Finally I’m home again after a week taking care of my parents house and dog while they were on vacation. I’ve continued work on my Arduino project and today I connected it to my network monitoring software op5 to see if it worked as intended. It did! Maybe you’re wondering what it’s supposed to do?
It’s basically a two row LCD display, two LEDs and an Arduino. This is connected to the computer running op5 via USB. A program, written in Python, is running on the op5 computer. This transmits current out- and indoor temperature which is displayed in the LCD and in addition the LEDs (a green and a red one) shows me the overall status of my network. If the green LED’s lit everything’s OK, if the red’s lit something’s wrong. Pretty simple.
The monitoring server
Let’s start with the monitoring server. It has a Python program running which sends data to the Arduino.
#!/usr/bin/python
import time
import serial
import string, sys, os, time
#Serial port
serial_name = "/dev/ttyUSB0"
hostname = "jupiter.nickebo.net"
community = "public"
oid1 = "1.3.6.1.4.1.31440.10.5.1.1.0"
oid2 = "1.3.6.1.4.1.31440.10.5.1.1.2"
def printLCD():
# configure the serial connections (the parameters differs on the device you are connecting to)
try:
ser = serial.Serial(serial_name,9600)
except:
print "Could not open serial port " + serial_name
raise SystemExit()
time.sleep(2)
print "Printing: Out: " + str(round(sensor, 1))
ser.write('0Out: ' + str(round(sensor, 1)) + ' C')
time.sleep(2)
print "Printing: In: " + str(round(sensor2, 1))
ser.write('1In: ' + str(round(sensor2, 1)) + ' C')
time.sleep(2)
statusfile = os.popen("/opt/monitor/bin/monitorstats |grep 'Services Ok'|awk '{print $5 $7 $9}'")
status = int(statusfile.read())
statusfile.close()
print "op5 status: " + str(int(status))
if(int(status) > 0):
print "alarm"
ser.write('alarm')
else:
print "reset"
ser.write('reset')
while 1:
#Connect to the 1-wire server
try:
sensorfile = os.popen('/usr/bin/snmpget -c ' + community + ' -v 2c ' + hostname + ' ' + oid1 + ' |cut -d \\" -f 2')
sensor = str(sensorfile.read())
sensor = float(sensor)
except:
print "Could not connect to " + hostname + " or error reading probe"
raise SystemExit(3)
try:
sensorfile2 = os.popen('/usr/bin/snmpget -c ' + community + ' -v 2c ' + hostname + ' ' + oid2 + ' |cut -d \\" -f 2')
sensor2 = str(sensorfile2.read())
sensor2 = float(sensor2)
except:
print "Could not connect to " + hostname + " or error reading probe"
raise SystemExit(3)
printLCD()
time.sleep(10)
This is pretty much a dirty hack, but it works. I use a while-loop which tries to fetch the temperature data from my 1-wire server via SNMP. If this succeeds it calls the printLCD function which sends data to the Arduino. The function also checks the status of op5, sending “alarm” if something’s wrong and “reset” if everything’s OK. As you can see the data sent for the temperature readings start with either 0 or 1, this is a simple header which tells the Arduino if the data is to be printed on line 0 or 1 on the LCD. Unfortunately I’ve been too lazy to do proper comments in the code, this will be sorted in the final version.
If you’ve been able to decrypt my crappy Python code above you might want to see the other side of the serial line? Namely the code for the Arduino.
The Arduino, where the real magic happens
The Arduino uses C++ (well, it’s VERY similar to C++) for the programming part. I’m using a library called LiquidCrystal to control the HD44780 LCD display, this makes it a whole lot easier. Beside that it’s handling the incoming serial data and sorting it out that’s the challenge. Now, the code.
#include
// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
void setup(){
// set up the LCD's number of columns and rows:
lcd.begin(16, 2);
// initialize the serial communications:
Serial.begin(9600);
//Grön
pinMode(8, OUTPUT);
//Röd
pinMode(9, OUTPUT);
//Sätt Grön LED till high
digitalWrite(8, HIGH);
}
void loop()
{
// when characters arrive over the serial port...
if (Serial.available()) {
char inData[18];
char inChar=-1;
char cmdVar[2];
byte index=0;
// wait a bit for the entire message to arrive
delay(100);
// read all the available characters
while (Serial.available() > 0) {
if(index < 17) // One less than the size of the array
{
inChar = Serial.read(); // Read a character
inData[index] = inChar; // Store it
if(index == 0)
{
cmdVar[0] = inChar;
cmdVar[1] = '\0';
}
index++; // Increment where to write next
inData[index] = '\0'; // Null terminate the string
}
}
if(strcmp(inData,"alarm") == 0)
{
digitalWrite(9, HIGH);
digitalWrite(8, LOW);
}
else if(strcmp(inData,"reset") == 0)
{
digitalWrite(9, LOW);
digitalWrite(8, HIGH);
}
else
{
byte i=1;
char dispVar[18];
for(i=1;i<17;i++)
{
dispVar[i-1] = inData[i];
}
Serial.write(cmdVar);
if(strcmp(cmdVar,"0") == 0)
{
//lcd.clear();
lcd.setCursor(0,0);
lcd.write(dispVar);
}
else if(strcmp(cmdVar,"1") == 0)
{
//lcd.clear();
lcd.setCursor(0,1);
lcd.write(dispVar);
}
}
}
}At the first glimpse this code is “WTF? what did he do? this is the crappiest code I’ve ever…” and yes, it IS crappy. But it works, I haven’t refined it in any way. So, what does it do? I initialize the LCD, loads libraries, etc. at the top. Also sets digital pin 8 and 9 as outputs for my LEDs. It assumes everything is OK and sets the green LED to high, which means it will be lit. Now, if data is received on the serial port (emulated via an FTDI chip over USB) the data is put in inData and inData is null terminated with ‘\0′. This is straight forward, receive the data and put it in an array. I then check if it matches “alarm” or “reset”, if so the green/red LED is lit. If not, I place the first char in a separate variable called cmdVar. If it’s equal to 0 or 1 i print out the rest of the data on either row 0 or row 1. If the first char it’s either 0 or 1 nothing happens, it’s not valid since I don’t know which line to print it on.
The next step is to order all stuff needed and solder it all together and make a permanent installation. Hopefully I’ll get this done next week.
Arduino prototype display working
Above is the Arduino at present, displaying current indoor and outdoor temperatures. As you can see the green LED is lit, everything is OK in my network. I’ll keep it like this until I’ve soldered the new unit.
