Engineering Projects in Community Service

Thursday, April 23, 2015

Code for Gas booking python

Create a file called config.txt and add following lines

phonenum: 9666261963
min_weight: 3
gas_agency: 9985203976

smartgasbooking.py

import serial
from random import randint
from time import sleep
from threading import Thread
import threading

resume=threading.Event()

def read_configfile():
fin = open("config.txt","r")
lines= tuple(fin)
config = {}
for line in lines:
config[line.split(":")[0]]=line.split(":")[1]
fin.close()
return config

config_arr=read_configfile()

def weight_read():
global config_arr
global resume
while True :
try:
ser=serial.Serial('/dev/ttyAMA0',9600,timeout=1)
ser.flush()
num=ser.inWaiting()
if(num != 0):
s=ser.read(num)
print "weight",s
weight= s.split(" Kg.")[0]
#print weight
if(float(weight) < 4):
resume.clear()
#call_number(config_arr["phonenum"])
call_number("9666261963")
print "calling"
ser.close()
except:
print "...."

def call_number(phnum):
try:
global resume
ser = serial.Serial('/dev/ttyUSB0',9600,timeout=1)
ser.flush()
print "Calling ...",phnum
cmd="ATD"+str(phnum)+";\r"
ser.write(cmd)
sleep(15)
ser.write('ATH\r')
ser.close()
except:
print "call_error"
resume.set()

try:
resume.set()
wt_thread=Thread(target = weight_read);
wt_thread.start()
wt_thread.join()
except:
print " thread Error"

Interfacing Load cell with Raspberry Pi

Connectivity of Load cell to Load cell Amplifier for weighing scale

Input voltage - Excitation
Red wire --------- Excitation input voltage (+)
Black wire -------- Excitation input Ground(-)

Output voltage - Signal
Green wire ------- Signal output (+)
White wire ------ Signal output (-)

Load cell documentation : http://www.sunrom.com/p/load-cell-40-kg
Load cell Amplifier documentation : http://www.sunrom.com/p/load-cell-amplifier-for-weighing-scale-serial-output

Connectivity of Load cell Amplifier for weighing scale to Raspberry Pi
5V ---------- pin 4 (5v)
GND --------- pin 6 (GND)
RXD --------- pin 8 (TXD)
TXD --------- pin 10 (RXD)

Python code for weight reading

import serial
from random import randint
from time import sleep
from threading import Thread

def weight_read():
    global config_arr
    while True :
     try:
        ser=serial.Serial('/dev/ttyAMA0',9600,timeout=1)
        ser.flush()
        num=ser.inWaiting()
        if(num != 0):
            s=ser.read(num)
            print s
            weight= s.split(" Kg.")[0]
        #print weight
            if(float(weight) < 4):
                #call_number(config_arr["phonenum"])
                print "calling"
        ser.close()
     except:
        print "Weight read error"

try:
    wt_thread=Thread(target = weight_read);
    wt_thread.start()
    wt_thread.join()
except:
    print " thread creation Error"

Friday, April 10, 2015

Interfacing SIM900A GSM Modem with Raspberry Pi

gsm_phone.py

import serial

import time

ser = serial.Serial('/dev/ttyUSB0',9600,timeout=1)

# 9600 is the default Baudrate for SIM900A modem

ser.flush()

ser.write('ATD9020XXXXXX;\r')

# AT command to call a number using GSM Modem

#ser.read(2)

# read 2 bytes of data from the serial port

time.sleep(10)

# wait for 10 seconds

ser.write('ATH\r')

# Hold the call

ser.close()

# close the serial port

connect RXD of USB2Serial to TXD of GSM Modem and TXD of Serial to RXD of GSM Modem. Also check if you can make a call to the modem and see whether a ring sound, so that network connection can be ensured.

You may use AT+CMGS=”phonenumber” for the sms