Display interface bit rates on Adafruit LCD display for eth0 and eth1

netstats2lcd.py

import copy
import time
import Adafruit_CharLCD as LCD

ifstats = {
    "eth0": { "tx": 0, "rx": 0 },
    "eth1": { "tx": 0, "rx": 0 }
}

ifnames = [ "eth0", "eth1" ]

ifstats_prev = copy.deepcopy(ifstats)

lastTime = time.time_ns()
deltaTime = 1;

def get_ifstats():
    global deltaTime
    global lastTime
    global ifstats_prev
    global ifstats

    # find the time delta since last reading
    now = time.time_ns()
    deltaTime = now - lastTime
    lastTime = now
    # avoid divide by zero in rate calculation
    if 0 == deltaTime:
        deltaTime = 1
    
    # save previous stats for delta computation
    ifstats_prev = copy.deepcopy(ifstats)
    # parse the current stats (pseudo-file has one line per interface, including lo and wlan0)
    with open("/proc/net/dev", "r") as f:
        for index, line in enumerate(f):
            fields = line.split()
            for ifname in ifnames:
                if fields[0] == (ifname + ":"):
                    ifstats[ifname]["rx"] = int(fields[1])
                    ifstats[ifname]["tx"] = int(fields[9])

# we only have 8 characters for the number, so display up to 1 Gbps in kbps

def scale_bps(bytesNow, bytesPrev, deltaTimeNS):
    deltaBits = 8 * (bytesNow - bytesPrev)
    bytesPerNS = deltaBits / deltaTimeNS
    kBitsPerSec = 1000000 * bytesPerNS
    return int(kBitsPerSec)

try:
    # Initialize the LCD using the pins
    lcd = LCD.Adafruit_CharLCDBackpack(address=0x21)
    # turn LCD backlight on
    lcd.set_backlight(0)
    lcd.clear()
    get_ifstats()

    while True:
        time.sleep(1)
        get_ifstats()
        eth0_tx_bps = scale_bps(ifstats["eth0"]["tx"], ifstats_prev["eth0"]["tx"], deltaTime)
        eth0_rx_bps = scale_bps(ifstats["eth0"]["rx"], ifstats_prev["eth0"]["rx"], deltaTime)
        eth1_tx_bps = scale_bps(ifstats["eth1"]["tx"], ifstats_prev["eth1"]["tx"], deltaTime)
        eth1_rx_bps = scale_bps(ifstats["eth1"]["rx"], ifstats_prev["eth1"]["rx"], deltaTime)
        lcdline = "{:>8}{:>8}\n{:>8}{:>8}".format(eth0_rx_bps, eth0_tx_bps, eth1_rx_bps, eth1_tx_bps)
        lcd.home()
        lcd.message(lcdline)
        #print(lcdline + "\n")

# hit control-C to exit quietly
except KeyboardInterrupt:
    pass
finally:
    # turn off the backlight on exit
    lcd.set_backlight(1)