Week 17

After a week of research, I finally connected WEMOS D1 mini to CAS. However, nothing happens when I use the app. I am sure the lines are connected correctly, WEMOS shows working normal, but the car still did not start.

That few days I need to use the car, so I removed the WEMOS D1 mini. Unfortunately, my car cannot start even the key is in the car. I realized that it would not be as easy as loading a board into CAS. I called a trailer and dragged the car to a garage. The car mechanic told me the CAS detected a power off abnormal, so it bans ignition system working until the system is rested.

In addition, CAS connected with driving computer, if I want to add demo board into the CAS I must modify the data of driving computer and use special tools to modify the data of CAS. These data are encrypted, I need to go to a large car dealer and let the car mechanic to help me modify because this is a top technology.

Now there are two options, one is to dismantle the CAS and design a new anti-theft system, the second is to send my car to modify the data.

However, just leaving a little time, I can only reach this step. I will finish it when I have free time.


Week 15

The car mechanic teaches me how to remove the CAS this week. The first step is to open the car’s hood. Use a wrench to disconnect the vehicle battery’s negative cable. Turn the nut fixed on the battery counterclockwise. The next step is remove the plastic panel at the bottom of the driver’s door. Use a screwdriver to pry open the bezel. Press inward on the plastic sheet around the door. Pull the panel out of the border. Then remove the alarm module from the bezel. The alarm module is a small box with an antenna projecting out on one side. Use wire cutters to cut off all wires and plastic brackets that connect the alarm and door. Disconnect the wires that connect the alarm to the ignition system, horn and power lock. Pull the doorbell out the border. Finally, put on the new anti-theft system, connect the corresponding line. I need spend some time to learn about this.

Week 14

I found the CAS in my car in this week.

I opened the bezel below the steering wheel. CAS is located back of the bezel below the steering wheel. CAS mainly has 10 wires, one wire is connected with the power supply, the 6 wires are connected with the corresponding sensors, one wire is connected with the ignition system, one wire is connected with the alarm and the last one for send alarm message.


Week 13

For this week, I need make some changes to my car. Before that I must have a general understanding about the anti-theft system of my car.

The anti-theft system of my car named Car Access. CAS as anti-theft system, it can start the BMW vehicle. A signal transceiver chip is installed in the car key and a toroidal coil surrounds the ignition switch, through which the CAS control unit supplies energy to the signal transceiver chip, so do not need to install a battery in the key. Power and data transfer are the same as transformers, between the loop antenna (coil) on the ignition switch and the signal transceiver chip mounted in the key. The key sends the data to the CAS control unit. If the data is correct, the CAS makes car start by a relay inside of control module, encrypted enable signal will be send by a data cable. When the key is near the car, the signal transceiver chip sends a signal to the coil. The driver can only start the engine by pressing the Start button when CAS determines that the signal is correct.

Week 12

The second method is highly viable, saves money while reducing working hours, so this week’s job is to add that board into the security system. Need to start car and turn off the theft system at the same time so I need to change the code of WEMOS D1 mini. The previous code could only control one switch, so I added a bit of code to make it possible to control two switches.

Only writing code is not enough, I’ve also modified the application. Modified application, click the ON button while access to link of turn off the anti-theft system power supply. Click the OFF button while access to link of turn on the anti-theft system power supply.

Week 10

This week I contacted the car mechanic. He told me there are two ways to achieve my goal.

The first way is remove the car’s original anti-theft system, the development a new anti-theft system and makes it work with the WEMOS D1 mini. In fact, just need unplug the fuse of the anti-theft system is an easy way when not using the original anti-theft system. However, install a new anti-theft system needs to be installed in accordance with the original line so remove the original anti-theft system is necessary.

The second way is retaining the original anti-theft system, makes WEMOS D1 mini join the original anti-theft system. Makes the security system turned off after I start the car with my phone.

Week 9

With the progress of science and technology, in order to cope with the escalating car theft, people have developed a variety of ways and different anti-theft devices from generation to generation. At present, anti-theft devices can be divided into three categories according to their structure: mechanical, electronic and network.

Locks, steering wheel locks and gear shift locks are basically mechanical anti-theft devices, which mainly rely on locking clutch, brake, throttle, steering wheel or gear to achieve the purpose of anti-theft, but only anti-theft without alarm.

Insert, pushbutton and remote control, etc. belong to the electronic anti-theft device, it is mainly locked ignition or start to achieve the purpose of anti-theft, at the same time with anti-theft and voice alarm.

GPS satellite positioning car anti-theft system is a network-based anti-theft device, it is mainly locked ignition or start to achieve the purpose of anti-theft, but also through the GPS satellite positioning system (or other network systems) sent alarm information and location of alarm vehicles to the alarm center.

No matter what kind of anti-theft mode, the car will alarm if open the car door or start the car without a key. That means the car will alarm or cannot be driven if I start the car with a phone without a key.

In order to solve this problem, I visited a car mechanic in my hometown. However, he was very busy this week, so I have to contact him next week.

Week 8

This week I found information online about how to install the WEMOS D1 mini into the car. I found this a very difficult step.

Now the biggest problem is that every vehicle has a safety system, my car is no exception. Car alarm is installed in the car, used to increase the difficulty of car theft and extend the theft time.

Most anti-theft system of high-end car are very complex. They include:

  • A complete set of sensors, including pressure sensors, switches, and vibration detectors, etc. A siren, often able to create a variety of sounds so that you can pick a distinct sound for your car.
  • A siren, usually able to create a wide range of even sharp sounds so that you can clearly hear the car’s alarm.
  • A backup power supply ensures that the anti-theft system can work even if the mains is disconnected.
  • A microcomputer that monitors the status of each sensors.

Microcomputers in most advanced systems are actually the brain. The job of the brain is to turn the alarm switch off and on such as the horn, headlight or installed siren when certain sensors detect an abnormality. The main difference between safety systems is that sensors and various devices are connected to the microcomputer in different ways.

Week 6

During this week, Todd guided me on how to get the WEMOS D1 mini into a server. I made the WEMOS D1 mini link the Newsimland and use MQTT as a carrier of information transmission. At the beginning, I do not know what is MQTT, so I search it on google. MQTT (Message Queuing Telemetry Transport) is an instant messaging protocol developed by IBM that supports all platforms and virtually connects all networked items to the outside world and is used as a communication for sensors (such as makes a home into networking through Twitter) protocol.


This application is very simple, only one page, including two buttons and the name of applications.


I found in the site click the ON button to enter page, click the OFF button to enterhttp:// page, through this method to control the LED, so I just need set the corresponding link for both buttons. I’ve injected two links into my application and hidden it. 

Next, I added logic in two keystrokes and two links.

Access on_web when ON button is pressed.


Access off_web when OFF button is pressed.


No error after I use the testing tools in this website, so I built this application and installed in my phone.

Finally, I successfully used this application to control the LED.