logo elektroda
logo elektroda
X
logo elektroda

Tablet as a car's multimedia system

Maciejb2 66909 34
ADVERTISEMENT
Treść została przetłumaczona polish » english Zobacz oryginalną wersję tematu
  • Tablet as a car's multimedia system
    Hi,
    Over a year ago I made a multimedia system based on the Nexus 7 tablet. The goal was to create an interface that would provide many functions previously implemented by several devices. Assumptions:
    - Yanosik support on a large and clear screen and playing messages through the factory audio system,
    - Navigation - goals as above,
    - Playing your own songs and internet radio functionality through the factory audio set,
    - No cables or wires tangled in the cabin,
    - Minimal interference in ori radio,
    - The ability to easily disassemble the tablet.

    Designs of this type are becoming very popular, perhaps the following material will encourage some of the forum users to build such an interface. The car is a 2005 Honda Civic. The mechanical components are a purchased casing and a dock made of fiberglass and epoxy resin. The tablet can be charged / audio streaming to the radio via the docking connector located on the edge. Control of functions such as sound source, charging mode, reset are carried out via bluetooth (HC-05). In addition, the app on the tablet receives in the background information about the voltage of the installation, charging current and temperature of the converter.
    Tablet as a car's multimedia system
    Tablet as a car's multimedia system
    If the topic is of interest, I will provide more details. I estimate the cost of building the interface at about PLN 100, excluding the tablet and most of the components that came from my inventory.

    Unfortunately, I lost the file, so I'm uploading the video via the link:
    Link

    Cool? Ranking DIY
    About Author
    Maciejb2
    Level 11  
    Offline 
    Maciejb2 wrote 19 posts with rating 63. Been with us since 2008 year.
  • ADVERTISEMENT
  • #2 15765521
    Ba_rt
    Level 12  
    How did you "get along" with the original radio? Does it have an aux input?
  • ADVERTISEMENT
  • #3 15765616
    pawel1029384756
    Level 21  
    Made very nice, especially in relation to the design presented a few months ago, where a netbook was used. You followed the trend, why a display as a user can have a tablet and you did it really well.
    The possibilities for car diagnostics could be increased and then it would be a really nice toy.
    I am also curious how you connected the whole thing with the radio.
  • #4 15766041
    szwychtenberg94
    Level 9  
    Great idea. I would love to read more about the implementation of the entire project. I have been thinking about something similar for some time, but in Megan I. I was thinking mainly about using the raspberry pi, but thanks to your idea I can see that for little money you can build a nice system based on a tablet. As a colleague above writes - complete car diagnostics, that would be something. Congratulations on the performance.
  • #5 15766042
    bestler
    Admin of DIY, Automation
    What is this software on this tablet that can be seen with four windows? I am especially interested in internet radio, could you please share something like that? I have an android multimedia station and I would like to upload some nice radio, because unfortunately these Chinese stations have a poor tuner.
  • #6 15766173
    Anonymous
    Level 1  
  • ADVERTISEMENT
  • #7 15766788
    subribe
    Level 11  
    How did you make the exit interface from the tablet? These are some original docking pads, did you have to derive signals interfering with the structure of the tablet?
  • #8 15766824
    michalko12
    MCUs specialist
    subribe wrote:
    How did you make the exit interface from the tablet? These are some original docking pads, did you have to output signals interfering with the structure of the tablet?


    Is it really hard to find that in a few seconds you can have an answer using a search engine?

    Tablet as a car's multimedia system

    Source
  • #9 15767168
    Mscichu
    Level 18  
    I once wondered about a similar solution and came to the conclusion that the tablet display will not withstand high and low temperatures.
  • #10 15767230
    skaktus
    Level 37  
    eurotips wrote:
    ELM327 with BT module can be bought for $ 4 with shipping and you have engine OBD in almost every car.
    Only the reversing cameras are missing and in one tablet you included everything from the retrofitting package, I estimate it delicately at around 30,000 in a mid-range car.


    30,000? You exaggerated a bit. Today's cars for PLN 50,000 have what the author wanted :)
  • ADVERTISEMENT
  • #11 15767425
    wtełek1
    Level 14  
    Skaktus - but the author has obtained this at a much lower cost, and whether it will be stable, etc. As factory-made and reliable solutions, the test of time will show :)
    I would be tempted to do something like this because several tablets are damaged.
    I'm just wondering if it would be possible to add a flow meter or something for injection without much change. To calculate fuel consumption, average and instantaneous :)
  • #12 15767556
    Maciejb2
    Level 11  
    bestler wrote:
    What is this software on this tablet that can be seen with four windows? I am especially interested in internet radio, could you please share something like that? I have an android multimedia station and I would like to upload some nice radio, because unfortunately these Chinese stations have a poor tuner.


