diff --git a/blink/main.py b/blink/main.py
index 09c2286..1933248 100644
--- a/blink/main.py
+++ b/blink/main.py
@@ -1,12 +1,19 @@
+# A led blinking every half second for five times.
 import time
 
 from machine import Pin
 
 
+# create an output pin on pin #2
+# because for ESP-12 board the led light using GPIO2 which is pin2.
+# the led operate in "inverted" mode, which means the pin value is '1' will set
+# the led off, and pin value "0" will set the led on.
 led = Pin(2, Pin.OUT)
-for i in range(3):
-    time.sleep(.5)
-    led.value(1)
+# set the value high to turn the led off.
+led.value(1)
+time.sleep(1)
+for i in range(5):
     time.sleep(.5)
     led.value(0)
-
+    time.sleep(.5)
+    led.value(1)
diff --git a/boot.py b/boot.py
index 91135a5..28a5587 100644
--- a/boot.py
+++ b/boot.py
@@ -7,7 +7,8 @@
 import time
 import machine
 
-sta_if = network.WLAN(network.STA_IF); sta_if.active(True)
+sta_if = network.WLAN(network.STA_IF)
+sta_if.active(True)
 
 try:
     with open("passwords.txt") as f:
@@ -24,8 +25,9 @@
 
     sta_if.connect(station, password)
 
-    for i in range(15):
-        print(".")
+    #for i in range(15):
+    for i in range(30):
+        print(".", end=' ')
 
