DotStar.py

"""DotStar, python module to use DotStar LEDs,
micropython version

created February 10, 2023
modified February 11, 2023
modified April 24, 2023
modified April 23, 2024"""

"""
Copyright 2023 Owain Martin

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
"""

import machine
import utime as time

class DotStar:
    
    def __init__(self, sdo, clk, numLEDs, brightness = 3, spiBus = 0, baudrate = 1000000, auto_write = False):
        
        # set up SPI connection details
        self.sdo = machine.Pin(sdo)
        self.clk = machine.Pin(clk)        
        self.spi = machine.SPI(spiBus, baudrate = baudrate, sck= self.clk, mosi = self.sdo)
        
        # initialize list to hold individual LED colour & brightness details
        # initially set to all off and default brightness (as indicated by the -1)
        # (R, G, B, Brightness)
        self.dotList = [(0,0,0, -1) for x in range(numLEDs)]
        
        self.brightness = brightness
        self.auto_write = auto_write
        
        return
        
    def __setitem__(self, key, value):
        """__setitem__, function to set an indivdual or
        a range of LEDs values in the dotstar pixel list"""
        
        self.dotList[key] = value
        if self.auto_write == True:
            self.show()
            
        return
        
    def __getitem__(self, key):
        """__getitem__, function to get/return an indivdual or
        a range of LEDs values from the dotstar pixel list"""
        
        return self.dotList[key]
    
    def fill(self, colour, step = 1):
        """fill, function to set the dotstar pixel list
        to all the same colour"""       
        
        for i in range(0, len(self.dotList), step):
            self.dotList[i] = colour
        
        if self.auto_write == True:
            self.show()
            
        return    
    
    def show(self, brightness = None):
        """show, function to write the pixel data to
        the LEDs to update/show the new values"""
        
        dataList = [] # list containing all formatted data to send to dotstar string
        numLEDs = len(self.dotList)        
        
        # first part of each LED frame consists of 3 1-bits and 5 brightness bits (i.e. 111bbbbb)
        # go through each LED/pixel(p) and add the 4 bytes of data for each
        # to the dataList in the right order
        for p in self.dotList:
            if p[3] == -1:
                if brightness != None:
                    brightness = 0xE0 | brightness
                else:
                    brightness = 0xE0 | self.brightness
            else:
                brightness = 0xE0 | p[3]
                
            dataList.extend([brightness, p[2], p[1], p[0]])
        
        # add 4 byte/32 bit start frame to beginning of dataList
        dataList[:0] = [0,0,0,0] # 32 bit 0 start frame
        
        # add end frame to dataList, size dependent on number
        # of LEDs in string
        if numLEDs < 64:
            dataList.extend([0x03, 0x00]) # end frame
        else:
            dataList.extend([0xFF for x in range(12)]) # end frame
            
        # write data out to dotstar string
        dataTransfer = bytearray(dataList) # creates buffer object             
        self.spi.write(dataTransfer)
        
        return
        
if __name__ == "__main__":
    
    # initialize dotstar object
    dots = DotStar(sdo = 19, clk = 18, numLEDs = 64, baudrate = 1000000, auto_write = False)
    
    # delay between effects
    delay = 2
    
    # set first 32 LED to green at minimal (1) brightness    
    for i in range(0,32):
        dots[i] = (0, 150, 0, 1)
        
    # set next 32 LEDs to green at maximum (31) brightness
    for i in range(32,64):
        dots[i] = (0, 150, 0, 31)
    dots.show()
    time.sleep(delay)
    
    # set all LEDS to red at default brightness
    dots.fill((150,0,0,-1))
    dots.show()
    time.sleep(delay)
    
    # change default brightness to 15
    dots.brightness = 15
    
    # set LEDs 8-14 to blue at default brightness
    dots[8:15] = [(0, 0, 150, -1)] * 8    
    dots.show()
    time.sleep(delay)
    
    # change current brightness to 9 of 31
    dots.show(brightness = 9)
    time.sleep(delay)
    
    # print current colour & brightness value for
    # LED 31
    print(dots[31])    
    
    # alternate method of turning LEDS off
    # but still maintaining last colour values
    #dots.show(brightness = 0)
    #time.sleep(delay)
    #dots.show()
    #time.sleep(delay)
    
    # turn off all LEDs
    dots.fill((0,0,0,0))
    dots.show()    
    print('done')