fix the init sequence and drawing

ssd1306/ssd1306.go

@@ -40,56 +40,43 @@ type OLED struct {
 
 var initSeq = []byte{
 	0xae,
-	0x00,
-	0x10,
-	0x40,
-	0x81,
-	0xcf,
-	0xa1,
-	0xc8,
-	0xa6,
-	0xa4,
-	0xa8,
-	0x3f,
-	0xd3,
-	0x00,
-	0xd5,
-	0x80,
-	0xd9,
-	0xf1,
-	0xda,
-	0x12,
-	0xdb,
-	0x40,
-	0x20,
-	0x00,
-	0x8d,
-	0x14,
-	0xa5,
+	0x00 | 0x00, // row offset
+	0x10 | 0x00, // column offset
+	0xd5, 0x40,
+	0xa8, ssd1306_LCDHEIGHT - 1,
+	0xd3, 0x00, // set display offset to no offset
+	0x40 | 0,
+	0x8d, 0x14,
+	0x20, 0x0,
+
+	0xA0 | 0x1,
+	0xC8,
+	0xda, 0x12,
+	0x81, 0x9f, // set contast
+	0x9d, 0xf1,
+	0xdb, 0x40,
+	0xa4, 0xa6,
+
+	0x2E,
 	0xaf,
 }
 
 // Open opens an SSD1306 OLED display. Once not in use, it needs to
 // be close by calling Close.
 // The default width is 128, height is 64 if zero values are given.
-func Open(o driver.Opener, width, height int) (*OLED, error) {
-	if width == 0 {
-		width = ssd1306_LCDWIDTH
-	}
-	if height == 0 {
-		height = ssd1306_LCDHEIGHT
-	}
+func Open(o driver.Opener) (*OLED, error) {
+	w := ssd1306_LCDWIDTH
+	h := ssd1306_LCDHEIGHT
 	dev, err := i2c.Open(o)
 	if err != nil {
 		return nil, err
 	}
 	if err := dev.Write(initSeq); err != nil {
-		dev.Close()
 		return nil, err
 	}
-	buf := make([]byte, width*(height/8)+1)
+	buf := make([]byte, w*(h/8)+1)
 	buf[0] = 0x40 // start frame of pixel data
-	return &OLED{dev: dev, w: width, h: height, buf: buf}, nil
+	return &OLED{dev: dev, w: w, h: h, buf: buf}, nil
 }
 
 // On turns on the display if it is off.
@@ -104,15 +91,13 @@ func (o *OLED) Off() error {
 
 // Clear clears the entire display.
 func (o *OLED) Clear() error {
-	for i := 0; i < len(o.buf); i++ {
-		o.buf[0] = 0
+	for i := 1; i < len(o.buf); i++ {
+		o.buf[i] = 0
 	}
-	return o.drawBuf(0, o.buf)
+	return o.Draw()
 }
 
-// DrawPixel draws a pixel on the OLED display.
-// v can either be 0 or 1.
-func (o *OLED) DrawPixel(x, y int, v byte) error {
+func (o *OLED) SetPixel(x, y int, v byte) error {
 	if x >= o.w || y >= o.h {
 		return fmt.Errorf("(x=%v, y=%v) is out of bounds on this %vx%v display", x, y, o.w, o.h)
 	}
@@ -121,22 +106,22 @@ func (o *OLED) DrawPixel(x, y int, v byte) error {
 	}
 	i := x + (y/8)*o.w + 1
 	o.buf[i] = o.buf[i] | v<<uint((y%8))
-	return o.drawBuf(x, o.buf)
+	return nil
 }
 
 // DrawImage draws an image on the OLED display starting from x, y.
-func (o *OLED) DrawImage(x, y int, img image.Image) error {
+func (o *OLED) DrawImage(x int, img image.Image) error {
 	panic("not implemented")
 }
 
-func (o *OLED) drawBuf(x int, buf []byte) error {
-	if err := o.dev.Write([]byte{0xa4}); err != nil { // the write mode
-		return err
-	}
-	if err := o.dev.Write([]byte{0x40 | byte(x)}); err != nil { //set the start line to x
+func (o *OLED) Draw() error {
+	if err := o.dev.Write([]byte{
+		0x21, 0, ssd1306_LCDWIDTH - 1,
+		0x22, 0, 7,
+	}); err != nil { // the write mode
 		return err
 	}
-	return o.dev.Write(buf)
+	return o.dev.Write(o.buf)
 }
 
 // StartScroll starts scrolling in the horizontal direction starting from