imaging.py

# IMPORTANT!
#
# THIS CODE IS UNFINISHED AND SOME FUNCTIONS (I.E. fit_to_screen()) ARE BROKEN!
# I made this code for myself, not for others, never meant to be released, just shared it related to another problem. 
# Of course I do not ban you from it's usage, but I warned you.
#
# Distributed (or not) under the Creative Commons 2.0 license... nah, nobody cares.
#
# :author: Nagy Gergely






import spidev
import time
from PIL import Image, ImageDraw

'''register adresses'''
NOOP = 0x0			# only needed if more devices are cascaded
DIGIT0 = 0x1
DIGIT1 = 0x2		# the register vaules in binary are equvivalents of the 
DIGIT2 = 0x3		#    illuminated and non-illuminated pixels in the columb
DIGIT3 = 0x4		#    from top to bottom (if decodemode is false)
DIGIT4 = 0x5
DIGIT5 = 0x6
DIGIT6 = 0x7
DIGIT7 = 0x8
DECODEMODE = 0x9	# 0x0 for LED screen
INTENSITY = 0xA		# brightness, 0x0 - 0x0F
SCANLIMIT = 0xB		# number of columbs to display 
SHUTDOWN = 0xC		# 0x0 turns the screen off (the chip remains avaible for programming)
DISPLAYTEST = 0xF	# 0x1 turns test mode on (all pixels illuminated at max brightness


class LedDisplay(object):


        
        
        
        def __init__(self, device, speed=1000000, image=None):
            '''
            Initializes the hardware SPI connection on CS pin `device` at the speed `speed`, and sets deafults. 
            The maximum serial connection speed for MAX7219 is 10MHz. Also initializes the picture: it loads
            and fits the provided `picture` if there is, else creates a new one.
            '''
            
            assert device == 0 or device == 1, 'wrong device ID'
            assert 3814 <= speed <= 10000000, 'invaild connection speed'
            self.display = spidev.SpiDev()
            self.display.open(0, device)
            #display.speed_in_hz = speed
            self.send(SCANLIMIT, 0x7)		# show all 8 digits
            self.send(DECODEMODE, 0x0)	# use matrix (not digits)
            self.send(SHUTDOWN, 0x1)		# not shutdown mode
            self.send(DISPLAYTEST, 0x0)	# no display test
            if image is None:
                self.image = Image.new('1', (8, 8))
            else:
                self.image = fit_to_screen(image)
            
            self.send(0x1, 0xAA)
        
        def send(self, *args):
            '''
            Defines a fancier way of sending data to the device.
            '''
            self.display.xfer2(list(args))
            
        
        def fit_to_screen(self, image):
        
            '''
            If the picture is not a 2-colored one, and/or not 8x8 sized, it will be converted to fit.
            '''
            
            if (image.mode != '1'):
                #print 'Image is converted to 1-bit color.'
                image = image.convert('1')
                
            if (image.size != (8, 8)):
                #print 'Image has been resized.'
                x, y = image.size
                if (x >= y):
                    width = 8
                    height = int(8 * y/x)
                else:
                    width = int(8 * x/y)
                    height = 8
                image = image.resize((width, height))
                return image
                
            
        def show(self, image):
            '''
            Draws the given image on the LED display.
            ''' 
            # calculating the numbers to what we have to set the columbs' registers 
            width, height = image.size
            assert 1 <= width < 9 , 1 <= height <= 9
            pixels = []
            for x in range(0, width):
                num = 0
                for y in range(0, height):
                    pix = image.getpixel((x, y))
                    num = num + pix/255 * 2**y
                pixels.append(num)
            
            # sending the data to the chip
            for x in range(1, 9):
                self.send(x, pixels[x-1])


        def set_brightness(self, percent):
            
            if not 0 <= percent <= 100:
                raise ValueError('Brightness value must be between 0 and 16')
            if percent == 0:
                self.send(SHUTDOWN, 0x0)
            else:
                value = int(15.0/100 * percent)
                self.send(SHUTDOWN, 0x1)
                self.send(INTENSITY, value)

            
        def finish(self):
        
            image = Image.new('1', (8,8))
            self.show(image)
            self.display.close()

def main():
    
    disp = LedDisplay(device = 1)
    im = Image.new('1', (8, 8))
    draw = ImageDraw.Draw(im, mode='1')
    delay = 1
    
    disp.set_brightness(16)
    for j in range(0, 1):
        for i in range(0, 4):
            draw.rectangle((i, i, 7-i, 7-i), 0, 255)
            time.sleep(delay)
            disp.show(im)
            
    for x in range(0, 8):
        for y in range(0, 8):
            if((x+y)%2 == 0):
                im.putpixel((x, y), 255)
    for i in range(0, 11):
        disp.set_brightness(10*i)
        time.sleep(1)
    disp.finish()

if __name__=='__main__':
    main()