         if sta_if.isconnected():
             break
@@ -36,3 +38,5 @@
         break
     else:
         print("Connection could not be made.\n")
+if sta_if.isconnected():
+    print("\nConnected as: {}".format(sta_if.ifconfig()[0]))
diff --git a/dc_motor/DC_motor_control_over_WiFi.txt b/dc_motor/DC_motor_control_over_WiFi.txt
new file mode 100644
index 0000000..4016894
--- /dev/null
+++ b/dc_motor/DC_motor_control_over_WiFi.txt
@@ -0,0 +1,21 @@
+DC motor control over WiFi
+1. The NodeMCU board pin 12 and pin 13 is connected to the motor driver (L293D)
+pin 2 and pin 7 to control the motor rotating forward or backward or stop.
+The pin values corresponding to motor direction is as follows:
+Pin2 = 0 Pin7 = 0 ---> motor stop
+Pin2 = 1 Pin7 = 0 ---> motor forward
+Pin2 = 0 Pin7 = 1 ---> motor backward
+There are four buttons on our motor control web page for controlling motor's
+on/off/forward/backward.
+
+2. The speed of the motor is also controlled by sending different PWM duty cycle
+through pin14 to the L293D enable pin.
+We have four button on our motor control web page for controlling the speed:
+25 duty cycle, 50 duty cycle, 75 duty cycle and 100 duty cycle.
+
+3. The speed of the motor can also be controlled by a position transducer using
+the only analog input pin A0. The analogy input pin converts the position
+transducer voltage output into digital value(0, 1023). This digital value is then
+used as input parameter for the pwm.duty() function to control the speed of the
+motor seamlessly. We have a button on our motor control web page to test this
+stepless speed control.
diff --git a/dc_motor/main.py b/dc_motor/main.py
new file mode 100644
index 0000000..062598e
--- /dev/null
+++ b/dc_motor/main.py
@@ -0,0 +1,201 @@
+# This code controls a DC motor speed and direction over Wifi using
+# Nodemcu esp8266 and L293D motor driver.
+# http://localhost:8080/motor_control is the homepage for DC motor control.
+try:
+    import usocket as socket
+except:
+    import socket
+
+response_404 = """HTTP/1.0 404 NOT FOUND
+
+<h1>404 Not Found</h1>
+"""
+
+response_500 = """HTTP/1.0 500 INTERNAL SERVER ERROR
+
+<h1>500 Internal Server Error</h1>
+"""
+
+
+response_template = """HTTP/1.0 200 OK
+
+%s
+"""
+import machine
+from time import sleep
+from machine import Pin
+
+# set up the pins of nodeMCU and L293D
+# 1. We use GPIN 12 and 13 of nodeMCU as output control pins.
+# GPIO12 and 13 is connected to the INPUT Pin 2 and 7 of L293D.
+# Pin2 = 0 Pin7 = 0 ---> motor off
+# Pin2 = 1 Pin7 = 0 ---> motor forward
+# Pin2 = 0 Pin7 = 1 ---> motor backward
+out1 = Pin(12, Pin.OUT)
+out2 = Pin(13, Pin.OUT)
+
+# 2. We use GPID14 of nodeMCU to send the PWM signal to control the speed of motor.
+# GPID14 of nodeMCU is connected to the enable 1,2 (Pin 1) of L293D.
+pwm = Pin(14)
+pwm = machine.PWM(pwm)
+pwm.duty(1023)
+
+# 3. We use Analog input pin A0 to connect a transducer to change the speed of
+# the motor.
+adc = machine.ADC(0)
+
+home_page_str = """
+<!DOCTYPE HTML>
+<html>
+<h1 align=center>NodeMCU DC motor control over WiFi</h1><br><br>
+<br><br>
+<a href=\"http://192.168.1.168:8080/motor_on\"><button> Motor On </button></a>
+<a href=\"http://192.168.1.168:8080/motor_off\"><button> Motor Off </button></a>
+<a href=\"http://192.168.1.168:8080/motor_forward\"><button> Motor Forward </button></a>
+<a href=\"http://192.168.1.168:8080/motor_backward\"><button> Motor Backward </button></a>
+<br>
+<br>
+<a href=\"http://192.168.1.168:8080/duty_25\"><button> Duty Cycle 25% </button></a>
+<a href=\"http://192.168.1.168:8080/duty_50\"><button> Duty Cycle 50% </button></a>
+<a href=\"http://192.168.1.168:8080/duty_75\"><button> Duty Cycle 75% </button></a>
+<a href=\"http://192.168.1.168:8080/duty_100\"><button> Duty Cycle 100% </button></a>
+<br>
+<br>
+<a href=\"http://192.168.1.168:8080/duty_100\"><button> Stepless Speed Control</button></a>
+<br>
+<br>
+<br>
+"""
+# create homepage veiw function.
+def home_page():
+    body = home_page_str + '</html>'
+    return response_template % body
+
+# create a motor on view function.
+def motor_on():
+    out1.value(1)
+    out2.value(0)
+    pwm.duty(1023)
+    body = home_page_str + '<p> Motor is on</p> </html>'
+    return response_template % body
+
+# create a motor off view function.
+def motor_off():
+    out1.value(0)
+    out2.value(0)
+    body = home_page_str + 'Motor is stopped.'
+    return response_template % body
+
+# create a motor forward veiw function.
+def motor_forward():
+    out1.value(0)
+    out2.value(0)
+    sleep(3)
+    out1.value(1)
+    out2.value(0)
+    #pwm.duty(1023)
+    body = home_page_str + 'Motor rotating in forward direction.'
+    return response_template % body
+
+# create a motor backward veiw function.
+def motor_backward():
+    out1.value(0)
+    out2.value(0)
+    sleep(3)
+    out1.value(0)
+    out2.value(1)
+    #pwm.duty(1023)
+    body = home_page_str + 'Motor rotating in backward direction.'
+    return response_template % body
+
+# create PWM duty cycle = 25 veiw function.
+def duty_25():
+    pwm.duty(255)
+    body = home_page_str + 'PWM duty cycle 25%.'
+    return response_template % body
+
+# create PWM duty cycle = 50 veiw function.
+def duty_50():
+    pwm.duty(512)
+    body = home_page_str + 'PWM duty cycle 50%.'
+    return response_template % body
+
+# create PWM duty cycle = 75 veiw function.
+def duty_75():
+    pwm.duty(767)
+    body = home_page_str + 'PWM duty cycle 75%.'
+    return response_template % body
+
+# create PWM duty cycle = 100 veiw function.
+def duty_100():
+    pwm.duty(1023)
+    body = home_page_str + 'PWM duty cycle 100%.'
+    return response_template % body
+
+# create analog input duty cycle veiw function.
+def analog_duty():
+    motor_duty_cycle = adc.read()
+    pwm.duty(motor_duty_cycle)
+    body = home_page_str + 'PWM duty cycle {}'.format(motor_duty_cycle)
+    return response_template % body
+
+# routing dictionary for different view functions.
+handlers = {
+    'motor_control': home_page,
+    'motor_on': motor_on,
+    'motor_off': motor_off,
+    'motor_forward': motor_forward,
+    'motor_backward': motor_backward,
+    'duty_100': duty_100,
+    'duty_75': duty_75,
+    'duty_50': duty_50,
+    'duty_25': duty_25,
+    'analog_duty': analog_duty,
+}
+
+def main():
+    s = socket.socket()
+    ai = socket.getaddrinfo("0.0.0.0", 8080)
+    addr = ai[0][-1]
+
+    s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+
+    s.bind(addr)
+    s.listen(5)
+    print("Listening, connect your browser to http://<this_host>:8080/")
+
+    while True:
+        sleep(.5)
+        print("Before accept:")
+        res = s.accept()
+        print("After accept:")
+        client_s = res[0]
+        client_addr = res[1]
+        req = client_s.recv(4096)
+        print("Request:")
+        print(req)
+
+        # This first line of a request looks like "GET /arbitrary/path/ HTTP/1.1 "
+        # It has three parts and seperated by a space char (' ').
+        # So the first part is the GET method, second is the path, the third is the
+        # HTTP version used. We only need the second part.
+        # The first line of a request is: req.decode().split('\r\n')[0]
+        # The second part of first line is:
+        # req.decode().split('\r\n')[0].split(" ")[1]
+        try:
+            path = req.decode().split('\r\n')[0].split(' ')[1]
+            # http://localhost:8080/motor_control is the homepage.
+            handler = handlers[path.strip('/').split('/')[0]]
+            response = handler()
+        except KeyError:
+            response = response_404
+        except Exception as e:
+            response = response_500
+            print(str(e))
+
+        client_s.send(b"\r\n".join([line.encode() for line in response.split("\n")]))
+
+        client_s.close()
+        print()
+
+main()
diff --git a/passwords.txt b/passwords.txt
index 9f2747f..97eab85 100644
--- a/passwords.txt
+++ b/passwords.txt
@@ -1,2 +1 @@
-EarlGreyTea HotHotHot
-MyHomeAccessPoint aueiUeh73NB
+Jia2 123456
diff --git a/simple_web_server/main.py b/simple_web_server/main.py
index b860471..9e2382c 100644
--- a/simple_web_server/main.py
+++ b/simple_web_server/main.py
@@ -3,12 +3,22 @@
 except:
     import socket
 
