isendev.com

Raspberry Pi + LCD + Python (System Information)

By isendev.

Posted on 2014/01/14 22:07.

Tagged as: hardware, programming, diy, python.

Raspberry Pi LCD showing system information.

Here is the Python code to use the HD44780 compatible LCD as a simple, but quite useful, system information monitor. The source has been separated in 3 files, for better understanding (lcd.py, sysinfo.py and lcd.sysinfo.py). It currently shows Memory, CPU, Filesystem and Network information, but can be easily modified to include other information provided by PSUtil (process and netstat information, I/O statistics, etc.).

<lcd.py>

Functions used to manage the 20x4 LCD display through the Raspberry Pi GPIO port.

#!/usr/bin/python
# 20x4 LCD Control Functions.
# Original code by: Matt Hawkins
# Site: http://www.raspberrypi-spy.co.uk
# Modified by: Antonio Perdices.
# Site: https://www.isendev.com
# 14/01/2014

# LCD Wiring.
# 1 : GND                    - TO GROUND
# 2 : 5V                     - TO +5V
# 3 : Contrast (0-5V)        - TO 10K POT OUTPUT
# 4 : RS (Register Select)
# 5 : R/W (Read Write)       - TO GROUND
# 6 : Enable or Strobe
# 7 : Data Bit 0             - NOT USED
# 8 : Data Bit 1             - NOT USED
# 9 : Data Bit 2             - NOT USED
# 10: Data Bit 3             - NOT USED
# 11: Data Bit 4
# 12: Data Bit 5
# 13: Data Bit 6
# 14: Data Bit 7
# 15: Backlight 5V           - NOT USED
# 16: Backlight GND          - NOT USED

# Imports.
import RPi.GPIO as GPIO
import time

# GPIO to LCD Mapping.
# Using Broadcom GPIO numbers
LCD_RS = 7
LCD_E  = 8
LCD_D4 = 25
LCD_D5 = 24
LCD_D6 = 23
LCD_D7 = 18

# Constants.

# Max chars per line.
LCD_WIDTH = 20

# LCD Byte Mode. 'Character' or 'Command'.
LCD_CHR = True
LCD_CMD = False

# 1st Line LCD RAM address.
LCD_LINE_1 = 0x80
# 2nd Line LCD RAM address.
LCD_LINE_2 = 0xC0
# 3rd Line LCD RAM address.
LCD_LINE_3 = 0x94
 # 4th Line LCD RAM address.
LCD_LINE_4 = 0xD4

# Timing constants.
E_PULSE = 0.00005
E_DELAY = 0.00005

# Enable GPIO.
def lcd_gpio_enable():

    # Disable warnings.
    GPIO.setwarnings(False)

    # Use Broadcom GPIO numbers.
    GPIO.setmode(GPIO.BCM)

    # Enable GPIO outputs.
    GPIO.setup(LCD_E, GPIO.OUT)  # E
    GPIO.setup(LCD_RS, GPIO.OUT) # RS
    GPIO.setup(LCD_D4, GPIO.OUT) # DB4
    GPIO.setup(LCD_D5, GPIO.OUT) # DB5
    GPIO.setup(LCD_D6, GPIO.OUT) # DB6
    GPIO.setup(LCD_D7, GPIO.OUT) # DB7

# Init display function.
def lcd_init():

    # Init commands.
    lcd_byte(0x33,LCD_CMD)
    lcd_byte(0x32,LCD_CMD)
    lcd_byte(0x28,LCD_CMD)
    lcd_byte(0x0C,LCD_CMD)
    lcd_byte(0x06,LCD_CMD)
    lcd_byte(0x01,LCD_CMD)

# Send byte data to display.
# bits = data.
# mode = 'True' for character or 'False' for command.
def lcd_byte(bits, mode):

    # Register Select.
    GPIO.output(LCD_RS, mode)

    # Send High bits.
    GPIO.output(LCD_D4, False)
    GPIO.output(LCD_D5, False)
    GPIO.output(LCD_D6, False)
    GPIO.output(LCD_D7, False)
    if bits&0x10==0x10:
        GPIO.output(LCD_D4, True)
    if bits&0x20==0x20:
        GPIO.output(LCD_D5, True)
    if bits&0x40==0x40:
        GPIO.output(LCD_D6, True)
    if bits&0x80==0x80:
        GPIO.output(LCD_D7, True)

