sign.py for Alphasign BetaBrite

gistfile1.txt

import alphasign                                                                                                                                                                                                                                                                                                       
import sys                                                                                                                                                                                                                                                                                                             
import time                                                                                                                                                                                                                                                                                                            
import urllib2                                                                                                                                                                                                                                                                                                         
                                                                                                                                                                                                                                                                                                                       
def update_sign():                                                                                                                                                                                                                                                                                                     
                                                                                                                                                                                                                                                                                                                       
        sign = alphasign.Serial(device='/dev/ttyUSB0')                                                                                                                                                                                                                                                                 
        sign.connect()                                                                                                                                                                                                                                                                                                 
        sign.clear_memory()                                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                                       
        # create an empty alphasign.String                                                                                                                                                                                                                                                                             
        alpha_str = alphasign.String()                                                                                                                                                                                                                                                                                 
                                                                                                                                                                                                                                                                                                                       
        # create a single alphasign.Text object with a placeholder for our alphasign.String                                                                                                                                                                                                                            
        alpha_txt = alphasign.Text(alpha_str.call(),mode=alphasign.modes.COMPRESSED_ROTATE)                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                                       
        # allocate memory for these objects on the sign                                                                                                                                                                                                                                                                
        sign.allocate((alpha_str,alpha_txt))                                                                                                                                                                                                                                                                           
                                                                                                                                                                                                                                                                                                                       
        # tell sign to only display the text part                                                                                                                                                                                                                                                                      
        sign.set_run_sequence((alpha_txt,))                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                                       
        # write objects                                                                                                                                                                                                                                                                                                
        for obj in (alpha_str,alpha_txt):                                                                                                                                                                                                                                                                              
            sign.write(obj)                                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                                       
        # This gives time for the serial write to complete before we issue the next write.                                                                                                                                                                                                                             
        time.sleep(5)                                                                                                                                                                                                                                                                                                  
                                                                                                                                                                                                                                                                                                                       
        last_payload = ''                                                                                                                                                                                                                                                                                              
                                                                                                                                                                                                                                                                                                                       
        while True:                                                                                                                                                                                                                                                                                                    
                                                                                                                                                                                                                                                                                                                       
            try:                                                                                                                                                                                                                                                                                                       
                # fetch new-line separated plain text from Interweb                                                                                                                                                                                                                                                    
                payload = urllib2.urlopen("https://server.appletonmakerspace.org/beta-brite-message-file.txt").read()                                                                                                                                                                                                  
            except Exception:                                                                                                                                                                                                                                                                                          
                payload = 'HALP! Internet down!?'                                                                                                                                                                                                                                                                      
                                                                                                                                                                                                                                                                                                                       
            # alert bystanders with beep when we update                                                                                                                                                                                                                                                                
            if payload != last_payload:                                                                                                                                                                                                                                                                                
                sign.beep(frequency=20, duration=1)                                                                                                                                                                                                                                                                    
                last_payload = payload                                                                                                                                                                                                                                                                                 
                                                                                                                                                                                                                                                                                                                       
            # loop over each line of plain text, displaying for 10 seconds                                                                                                                                                                                                                                             
            for line in payload.splitlines():                                                                                                                                                                                                                                                                          
                alpha_str.data = line                                                                                                                                                                                                                                                                                  
                sign.write(alpha_str)                                                                                                                                                                                                                                                                                  
                time.sleep(10)                                                                                                                                                                                                                                                                                         
                                                                                                                                                                                                                                                                                                                       
            # when the last line is read, the while loop repeats and fetches again                                                                                                                                                                                                                                     
                                                                                                                                                                                                                                                                                                                       
if __name__ == "__main__":                                                                                                                                                                                                                                                                                             
    update_sign()