+response_404 = """HTTP/1.0 404 NOT FOUND
+
+<h1>404 Not Found</h1>
+"""
+
+response_500 = """HTTP/1.0 500 INTERNAL SERVER ERROR
+
+<h1>500 Internal Server Error</h1>
+"""
 response_template = """HTTP/1.0 200 OK
 
 %s
 """
 import machine
-import ntptime, utime
+import ntptime
+import utime
 from machine import RTC
 from time import sleep
 
@@ -19,6 +29,7 @@
     seconds = 0
 rtc.datetime(utime.localtime(seconds))
 
+# time view
 def time():
     body = """<html>
 <body>
@@ -30,6 +41,17 @@ def time():
 
     return response_template % body
 
+# dummy view
+def dummy():
+    body = "This is a dummy endpoint"
+    return response_template % body
+
+# routing dictionary for different view functions.
+handlers = {
+    'time': time,
+    'dummy': dummy,
+}
+
 def main():
     s = socket.socket()
     ai = socket.getaddrinfo("0.0.0.0", 8080)
@@ -39,10 +61,12 @@ def main():
 
     s.bind(addr)
     s.listen(5)
-    print("Listening, connect your browser to http://<this_host>:8080/")
+    print("Listening, connect your browser to http://", end='')
+    print(addr)
 
     while True:
         sleep(.5)
+        print("Before accept")
         res = s.accept()
         client_s = res[0]
         client_addr = res[1]
@@ -50,7 +74,26 @@ def main():
         print("Request:")
         print(req)
 
-        response = time()
+        # This first line of a request looks like "GET /arbitrary/path/ HTTP/1.1 "
+        # It has three parts and seperated by a space char (' ').
+        # So the first part is the GET method, second is the path, the third is the
+        # HTTP version used. We only need the second part.
+        # The first line of a request is: req.decode().split('\r\n')[0]
+        # The second part of first line is:
+        # req.decode().split('\r\n')[0].split(" ")[1]
+        try:
+            path = req.decode().split('\r\n')[0].split(' ')[1]
+            # the path like /dummy/dog/, we want to only get 'dummy'
+            # so we need to strip slashes from the left or right side of the path.
+            # and then get the first string from the remaining path.
+            handler = handlers[path.strip('/').split('/')[0]]
+            # if the handler is 'dummy', then we will call dummy().
+            response = handler()
+        except KeyError:
+            response = response_404
+        except Exception as e:
+            response = response_500
+            print(str(e))
 
         client_s.send(b"\r\n".join([line.encode() for line in response.split("\n")]))
 
diff --git a/web_server/main.py b/web_server/main.py
index dd66055..c0350ff 100644
--- a/web_server/main.py
+++ b/web_server/main.py
@@ -12,25 +12,24 @@
 
 <h1>500 Internal Server Error</h1>
 """
-
 response_template = """HTTP/1.0 200 OK
 
 %s
 """
-
 import machine
-import ntptime, utime
+import ntptime
+import utime
 from machine import RTC
 from time import sleep
 
+rtc = RTC()
 try:
     seconds = ntptime.time()
 except:
     seconds = 0
-
-rtc = RTC()
 rtc.datetime(utime.localtime(seconds))
 