    I recommend http://ai2.appinventor.mit.edu/
    Tablet as a car's multimedia system

    There is a pulley that sips the link to the stream and allows you to play it. I think it is possible to share the entire project if there was such a need. By the way, the interface is inspired by the one that can be seen in the current generation of Jaguars :D
    Tablet as a car's multimedia system

    Added after 12 [minutes]:

    Ba_rt wrote:
    How did you "get along" with the original radio? Does it have an aux input?


    The radio did not have an aux - let me paste the description that I once published on another forum related to Civic. The description is a bit blatant, but I had in mind the users of that forum - not everyone has to be inclined to the technique.

    Pioneer OEM radio, I don't remember the exact version code, but I suspect that all variants have similar guts. There is no problem with the linear input in this equipment, but I will try to present the simplest and cheapest solution. At the beginning I would like to point out that it will not be possible to switch to the line input from the radio panel. The manufacturer used a 3-channel sound selector (only two are used: CD and radio), but the selector is digitally controlled by the main microcontroller. The selection of the 3 unused channel would have to be added to the code and the new soft uploaded to the radio. It remains for us to get to the radio track, the CD falls off for a simple reason - you would have to insert a CD to make the radio play at all. So to the point, we'll need screwdrivers, a soldering iron, side cutters, pliers, some cable, patience and basic soldering skills.
    After removing all possible screws, detaching the front panel clips (with them carefully) and removing the plates from the housing, we will see the following view:

    Tablet as a car's multimedia system

    The vertically standing module, marked in red, is a radio tuner, the arrow shows the area of our activities. One small difference - your tuner will still have the shielding plates on it. Desoldering them is not a small feat, but fortunately you won't have to do it - my innate curiosity told me. Nevertheless, side cutters + pliers will be needed to cut a small piece of sheet metal, which will make it difficult to access the place marked with the arrow. Don't worry, you can get rid of a fragment of the shielding, I don't have it at all and the radio is playing as it was. The main board of the radio is connected to the tuner with the help of short pieces of wire.
    Tablet as a car's multimedia system

    Our task will be to cut and desolder the wires responsible for the right and left sound channels from the tuner. The wires removed above have been replaced with cables, places described on the R and L PCB. In this case, the green and blue wires carry the signal from the tuner.
    Tablet as a car's multimedia system

    We do the same on the motherboard, the red and yellow wires are our line input. It will depend on us now whether we hook up our device there or connect yellow with green and blue with red and listen to radio stations again.

    All that's left is to derive the ground for our signal:
    Tablet as a car's multimedia system

    The black wire soldered between the two capacitors is our mass. You cannot see it in the picture, but underneath it there is a fairly thick path in the PCB - each component connected directly to this path is a potential mass donor. However, I would advise you to solder the leg of a large component or, like me, solder several components at once. The pads (legs) of the surface components are quite fragile, soldering a thick cable to a small chick is guaranteed to break the rain with the slightest movement of the cable.

    Finally, I would like to add that the easiest way to switch between the radio and auxiliary is on a double switch or on two switches - for the right and left channels.

    Regards

    Added after 7 [minutes]:

    Mscichu wrote:
    I once wondered about a similar solution and came to the conclusion that the tablet display will not withstand high and low temperatures.


    That is why it is "extractable". It would be a fear to leave him in the car in the summer in full sun.
  • #13 15767717
    jendrula60
    Level 12  
    Indeed, it begs to be expanded as a service computer for reading OBD, the problem probably with finding software for Android. Overall very cool
  • #15 15768581
    Maciejb2
    Level 11  
    szwychtenberg94 wrote:
    Great idea. I would love to read more about the implementation of the entire project. I have been thinking about something similar for some time, but in Megan I. I was thinking mainly about using the raspberry pi, but thanks to your idea I can see that for little money you can build a nice system based on a tablet. As a colleague above writes - complete car diagnostics, that would be something. Congratulations on the performance.