    # Toggle 'Enable' pin.
    time.sleep(E_DELAY)
    GPIO.output(LCD_E, True)
    time.sleep(E_PULSE)
    GPIO.output(LCD_E, False)
    time.sleep(E_DELAY)

    # Low bits.
    GPIO.output(LCD_D4, False)
    GPIO.output(LCD_D5, False)
    GPIO.output(LCD_D6, False)
    GPIO.output(LCD_D7, False)
    if bits&0x01==0x01:
        GPIO.output(LCD_D4, True)
    if bits&0x02==0x02:
        GPIO.output(LCD_D5, True)
    if bits&0x04==0x04:
        GPIO.output(LCD_D6, True)
    if bits&0x08==0x08:
        GPIO.output(LCD_D7, True)

    # Toggle 'Enable' pin
    time.sleep(E_DELAY)
    GPIO.output(LCD_E, True)
    time.sleep(E_PULSE)
    GPIO.output(LCD_E, False)
    time.sleep(E_DELAY)

# Send string to display.
# Style parameter:
# 1 = Left justified.
# 2 = Centred.
# 3 = Right justified.
def lcd_string(message,style):

    if style==1:
        message = message.ljust(LCD_WIDTH," ")
    elif style==2:
        message = message.center(LCD_WIDTH," ")
    elif style==3:
        message = message.rjust(LCD_WIDTH," ")

    for i in range(LCD_WIDTH):
        lcd_byte(ord(message[i]),LCD_CHR)

# Blank LCD.
def lcd_clear():

    lcd_byte(LCD_LINE_1, LCD_CMD)
    lcd_string("",2)
    lcd_byte(LCD_LINE_2, LCD_CMD)
    lcd_string("",2)
    lcd_byte(LCD_LINE_3, LCD_CMD)
    lcd_string("",2)
    lcd_byte(LCD_LINE_4, LCD_CMD)
    lcd_string("",2)

<sysinfo.py>

Functions to get system information using PSUtil, a cross-platform process and system utilities module for Python.

#!/usr/bin/python
# System Information Functions.
# Author: Antonio Perdices.
# Site: https://www.isendev.com
# 14/01/2014

# Imports.
import lcd
import psutil
import subprocess

# Show memory info.
def lcd_show_mem():

    MEM_TOTAL_LABEL = "MEM Total:"
    MEM_TOTAL = "%(mem).2fMB" % {'mem': psutil.virtual_memory().total/1024.0/1024.0}
    MEM_TOTAL = MEM_TOTAL.rjust(lcd.LCD_WIDTH - len(MEM_TOTAL_LABEL)," ")

    MEM_FREE_LABEL = "MEM Free:"
    MEM_FREE = "%(mem).2fMB" % {'mem': psutil.virtual_memory().free/1024.0/1024.0}
    MEM_FREE = MEM_FREE.rjust(lcd.LCD_WIDTH - len(MEM_FREE_LABEL)," ")

    SWAP_TOTAL_LABEL = "SWAP Total:"
    SWAP_TOTAL = "%(mem).2fMB" % {'mem': psutil.swap_memory().total/1024.0/1024.0}
    SWAP_TOTAL = SWAP_TOTAL.rjust(lcd.LCD_WIDTH - len(SWAP_TOTAL_LABEL)," ")

    SWAP_FREE_LABEL = "SWAP Free:"
    SWAP_FREE = "%(mem).2fMB" % {'mem': psutil.swap_memory().free/1024.0/1024.0}
    SWAP_FREE = SWAP_FREE.rjust(lcd.LCD_WIDTH - len(SWAP_FREE_LABEL)," ")

    lcd.lcd_byte(lcd.LCD_LINE_1, lcd.LCD_CMD)
    lcd.lcd_string(MEM_TOTAL_LABEL + MEM_TOTAL, 1)
    lcd.lcd_byte(lcd.LCD_LINE_2, lcd.LCD_CMD)
    lcd.lcd_string(MEM_FREE_LABEL + MEM_FREE, 1)
    lcd.lcd_byte(lcd.LCD_LINE_3, lcd.LCD_CMD)
    lcd.lcd_string(SWAP_TOTAL_LABEL + SWAP_TOTAL, 1)
    lcd.lcd_byte(lcd.LCD_LINE_4, lcd.LCD_CMD)
    lcd.lcd_string(SWAP_FREE_LABEL + SWAP_FREE, 1)

