEIGHT
w := dim.WIDTH
SetMemoryArea(0, 0, w-1, h-1)
SetMemoryPointer(0, 0)
SendCommand(cmd.WRITE_RAM)
/* send the color data */
var img = make([]byte, int(inBytes(w)*h))
for i := range img {
img[i] = byte(rand.Int())
}
SendData(img...)
SwapFrame()
}
// Will display bitmap
// if image is larger, it will be cropped
func Display(img []byte, x, y int, imgWidth, imgHeight uint) {
if len(img) < int(imgHeight*inBytes(imgWidth)) {
fmt.Print("bitmap too small")
return
}
/* x point must be the multiple of 8 or the last 3 bits will be ignored */
xEnd := uint(math.Min(
float64(x+int(imgWidth-1)),
float64(dim.WIDTH-1)),
)
yEnd := uint(math.Min(
float64(y+int(imgHeight-1)),
float64(dim.HEIGHT-1)),
)
xStart := uint(math.Max(float64(x), 0))
yStart := uint(math.Max(float64(y), 0))
SetMemoryArea(xStart, yStart, xEnd, yEnd)
SetMemoryPointer(xStart, yStart)
SendCommand(cmd.WRITE_RAM)
/* send the img data, line by line */
rowsToCrop := (yStart + imgHeight - dim.HEIGHT)
if y < 0 { // crop top
img = img[inBytes(imgWidth)*uint(-y):]
rowsToCrop -= uint(-y)
}
for len(img) > 0 && len(img) > int(inBytes(imgWidth)*rowsToCrop) {
if x >= 0 {
SendData(img[0:inBytes(xEnd-xStart)]...)
} else { // crop left part
SendData(img[inBytes(uint(-x)):inBytes(xEnd+uint(-x))]...)
}
img = img[inBytes(imgWidth):] // next line
}
SwapFrame()
}
// Will swap back frame with front frame and displays what's on it
func SwapFrame() {
SendCommand(cmd.DISPLAY_UPDATE_CONTROL_2)
SendData(0xC4)
SendCommand(cmd.MASTER_ACTIVATION)
SendCommand(cmd.TERMINATE_FRAME_READ_WRITE)
WaitUntilIdle()
}
func SetMemoryArea(x_start, y_start, x_end, y_end uint) {
SendCommand(cmd.SET_RAM_X_ADDRESS_START_END_POSITION)
/* x point must be the multiple of 8 or the last 3 bits will be ignored */
SendData(byte(x_start >> 3))
SendData(byte(x_end >> 3))
SendCommand(cmd.SET_RAM_Y_ADDRESS_START_END_POSITION)
SendData(byte(y_start))
SendData(byte(y_start >> 8))
SendData(byte(y_end))
SendData(byte(y_end >> 8))
WaitUntilIdle()
}
func SetMemoryPointer(x, y uint) {
SendCommand(cmd.SET_RAM_X_ADDRESS_COUNTER)
/* x point must be the multiple of 8 or the last 3 bits will be ignored */
SendData(byte(x >> 3))
SendCommand(cmd.SET_RAM_Y_ADDRESS_COUNTER)
SendData(byte(y))
SendData(byte(y >> 8))
WaitUntilIdle()
}
func Sleep() {
SendCommand(cmd.DEEP_SLEEP_MODE)
SendData(1)
// WaitUntilIdle()
}
// division by eight but round up
func inBytes(n uint) uint {
if n%8 == 0 {
return n / 8
} else {
return n/8 + 1
}
}