    It may be useful:
    The heart of the system is Mega8a. I used analog pins for:
    - temperature measurement of the tablet charging converter,
    - charging current measurement,
    - supply voltage measurement,
    additionally 3 pins led out to the connector - if you need to measure something else.
    The other IOs are mainly UART (HC-05) and relay control:
    - a two-contact relay for selecting the sound source,
    - relay which cuts off the voltage from the converter input (battery saving),
    - relay for switching between 5V (tablet charging) and 3.3V (the tablet thinks it is docked but consumes almost no current 12V) results in cutting off the converter. As is the too high temperature of the converter (Tcase = 110degC). A drop in the charging current from the typical value to about 1A means full charge, the voltage on the docking connectors is changed from 5V to 3.3V for about 2 hours. Disturbances are very important. The tablet does not have a separation between power and audio mass. The supply voltage should be taken from the radio harness - preferably from the connector itself. Generating long ground loops will punish us with severe whistles and the howl of the alternator in the loudspeakers. It is best to separate the audio and power grounds all the way to the docking connector. It is worth remembering that I have been struggling for 2 months with the emission audible in the loudspeakers. There is room for improvement - capacitance, input inductance - but not much if the mass is wrongly guided.

    I hope someone will find it useful.
    Greetings
  • #16 15769165
    h3c4
    Level 15  
    Hello..
    I had the same problems as my colleague above regarding interference from the converters powering my tablet - the worst thing was when the sound was turned off, and my circuit lacked the amplifier mute.

    Also, if someone starts building a tablet system, let him distribute the mass well, add filters, chokes, etc.

    As for OBD II on BlueTooth, I bought it on the website for diagnostics, but to be honest, these "OBD" are only suitable for showing the current operating parameters of the engine. Errors are not found (and there are proven AutoCom) because perhaps the software is too poor.

    My project made a year ago:

    Tablet as a car's multimedia system
  • #17 15769502
    andreee
    Level 24  
    Well, too weak functionality for me. The same gives me a 5.5-inch phablet hung on the glass and even more - because it also records my route with a camera. The cord is one power only. In addition, I have such a problem that in DCI engines I can change the ignition angles, erase computer errors, inspections, etc. My system also reminds me of the end of the inspection, insurance, and the need to change the oil ...
  • #18 15769557
    stanli
    Level 12  
    Congratulations on a successful project. There is also something missing in my car. If you could post a detailed description, I would be grateful.
  • #19 15769660
    Maciejb2
    Level 11  
    stanli wrote:
    Congratulations on a successful project. There is also something missing in my car. If you could post a detailed description, I would be grateful.


    Stanil, what would you like to know? The description of the app, connection to the radio and the most important parts of the diagram and description of the operation can be found in the answers above.

    Added after 10 [minutes]:

    pawel1029384756 wrote:
    Made very nice, especially in relation to the design presented a few months ago, where a netbook was used. You followed the trend, why a display as a user can have a tablet and you did it really well.
    The possibilities for car diagnostics could be increased and then it would be a really nice toy.
    I am also curious how you connected the whole thing with the radio.


    I once bought an ELM327 BT cube from China. I deleted a mistake several times with it. Average fuel consumption is displayed on the Civic in clocks. I read other data so rarely that I have not added such functionality yet. It can be done.
  • #20 15770044
    darres1
    Level 13  
    Maciejb2 wrote:
    Stanil, what would you like to know? The description of the app, connection to the radio and the most important parts of the diagram and description of the operation can be found in the answers above.


    Hello, a very interesting project, but I am not clear about the data transfer, the value to the tablet from atmega, for example: voltage measurement or any data and is it here?
  • #21 15770146
    Maciejb2
    Level 11  
    darres1 wrote:
    Maciejb2 wrote:
    Stanil, what would you like to know? The description of the app, connection to the radio and the most important parts of the diagram and description of the operation can be found in the answers above.


    Hello, a very interesting project, but I am not clear about the data transfer, the value to the tablet from atmega, for example: voltage measurement or any data and is it here?


    The HC-05 is hanging on the wall of the metal housing, tucked up to the UART of the atmega.
    Tablet as a car's multimedia system

    The tablet is the "master" in communication. Apka sends a request to HC-05 depending on the button pressed, etc. As I'm not a software eagle - request is in the form of a single character. After each character, the atmega sends back an echo if it has received a character that forces some mode of operation after a successful transition to that mode. If the received character is, for example, "V" - the state machine in response sends a string - containing the text representation of the voltage with the unit sign. Realizes that this is programming at the level of silt :D . Below is a fragment of the state machine on the atm:
    Code: C / C++
    Log in, to see the code

    Simple function that converts value from ADC to char [] and sends it over UART:
    [syntax=c]void SerialSendInt(int a)
    {
    char str1[5];
    char str2[4];
    char str3[3];
    if (a>=100)
    {
    unsigned int b = 0;
    b/=10;
    str1[2]=b%10+'0';
    b/=10;
    str1[1]=b%10+'0';
    b/=10;
    str1[0]=b%10+'0';
    for (uint8_t i=0; i=10)&(a
  • #22 15771965
    Mad Bekon
    Level 23  
    I am fighting something very similar.
    For me, according to the assumptions, it should be:

    Bluetooth sound
    USB reversing camera,
    USB flash drive input,
    Interface on the processor intermediating between bluetooth, CAN bus and Alpine DSP
    Internet access via an additional WiFi router

    As usual, something more important appeared in the course of action, but if someone here previously threw a picture of a tablet in the Golf, I will also contribute.