# Show cpu info.
def lcd_show_cpu():

    CPU_READ = psutil.cpu_times_percent(interval=1, percpu=False)

    CPU_USER_LABEL = "CPU User:"
    CPU_USER = "%(cpu).2f%%" % {'cpu': CPU_READ.user}
    CPU_USER = CPU_USER.rjust(lcd.LCD_WIDTH - len(CPU_USER_LABEL)," ")

    CPU_NICE_LABEL = "CPU Nice:"
    CPU_NICE = "%(cpu).2f%%" % {'cpu': CPU_READ.nice}
    CPU_NICE = CPU_NICE.rjust(lcd.LCD_WIDTH - len(CPU_NICE_LABEL)," ")

    CPU_SYSTEM_LABEL = "CPU System:"
    CPU_SYSTEM = "%(cpu).2f%%" % {'cpu': CPU_READ.system}
    CPU_SYSTEM = CPU_SYSTEM.rjust(lcd.LCD_WIDTH - len(CPU_SYSTEM_LABEL)," ")

    CPU_IDLE_LABEL = "CPU Idle:"
    CPU_IDLE = "%(cpu).2f%%" % {'cpu': CPU_READ.idle}
    CPU_IDLE = CPU_IDLE.rjust(lcd.LCD_WIDTH - len(CPU_IDLE_LABEL)," ")

    lcd.lcd_byte(lcd.LCD_LINE_1, lcd.LCD_CMD)
    lcd.lcd_string(CPU_USER_LABEL + CPU_USER, 1)
    lcd.lcd_byte(lcd.LCD_LINE_2, lcd.LCD_CMD)
    lcd.lcd_string(CPU_NICE_LABEL + CPU_NICE, 1)
    lcd.lcd_byte(lcd.LCD_LINE_3, lcd.LCD_CMD)
    lcd.lcd_string(CPU_SYSTEM_LABEL + CPU_SYSTEM, 1)
    lcd.lcd_byte(lcd.LCD_LINE_4, lcd.LCD_CMD)
    lcd.lcd_string(CPU_IDLE_LABEL + CPU_IDLE, 1)

# Show filesystem info.
def lcd_show_fsinfo():

    FS_READ = psutil.disk_usage('/')

    FS_TOTAL_LABEL = "SD Total:"
    FS_TOTAL = "%(disk).2fGB" % {'disk': FS_READ.total/1024.0/1024.0/1024.0}
    FS_TOTAL = FS_TOTAL.rjust(lcd.LCD_WIDTH - len(FS_TOTAL_LABEL)," ")

    FS_FREE_LABEL = "SD Free:"
    FS_FREE = "%(disk).2fGB" % {'disk': FS_READ.free/1024.0/1024.0/1024.0}
    FS_FREE = FS_FREE.rjust(lcd.LCD_WIDTH - len(FS_FREE_LABEL)," ")

    FS_USED_LABEL = "SD Used:"
    FS_USED = "%(disk).2fGB" % {'disk': FS_READ.used/1024.0/1024.0/1024.0}
    FS_USED = FS_USED.rjust(lcd.LCD_WIDTH - len(FS_USED_LABEL)," ")

    FS_PERCENT_LABEL = "SD Used %:"
    FS_PERCENT = "%(disk).2f%%" % {'disk': FS_READ.percent}
    FS_PERCENT = FS_PERCENT.rjust(lcd.LCD_WIDTH - len(FS_PERCENT_LABEL)," ")

    lcd.lcd_byte(lcd.LCD_LINE_1, lcd.LCD_CMD)
    lcd.lcd_string(FS_TOTAL_LABEL + FS_TOTAL, 1)
    lcd.lcd_byte(lcd.LCD_LINE_2, lcd.LCD_CMD)
    lcd.lcd_string(FS_FREE_LABEL + FS_FREE, 1)
    lcd.lcd_byte(lcd.LCD_LINE_3, lcd.LCD_CMD)
    lcd.lcd_string(FS_USED_LABEL + FS_USED, 1)
    lcd.lcd_byte(lcd.LCD_LINE_4, lcd.LCD_CMD)
    lcd.lcd_string(FS_PERCENT_LABEL + FS_PERCENT, 1)

# Show network info.
def lcd_show_netinfo(interface):

    IP_READ = subprocess.check_output(["/sbin/ifconfig", interface])