+# time view function
 def time():
     body = """<html>
 <body>
@@ -42,16 +41,50 @@ def time():
 
     return response_template % body
 
+# dummy view function
 def dummy():
     body = "This is a dummy endpoint"
+    return response_template % body
+
+from machine import Pin
+led = Pin(14, Pin.OUT)
+# create a light_on view function.
+def light_on():
+    led.value(1)
+    sleep(5)
+    led.value(0)
+    body = 'Your LED is turned on for 5 second then turned off.'
+    return response_template % body
+
+# create a light_off view function.
+def light_off():
+    led.value(0)
+    sleep(5)
+    led.value(1)
+    body = 'Your LED is turned off for 5 second then truned on.'
+    return response_template % body
+
+# create a switch_state view function.
+switch = Pin(12, Pin.IN)
+def switch_state():
+    body = 'Switch State: {}'.format(switch.value())
+    return response_template % body
 
+# create a light_state view function.
+adc = machine.ADC(0)
+def light_state():
+    body = 'Light state:{}'.format(adc.read())
     return response_template % body
 
-pin = machine.Pin(10, machine.Pin.IN)
 
+# routing dictionary for different view functions.
 handlers = {
     'time': time,
     'dummy': dummy,
+    'light_on': light_on,
+    'light_off': light_off,
+    'switch': switch_state,
+    'light': light_state,
 }
 
 def main():
@@ -63,9 +96,10 @@ def main():
 
     s.bind(addr)
     s.listen(5)
-    print("Listening, connect your browser to http://<this_host>:8080")
+    print("Listening, connect your browser to http://<this_host>:8080/")
 
     while True:
+        sleep(.5)
         res = s.accept()
         client_s = res[0]
         client_addr = res[1]
@@ -73,9 +107,20 @@ def main():
         print("Request:")
         print(req)
 
+        # This first line of a request looks like "GET /arbitrary/path/ HTTP/1.1 "
+        # It has three parts and seperated by a space char (' ').
+        # So the first part is the GET method, second is the path, the third is the
+        # HTTP version used. We only need the second part.
+        # The first line of a request is: req.decode().split('\r\n')[0]
+        # The second part of first line is:
+        # req.decode().split('\r\n')[0].split(" ")[1]
         try:
-            path = req.decode().split("\r\n")[0].split(" ")[1]
+            path = req.decode().split('\r\n')[0].split(' ')[1]
+            # the path like /dummy/dog/, we want to only get 'dummy'
+            # so we need to strip slashes from the left or right side of the path.
+            # and then get the first string from the remaining path.
             handler = handlers[path.strip('/').split('/')[0]]
+            # if the handler is 'dummy', then we will call dummy() view function.
             response = handler()
         except KeyError:
             response = response_404
diff --git a/web_server/main_old.py b/web_server/main_old.py
new file mode 100644
index 0000000..dd66055
--- /dev/null
+++ b/web_server/main_old.py
@@ -0,0 +1,91 @@
+try:
+    import usocket as socket
+except:
+    import socket
+
+response_404 = """HTTP/1.0 404 NOT FOUND
+
+<h1>404 Not Found</h1>
+"""
+
+response_500 = """HTTP/1.0 500 INTERNAL SERVER ERROR
+
+<h1>500 Internal Server Error</h1>
+"""
+
+response_template = """HTTP/1.0 200 OK
+
+%s
+"""
+
+import machine
+import ntptime, utime
+from machine import RTC
+from time import sleep
+
+try:
+    seconds = ntptime.time()
+except:
+    seconds = 0
+
+rtc = RTC()
+rtc.datetime(utime.localtime(seconds))
+
+def time():
+    body = """<html>
+<body>
+<h1>Time</h1>
+<p>%s</p>
+</body>
+</html>
+""" % str(rtc.datetime())
+
+    return response_template % body
+
+def dummy():
+    body = "This is a dummy endpoint"
+
+    return response_template % body
+
+pin = machine.Pin(10, machine.Pin.IN)
+
+handlers = {
+    'time': time,
+    'dummy': dummy,
+}
+
+def main():
+    s = socket.socket()
+    ai = socket.getaddrinfo("0.0.0.0", 8080)
+    addr = ai[0][-1]
+
+    s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+
+    s.bind(addr)
+    s.listen(5)
+    print("Listening, connect your browser to http://<this_host>:8080")
+
+    while True:
+        res = s.accept()
+        client_s = res[0]
+        client_addr = res[1]
+        req = client_s.recv(4096)
+        print("Request:")
+        print(req)
+
+        try:
+            path = req.decode().split("\r\n")[0].split(" ")[1]
+            handler = handlers[path.strip('/').split('/')[0]]
+            response = handler()
+        except KeyError:
+            response = response_404
+        except Exception as e:
+            response = response_500
+            print(str(e))
+
+        client_s.send(b"\r\n".join([line.encode() for line in response.split("\n")]))
+
+        client_s.close()
+        print()
+
+main()