    Tablet as a car's multimedia system
  • #23 15772023
    Maciejb2
    Level 11  
    Mad Bekon wrote:
    I am fighting something very similar.
    For me, according to the assumptions, it should be:

    Bluetooth sound
    USB reversing camera,
    USB flash drive input,
    Interface on the processor intermediating between bluetooth, CAN bus and Alpine DSP
    Internet access via an additional WiFi router

    As usual, something more important appeared in the course of action, but if someone here previously threw a picture of a tablet in the Golf, I will also contribute.



    The frame turned out great. Made of a 2DIN frame? I also tried a webcam with my own access point - I have something like this in a sports webcam. However, the price effectively scared me away. What will you spend on CAN? HVAC emulation (air conditioning, air supply etc.)? My Hanka from before the ubiquitous CAN era. The entire center console is only electromechanics / mechanics and cables with CAN, I wouldn't do much of it there. :D
  • #25 15772580
    Mad Bekon
    Level 23  
    The frame is made of plywood, cut like the original frame on the outside, and inside it is matched to the Sony Tablet Compact. Tried with 2 din bezel but it didnt fit the tablet, the 2 din cutout was too small unfortunately the money for the bezel down the drain. Now the frame fits quite well, so I will replace it with laser cut plastic at the earliest opportunity.

    When it comes to CAN, I mainly mean steering wheel signals.
    I have already managed to capture them, now I have to fight the Alpine DSP interface.

    I tried to avoid USB connection at all costs and do everything wirelessly so that my tablet could be pulled out. There is no such cool connector as the NEXUS. Unfortunately, I couldn't find a wireless rear view camera without lag, so I'd rather put it there permanently and connect a USB HUB. Then maybe even the connection with the car will not be via bluetooth but via a USB-UART adapter. Then bluetooth will only be for audio.
  • #27 15777613
    Darekg
    Level 17  
    Well, I have to admit that the overall design is nice. Can you share the code from appinventor?
  • #28 15777650
    Maciejb2
    Level 11  
    Darekg wrote:
    Well, I have to admit that the overall design is nice. Can you share the code from appinventor?


    I was doing it a while ago. Textboxes and analog data reception went to the furnace, but I showed how it was done before, so it can be easily recreated. From what I remember the link to the RMF MAXX stream is dead for a few months, you need to find a new one.

    I'm uploading the entire project.
    Interfe...zip Download (3.5 MB)
  • #29 15781476
    bernanio
    Level 14  
    Maybe some of you were dealing with the DSP processor in something like this?
    I was also thinking about such a modification, but I care about the DSP.
    I know that you can leave the radio with the prock, connect with the aux, or via BT, but I rather mean eliminating the additional one. Currently, I use BT with the phone, but before it snaps and click on playback, sometimes I will get to my destination.
  • #30 15783108
    BigBoyPL
    Level 11  
    For those who are afraid to leave the tablet in the sun due to the temperature, I recommend looking at the matrix datasheet (CLAA070WP03).
    In fact, in 90% of devices on the market that have 7 "and a 1280x800 partition, this matrix or a compatible replacement also uses Chinese radios on Android.
    In addition, I can say that, for example, the 12.3 "displays used in new cars as a meter also do not have some super temperature parameters.
    In my opinion, the battery overheating may be a bigger problem, but I have not read the cell specifications yet.

Topic summary

The discussion revolves around the integration of a Nexus 7 tablet as a multimedia system in a 2005 Honda Civic. The user aimed to create a multifunctional interface that supports navigation, internet radio, and music playback through the factory audio system, while minimizing cable clutter and maintaining the original radio's functionality. Various responses highlight the project's design, including the use of a custom docking station made from fiberglass and epoxy resin, and the potential for car diagnostics using OBD-II protocols. Participants express interest in the software used for internet radio, the connection methods to the car's audio system, and the challenges of temperature management for the tablet. Suggestions for enhancements, such as adding a reversing camera and improving diagnostics capabilities, are also discussed.
Summary generated by the language model.
ADVERTISEMENT