unicornpaint

A web-based painting app for raspberry PI and pimoroni Unicorn Hat HD
Log | Files | Refs | README

RealUnicorn.go (1358B)

      1 // +build linux,arm linux,arm64
      2 
      3 package unicorn
      4 
      5 import (
      6 	"log"
      7 	"os"
      8 	"os/signal"
      9 	"syscall"
     10 
     11 	"github.com/ecc1/spi"
     12 )
     13 
     14 type RealUnicorn struct {
     15 	BaseUnicorn
     16 	device *spi.Device
     17 }
     18 
     19 // NewUnicorn ...
     20 // Constructs a new real unicorn from fairy dust and sprinkles
     21 func NewUnicorn() (*RealUnicorn, error) {
     22 	dev, err := spi.Open("/dev/spidev0.0", 9000000, 0)
     23 	if err != nil {
     24 		return nil, err
     25 	}
     26 
     27 	return &RealUnicorn{
     28 		BaseUnicorn{
     29 			pixels: makePixels(16, 16),
     30 		},
     31 		dev,
     32 	}, nil
     33 }
     34 
     35 func (u *RealUnicorn) Show() {
     36 	// Width * height * colours + leading bit
     37 	width := int(u.GetWidth())
     38 	height := int(u.GetHeight())
     39 	sz := (width * height * 3) + 1
     40 	write := make([]byte, sz)
     41 
     42 	// Add the leading bit
     43 	write[0] = 0x72
     44 	// Add all the pixel values
     45 	ix := 1
     46 	for x := 0; x < width; x++ {
     47 		for y := 0; y < height; y++ {
     48 			for j := 0; j < 3; j++ {
     49 				write[ix] = byte(u.pixels[x][y][j])
     50 				ix++
     51 			}
     52 		}
     53 	}
     54 	// Write to the device
     55 	err := u.device.Transfer(write)
     56 	if err != nil {
     57 		log.Printf("Error writing to SPI device %v", err)
     58 	}
     59 }
     60 
     61 func (u *RealUnicorn) Off() {
     62 	u.Close()
     63 }
     64 
     65 func (u *RealUnicorn) Close() error {
     66 	return u.device.Close()
     67 }
     68 
     69 // MainLoop ...
     70 // Do nothing until SIGTERM, then close the SPI library
     71 func (u *RealUnicorn) MainLoop() {
     72 	c := make(chan os.Signal, 2)
     73 	signal.Notify(c, os.Interrupt, syscall.SIGTERM)
     74 	<-c
     75 	u.Close()
     76 }