    IP_ADDRESS_LABEL = "ADD:"
    if not "addr:" in IP_READ:
        IP_ADDRESS = "0.0.0.0"
    else:
        IP_ADDRESS = IP_READ.split("\n")[1].split()[1][5:]
    IP_ADDRESS = IP_ADDRESS.rjust(lcd.LCD_WIDTH - len(IP_ADDRESS_LABEL)," ")

    IP_MASK_LABEL = "MSK:"
    if not "addr:" in IP_READ:
        IP_MASK = "0.0.0.0"
    else:
        IP_MASK = IP_READ.split("\n")[1].split()[3][5:]
    IP_MASK = IP_MASK.rjust(lcd.LCD_WIDTH - len(IP_MASK_LABEL)," ")

    IP_READ = subprocess.check_output(["/sbin/ip", "route"])

    IP_GW_LABEL = "GTW:"
    if not "default" in IP_READ:
        IP_GW = "0.0.0.0"
    else:
        IP_GW = IP_READ.split("\n")[0].split()[2]
    IP_GW = IP_GW.rjust(lcd.LCD_WIDTH - len(IP_GW_LABEL)," ")

    IP_NET_LABEL = "NET:"
    if not "default" in IP_READ:
        IP_NET = "0.0.0.0"
    else:
        IP_NET = IP_READ.split("\n")[1].split()[0]
    IP_NET = IP_NET.rjust(lcd.LCD_WIDTH - len(IP_NET_LABEL)," ")

    lcd.lcd_byte(lcd.LCD_LINE_1, lcd.LCD_CMD)
    lcd.lcd_string(IP_ADDRESS_LABEL + IP_ADDRESS, 1)
    lcd.lcd_byte(lcd.LCD_LINE_2, lcd.LCD_CMD)
    lcd.lcd_string(IP_MASK_LABEL + IP_MASK, 1)
    lcd.lcd_byte(lcd.LCD_LINE_3, lcd.LCD_CMD)
    lcd.lcd_string(IP_GW_LABEL + IP_GW, 1)
    lcd.lcd_byte(lcd.LCD_LINE_4, lcd.LCD_CMD)
    lcd.lcd_string(IP_NET_LABEL + IP_NET, 1)

<lcd.sysinfo.py>

Main program.

#!/usr/bin/python
# 20x4 LCD System Information Script for Raspberry Pi.
# Author: Antonio Perdices.
# Site: https://www.isendev.com
# 14/01/2014

# Imports.
import time
import lcd
import sysinfo

LOOP_TIME = 5

# Main program.
def main():

    # Enable GPIO.
    lcd.lcd_gpio_enable()

    # Init display.
    lcd.lcd_init()

    # Write message to console.
    # print("Press Ctrl+C to exit...")

    COUNTER = 1

    # Main loop.
    while True:

        if (COUNTER % 4 == 0):
            sysinfo.lcd_show_mem()
            COUNTER = COUNTER + 1
        elif (COUNTER % 4 == 1):
            sysinfo.lcd_show_cpu()
            COUNTER = COUNTER + 1
        elif (COUNTER % 4 == 2):
            sysinfo.lcd_show_netinfo("eth0")
            COUNTER = COUNTER + 1
        else:
            sysinfo.lcd_show_fsinfo()
            COUNTER = 0

        time.sleep(LOOP_TIME)

# Execute main program.
if __name__ == '__main__':
    try:
        main()
    except KeyboardInterrupt:
        print("\nKeyboard interrupt detected... Bye!")
        lcd.lcd_clear()
        pass

<lcd.init>

If you want to run the display program at startup, here is an init script for Debian.

### BEGIN INIT INFO
# Provides: LCD - CPU / Memory / Filesystem / Network
# Required-Start: $remote_fs $syslog
# Required-Stop: $remote_fs $syslog
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: Liquid Crystal Display
# Description: LCD - CPU / Memory / Filesystem / Network
### END INIT INFO

#! /bin/sh
# /etc/init.d/lcd

export HOME
case "$1" in
    start)
        echo "Starting LCD..."
        /root/Dev.LCD/lcd.sysinfo/lcd.sysinfo.py 2>&1 &
    ;;
    stop)
        echo "Stopping LCD..."
        LCD_PID=`ps auxwww | grep lcd.sysinfo.py | head -1 | awk '{print $2}'`
        kill -9 $LCD_PID
    ;;
    *)
        echo "Usage: /etc/init.d/lcd {start|stop}"
        exit 1
    ;;
esac
exit 0

Permalink