DIY k line adapters. Universal USB adapter K-L line BM9213 for tuning a car's injection engine. K‑LINE: A new look at familiar things

As is known for diagnostics on modern auto use a connector OBDII. This connector contains a digital bus from which you can read the necessary data. There are many protocols for this digital bus; they differ depending on the generation and brand of car. I use K-Line tire. In order to connect USB port A computer with a diagnostic connector needs a converter adapter. This is the adapter I decided to assemble.

To begin with, I purchased the long-needed parts.

I decided to assemble according to the standard scheme, of which there are plenty on the Internet. I just adjusted it a little for myself:

Next comes the usual process of laser ironing technology. The FT232RL microcircuit used has an SSOP28 package, in which the distance between the legs of 0.25 mm will force you to be careful. Experience in etching printed circuit boards with LUT will allow you to achieve this. I get tracks 0.12mm thick.

The toner is already on the copper base of the board. Ready to pickle

The etching process is completed: excess copper has been etched away.

Everything is ready for tinning and soldering parts

And here is the finished adapter with soldered parts. Judging by the photo, the size of the device turned out to be flash.

The adapter was given the following task:

• develop a reliable device adapted to our harsh climatic conditions;
• provide protection personal computer from interference on-board network car;
• ensure reliable communication between the computer and the car;
• provide versatility for connecting the adapter to vehicles that support K-line diagnostics.

The USB bus was chosen to interface with the computer, since it is currently the most common and provides power to the adapter. The FT232RL microcircuit from FTDIchip was chosen as a USB driver. This chip requires only a few external elements for its operation and provides any transmission speed without additional settings. This is very convenient, since diagnostic protocols use a non-standard baud rate. Below is block diagram of this microcircuit. It shows that all the necessary elements for the operation of the microcircuit are inside.

To connect the FT232RL chip you only need a few capacitors. Typical scheme connection is shown below.

To pair with car tire K-line (ISO9141-1, ISO9141-2, ISO14230) the L9637D chip from ST Microelectronics was selected. This microcircuit has a number of advantages compared to analogues:

• wide range of input voltages (4.5 - 40 volts);
• protection against polarity reversal;
• output current limitation via K-line;
• temperature protection;
• protection against impulse interference;

Below is a block diagram of the L9637D chip.

The L-line in the adapter is implemented using two transistors and is controlled using the RTS signal. As you know, the L-line is unidirectional (information comes from the computer, in our case, to the ECU), but the L9637D chip has an input for the L-line (this chip is intended for installation in the engine control unit and therefore the L-line here has an input function) . Therefore, the LI input here is used to read data from the L line. The data input is connected to the CTS signal. This creates another K-line.

To protect the adapter and computer from pulsed high-frequency interference (of which there is a dime a dozen in the on-board network of a car), filters called “ferrite beads” are used. These filters are manufactured by Murata. The adapter uses filters like BLM21PG331SN1. These filters when fed to them DC voltage have a resistance of about zero, and when a high-frequency signal is applied to it, they increase their resistance to 330 Ohms, thereby preventing the passage of high-frequency interference. In the diagram they are indicated as inductors (L1 - L3).

From all of the above, an adapter circuit was developed (shown below).

The power supply for the FT232RL and L9637D microcircuits is taken from the USB bus, and the K-lines are pulled up from the vehicle’s on-board network. Also included in the adapter circuit is a voltage regulator L78L05 to convert 12 volts to 5. This is done so that you can change the pull-up of the K-lines: 12 or 5 volts. Five-volt K-line signal levels are used in blocks where the ALDL protocol is used - these are GM blocks and January-4.

To ensure the adapter's versatility, it uses a DB-9 male connector. Cables with the corresponding diagnostic connectors. In this case, having one adapter and a set of cables, you can diagnose the entire range of cars diagnosed via the K-line.

IN this diagram The adapter also includes the ADM1485AR converter. It is designed to connect devices with RS485 interface.

When developing the adapter, only SMD components were used, so the board turned out to be compact. The board easily fits into the GC-9 adapter housing. The board layout is shown below.

The pinout of the connector for connecting cables is shown below.

This is what the finished soldered adapter looks like without a housing:

There are many K-LINE adapter diagrams on the Internet. Available on COM, available on USB. The simplest circuits are on COM, but nowadays this is not convenient due to the lack of this port on laptops. USB circuits are a little more complicated. Microchips are used there, but they still need to be found. In addition, you need to make printed circuit board. Therefore, I decided to do it in a simpler and more accessible way for everyone, using a data cable from old phones. Many people have this lying around in their back drawers.
We will need:
USB data cable from old phones (I used from Samsung c100/c110)
Radioelements (see diagram)
Soldering iron (and everything that comes with it)
Computer and some software

K-LINE adapter diagram

We assemble the diagram as conveniently as possible. We make a printed circuit board, or use a breadboard, or just a surface-mounted one (I chose the latter). Transistors VT1 and VT2 can be found in junk computer unit power supply, or buy it at a radio parts store, like everyone else. Diode VD1 - any rectifier with a low voltage drop. If you are sure that you will not mix up the plus and minus wires when you use them, you don’t have to install a diode. Capacitor C1 is also not particularly important, it protects against interference.
Once we have assembled the circuit, we move on to the data cable. First, install the PL2303 driver for it. Be sure to support non-standard speeds. (Download driver) After installing the driver, connect the cord and make sure it works. It should appear in Device Manager.

We remember what COM it is installed under.
Next, download the B&B COM test program (Download) to check the port.

