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the_python_code [2016/12/21 16:00] – walkeradminthe_python_code [2023/03/09 22:35] (current) – external edit 127.0.0.1
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 ---- ----
-==== Import Python Libraries ==== +==== Define some Constants ==== 
-Rather than referring to GPIO pin numbers in the code, we are declaring some variables that we can use to reference the GPIO pin numbers to actual functions. (So the LCD Reset that uses GPIO pin 26 can be called by using just LCD_RS for example)+Rather than referring to GPIO pin numbers in the code, we are declaring some variables that we can use to reference the GPIO pin numbers to actual functions. (So the LCD Reset that uses GPIO pin 26 can be called by using just LCD_RS for example).  
 +\\  
 +\\  
 +The advantage of using this method is, if a pin number changes, we can change it here, and not have to hunt through the code for every occurrence of that pin number.
 \\  \\ 
 <file> <file>
Line 87: Line 90:
 ---- ----
 ==== Import Python Libraries ==== ==== Import Python Libraries ====
- +Below we are defining some more constants, these are to do with the LCD lines and chars, as well as the timing.
- +
 \\  \\ 
-\\  +<file>
-\\  +
-\\  +
-\\  +
- +
 # Define some device constants # Define some device constants
 LCD_WIDTH = 40    # Maximum characters per line LCD_WIDTH = 40    # Maximum characters per line
Line 102: Line 98:
 LCD_CMD = False LCD_CMD = False
  
-# Do I need to change line 2 address for 40 char display?+# Address for 40 char display
 LCD_LINE_1 = 0x80 # LCD RAM address for the 1st line LCD_LINE_1 = 0x80 # LCD RAM address for the 1st line
 LCD_LINE_2 = 0xC0 # LCD RAM address for the 2nd line LCD_LINE_2 = 0xC0 # LCD RAM address for the 2nd line
Line 109: Line 105:
 E_PULSE = 0.0005 E_PULSE = 0.0005
 E_DELAY = 0.0005 E_DELAY = 0.0005
 +</file>
  
 +----
 +==== Code Start ====
 +This is where the main code starts, as this program runs in a loop, anything above the line <color red>def main():</color> is only run once at program start. Anything below is run once per loop.
 +\\ 
 +\\ 
 +<color red>GPIO.setmode(GPIO.BCM)</color> tells the Pi we are using the GPIO board numbers, not the Pin numbers.
 +\\ 
 +<file>
 def main(): def main():
   # Main program block   # Main program block
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   GPIO.setup(LCD_D6, GPIO.OUT) # DB6   GPIO.setup(LCD_D6, GPIO.OUT) # DB6
   GPIO.setup(LCD_D7, GPIO.OUT) # DB7   GPIO.setup(LCD_D7, GPIO.OUT) # DB7
 +</file>
  
 +----
 +==== Program Start ====
 +This is the main body of the code that runs the LCD, to save splitting this up I will comment in this section.
 +\\ 
 +<file>
 ########################################## ##########################################
 #             PROGRAM  START             # #             PROGRAM  START             #
Line 130: Line 141:
   lcd_init()   lcd_init()
  
 +  # If using DHCP this is required, or code runs before network is ready.
   lcd_string(" Waiting 5 Seconds for Network Start",LCD_LINE_1) # wait 5 seconds for DHCP process to finish   lcd_string(" Waiting 5 Seconds for Network Start",LCD_LINE_1) # wait 5 seconds for DHCP process to finish
   time.sleep(5)   time.sleep(5)
 +</file>
  
 +---- 
 +==== Read File ==== 
 +Here we are opening the file <color red>'/home/pi/Python/my_data.txt</color> for edit (so we can read and write to it). This file contains the 8 lines of text for our LCDs. 
 +\\ 
 +<file>
   while True:   while True:
     ## Open the file with read only permit     ## Open the file with read only permit
Line 155: Line 172:
     ## close the file after reading the lines.     ## close the file after reading the lines.
     f.close()     f.close()
 +</file>
  
-#    Display the current IP Address information +---- 
-#    lcd_string("  lo" + " " + get_ip_address('lo'),LCD_LINE_1) +==== Set which line to write to the LCD ==== 
-#    lcd_string("  UMD 04",LCD_LINE_1) +The code below sets what lines from the 8 lines are used (so Master Pi displays lines 1&2, the fourth Pi displays Lines 7&8. 
-#    lcd_string(" eth0" + " " + get_ip_address('eth0'),LCD_LINE_2) +\\  
- +\\  
-#    time.sleep(2) # x second delay +line<color red>1</color>,LCD_LINE_<color blue>1</color> 
 +\\  
 +\\  
 +This above example tells the Pi to use Line <color red>1</color> from our text file, and put is on line <color blue>1</color> of our LCD 
 +\\  
 +<file>
     # write line 1 and 2 to the LCD (Line7 and Line8 because this is UMD4)     # write line 1 and 2 to the LCD (Line7 and Line8 because this is UMD4)
     lcd_string(" " + line1,LCD_LINE_1)     lcd_string(" " + line1,LCD_LINE_1)
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     time.sleep(1) # x second delay     time.sleep(1) # x second delay
 +</file>
  
 +---- 
 +==== LCD Write Code ==== 
 +The code below takes our text and writes it to the LCD, do not make any changes to this section. 
 +\\  
 +<file>
 ########################################## ##########################################
 #     CHANGE NO CODE BELOW THIS LINE     # #     CHANGE NO CODE BELOW THIS LINE     #
Line 266: Line 293:
 </file> </file>
 \\  \\ 
 +
 +----
 +
 \\  \\ 
 \\  \\ 
 +===== Complete Code Set =====
 \\  \\ 
-\\  +Below is the complete file without any breaks, you can cut and paste this to create your own UMD LCD.
-\\  +
-\\  +
-\\  +
-\\  +
-\\  +
-\\  +
-\\ +
 \\  \\ 
 \\  \\ 
Line 380: Line 404:
     ## close the file after reading the lines.     ## close the file after reading the lines.
     f.close()     f.close()
- 
-#    Display the current IP Address information 
-#    lcd_string("  lo" + " " + get_ip_address('lo'),LCD_LINE_1) 
-#    lcd_string("  UMD 04",LCD_LINE_1) 
-#    lcd_string(" eth0" + " " + get_ip_address('eth0'),LCD_LINE_2) 
- 
-#    time.sleep(2) # x second delay 
  
     # write line 1 and 2 to the LCD (Line7 and Line8 because this is UMD4)     # write line 1 and 2 to the LCD (Line7 and Line8 because this is UMD4)
the_python_code.1482336027.txt.gz · Last modified: 2023/03/09 22:35 (external edit)