the_python_code
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the_python_code [2016/12/21 15:53] – walkeradmin | the_python_code [2023/03/09 22:35] (current) – external edit 127.0.0.1 | ||
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\\ | \\ | ||
<color red> | <color red> | ||
+ | |||
+ | ---- | ||
+ | |||
==== The File Header ==== | ==== The File Header ==== | ||
This is to identify to the Linux system what this file type is, and to allow the author to add some information (anything following a hash # is just a comment) | This is to identify to the Linux system what this file type is, and to allow the author to add some information (anything following a hash # is just a comment) | ||
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# | # | ||
</ | </ | ||
+ | |||
+ | ---- | ||
+ | ==== A reminder of the pin outs ==== | ||
+ | The following section is just comments, but it is a nice reminder of which GPIO pins on the Raspberry Pi that this Python code is going to try to address. | ||
+ | \\ | ||
< | < | ||
# The wiring for the LCD is as follows: | # The wiring for the LCD is as follows: | ||
Line 38: | Line 46: | ||
# 5 : R/W (Read Write) | # 5 : R/W (Read Write) | ||
# 6 : Enable or Strobe | # 6 : Enable or Strobe | ||
- | # 7 : Data Bit 0 | + | # 7 : Data Bit 0 - |
- | # 8 : Data Bit 1 | + | # 8 : Data Bit 1 - |
- | # 9 : Data Bit 2 | + | # 9 : Data Bit 2 - |
- | # 10: Data Bit 3 | + | # 10: Data Bit 3 - |
# 11: Data Bit 4 - GPIO pin 13 - Physical pin 33 | # 11: Data Bit 4 - GPIO pin 13 - Physical pin 33 | ||
# 12: Data Bit 5 - GPIO pin 06 - Physical pin 31 | # 12: Data Bit 5 - GPIO pin 06 - Physical pin 31 | ||
Line 48: | Line 56: | ||
# 15: LCD Backlight | # 15: LCD Backlight | ||
# 16: LCD Backlight | # 16: LCD Backlight | ||
+ | </ | ||
+ | ---- | ||
+ | ==== Import Python Libraries ==== | ||
+ | Python uses standard libraries to provide standard functions, so you don't have to code everyday tasks such as printing etc. Here we are importing some standard libraries for our project. | ||
+ | \\ | ||
+ | < | ||
#import | #import | ||
import RPi.GPIO as GPIO | import RPi.GPIO as GPIO | ||
Line 55: | Line 69: | ||
import fcntl | import fcntl | ||
import struct | import struct | ||
+ | </ | ||
+ | ---- | ||
+ | ==== 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). | ||
+ | \\ | ||
+ | \\ | ||
+ | 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. | ||
+ | \\ | ||
+ | < | ||
# Define GPIO to LCD mapping | # Define GPIO to LCD mapping | ||
LCD_RS = 26 | LCD_RS = 26 | ||
Line 63: | Line 86: | ||
LCD_D6 = 5 | LCD_D6 = 5 | ||
LCD_D7 = 11 | LCD_D7 = 11 | ||
+ | </ | ||
+ | ---- | ||
+ | ==== 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. | ||
+ | \\ | ||
+ | < | ||
# Define some device constants | # Define some device constants | ||
LCD_WIDTH = 40 # Maximum characters per line | LCD_WIDTH = 40 # Maximum characters per line | ||
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LCD_CMD = False | LCD_CMD = False | ||
- | # Do I need to change line 2 address | + | # Address |
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 77: | Line 105: | ||
E_PULSE = 0.0005 | E_PULSE = 0.0005 | ||
E_DELAY = 0.0005 | E_DELAY = 0.0005 | ||
+ | </ | ||
+ | ---- | ||
+ | ==== 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 red> | ||
+ | \\ | ||
+ | < | ||
def main(): | def main(): | ||
# Main program block | # Main program block | ||
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GPIO.setup(LCD_D6, | GPIO.setup(LCD_D6, | ||
GPIO.setup(LCD_D7, | GPIO.setup(LCD_D7, | ||
+ | </ | ||
+ | ---- | ||
+ | ==== 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. | ||
+ | \\ | ||
+ | < | ||
########################################## | ########################################## | ||
# | # | ||
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lcd_init() | lcd_init() | ||
+ | # If using DHCP this is required, or code runs before network is ready. | ||
lcd_string(" | lcd_string(" | ||
time.sleep(5) | time.sleep(5) | ||
+ | </ | ||
+ | ---- | ||
+ | ==== Read File ==== | ||
+ | Here we are opening the file <color red>'/ | ||
+ | \\ | ||
+ | < | ||
while True: | while True: | ||
## Open the file with read only permit | ## Open the file with read only permit | ||
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## close the file after reading the lines. | ## close the file after reading the lines. | ||
f.close() | f.close() | ||
+ | </ | ||
- | # Display | + | ---- |
- | # lcd_string(" | + | ==== Set which line to write to the LCD ==== |
- | # lcd_string(" | + | 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(" | + | \\ |
- | + | \\ | |
- | # time.sleep(2) # x second delay | + | line< |
+ | \\ | ||
+ | \\ | ||
+ | This above example tells the Pi to use Line <color red> | ||
+ | \\ | ||
+ | < | ||
# 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(" | lcd_string(" | ||
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time.sleep(1) # x second delay | time.sleep(1) # x second delay | ||
+ | </ | ||
+ | ---- | ||
+ | ==== LCD Write Code ==== | ||
+ | The code below takes our text and writes it to the LCD, do not make any changes to this section. | ||
+ | \\ | ||
+ | < | ||
########################################## | ########################################## | ||
# | # | ||
Line 234: | Line 293: | ||
</ | </ | ||
\\ | \\ | ||
+ | |||
+ | ---- | ||
+ | |||
\\ | \\ | ||
\\ | \\ | ||
+ | ===== Complete Code Set ===== | ||
\\ | \\ | ||
- | \\ | + | Below is the complete file without any breaks, you can cut and paste this to create your own UMD LCD. |
- | \\ | + | |
- | \\ | + | |
- | \\ | + | |
- | \\ | + | |
- | \\ | + | |
- | \\ | + | |
- | \\ | + | |
\\ | \\ | ||
\\ | \\ | ||
Line 348: | 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(" | ||
- | # lcd_string(" | ||
- | # lcd_string(" | ||
- | |||
- | # 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.txt · Last modified: 2023/03/09 22:35 by 127.0.0.1