Program

Data cable

We disassemble the data cable connector on the phone side and unsolder it. Now we need to determine which wire is which. To do this, connect the data cable to the computer, launch the program, select the appropriate COM port in it, any speed. Usually the black wire is negative. It should “ring” to the USB connector body. Next, use a voltmeter to find the wire on which +3.3 volts. Measuring this voltage, we try to write something in the program window. If the voltage changes, then it is the TxD pin. Now we try to connect this wire to the remaining two wires (no need for minus). When connected to the correct wire, the entered information will be duplicated in the lower program window... which means this is RxD. Wires found. Now we solder these wires to our circuit. Before turning anything on, make sure there are no short circuits in assembled circuit or breaks (the wire accidentally came off). Check compliance with the diagram.

We check the functionality of everything we have collected. Again, use the same program to connect to the port, but do not forget to supply 12V power. The information entered in the upper window should be duplicated in the lower one. If this happens, then the circuit is working. Can be connected to the ECU.

OBDII connector

Download the OpenDiagFree program for diagnostics. In the settings, select our port and switch to the “Method 2” connection. We use it)

If you want to indicate the operation of the diagnostic cable, just solder the LED with a resistor, according to one of the options listed below. In the first option, the LED will always light up while the adapter is connected to the diagnostic connector. It will blink while data is being transferred. In the second option, the LED will only blink when transmitting data, and is turned off the rest of the time.
We select resistor R8 at least 470 Ohms. It is advisable to have an even higher value so that there is no effect on the K-line signal.

LED connection options

Note:

If you still have problems with the port speed, then try adjusting the values ​​in the ExtBaudrate registry.

At the request of some readers, I decided to post what is probably the simplest one K-line adapter via COM port (in this case USB is not an option). This is excellent and proven adapter, its advantages; cheap, simple and can do a good job of picking the brains of your car. In this case, only the K-line is taken, we don’t need the L-line.

The adapter itself is assembled using only two transistors, here the diagram is simpler you won't find...

First I made a test version of the K-line adapter

So to speak, I started with experiments on a breadboard, collecting everything haphazardly, the main thing was that it would hold and the parts fit, some parts were missing, for example, instead of a capacitor o.47 uF I installed 220 nf, but in parallel... and so on.

I took the variable at 500 ohms, this is what a miracle board turned out to be at first

Well, we need to check the functionality of this device...

How to check the adapter without connecting to the car?

So first, download the software Check It 3.0

We connect our adapter to the computer and supply 12 volts to it. We do it exactly in this sequence, otherwise you can burn the Som-port. We do not connect the K-line itself, since we did not connect to the car.

The interface is DOS-like, press any button and press). Then - “skip”. Again we press any button and lo and behold)
We get to the menu, where by random method (trial and error - intuitively) we find test\serial ports\com1

Then press Enter

The port will be tested, if, of course, you assembled everything correctly. First, the test will run at a speed of 300 bits per second, then 1200, 4800, 9600, in short, all speeds will be tried.

here is an example of a test at a speed of 300 (bit/sec)

If the test passed at speeds of 300 and 1200 bits (baud), this is enough for our adapter to work normally.

If the test fails, a window like this will pop up...

This indicates that the adapter is assembled incorrectly or there is no power to the adapter. Well, okay, the test is over (it was so informative, one might say) now let's move on to the working version of the adapter.

Working version of the K-line adapter

All we need...

Parts List:

• transistors: KT315 or S9014 (2 pcs)
• 3 kOhm resistors (3 pcs) are R2, R3, R6 and 10 kOhm (2 pcs) are R1, R5
• Any LED will do (if not, don’t install it at all)
• any low-power diode like 1n4148
• 470 uF condenser, as well as a terminal block and a DB9 connector

First we draw a signet in Sprint...

2. We print several designs on a glossy printer to choose a good one. All options were normal - we make three seals.

If there are any mistakes, we correct them with a marker. before etching.

Every car owner at some point is faced with the problem of diagnosing his iron horse, which suddenly stops starting and working normally. To solve this problem, most people use the services of car services, where a specialist with a miracle device can easily decipher the fault code of your car and help make qualified repairs.

What should a car owner do if the warning light on the dashboard of his car comes on? Check Engine”, but who does not have the time or money to pay a car service every time for diagnostics of his car. Of course there is a solution, this manufacturingk lineDIY adapter.

If you are the owner of a budget foreign car like Daewoo or Chevrolet, as well as any domestic car except for the latest models of 13-14 years that have a CAN bus, then to diagnose your car, a regular k line adapter for diagnostics, which you can assemble with your own hands, will be quite enough for you.

Currently, on the Internet you can find a huge number of k line adapter circuits for self-assembly designed to work via a COM port. Since this connector is currently not available on modern computers, circuits for assembling k line adapters without virtual COM port converters will not be considered in this article. If your PC has a COM port, you can download diagramsk line adapter for COM port.

Let's take a look at the build process DIY k line adapter for PC with USBports.

This diagram was collected and modified by the user Samokat Veterana.

For assembly we need:

Capacitors:

1) 100nF - these are SMD 1206 non-electrolytes (3 of them)

2) 4.7uF. x 10V - tantalum chip capacitor, powered from USB (can be used at a higher voltage value, use at a lower voltage value is unacceptable)

3) 10uF. x 16V - tantalum chip capacitor, powered from +12V side (can be used at a higher voltage value, use at a lower voltage value is unacceptable)

Any electrolytes from 4.7 µF to 100 µF can be used. Their task in this circuit is to filter out interference. Please note that the voltage should be no less than 10V and 16V, respectively.

Resistors size 0805:

1) 27 Ohm (2 pcs)

2) 270 Ohm (2 pcs)

3) 510 Ohm (2 pieces)

Chips:

Adapter circuit

Both adapters are factory assembled and have a one-year warranty.