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Thread: Interest check: Camry/Scion Steering Wheel Control -> USB

  1. #81
    Constant Bitrate MindDrive's Avatar
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    some real excellent fab work!!!! but just out of curriosity, why not just use an already built keyboard circuitboard and do tracebacks from each individual key?



    that way you could have basicly the same amount of buttons and control your keyboard has but integrated any way you see fit into steeringwheel controls...

    10 bucks http://www.tigerdirect.com/applicati...0181&CatId=142

  2. #82
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    Quote Originally Posted by MindDrive View Post
    some real excellent fab work!!!! but just out of curriosity, why not just use an already built keyboard circuitboard and do tracebacks from each individual key?



    that way you could have basicly the same amount of buttons and control your keyboard has but integrated any way you see fit into steeringwheel controls...

    10 bucks http://www.tigerdirect.com/applicati...0181&CatId=142
    output of 2-wire steering control is not discrete digital, but a range of voltages controlled by a resistor ladder.

  3. #83
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    board with ground layers, and rerouted VCC/GND


    I'll see about the enclosure.

  4. #84
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    You should change the way pin 1 and 2 of the screw terminal connects to the ground plane. It shouldn't be connected all the way around, it requires a lot of heat to solder a large copper surface like that and it's very hard to make a good solder joint there and it could possibly melt the plastic of the screw terminal because the pin is heated up much faster than the big copper surface which acts as a very good heat conductor. There should be space arounf pin 1 and 2, just like there is at pin 3, 4 and 5. Then just a vertical and horizontal trace across the pads. Look how the all the pads connects to the ground plane at the attached image, only 4 traces, 1 from each side. This is done so it's possible to solder and desolder this pad. The inside of the holes shouldn't be covered up either.


    You should also cover up a larger area around the X-tal, but not closer to the USB connector. Also move the X-tal a bit further down away from the USB connector, unless you have to make room for a screw hole in that area. For USB designs it's generally reccomended to keep the X-tal at the other end of the PCB as the USB connections.

    I don't know how much the USB connector reaches outside the edge, but still looks like you will have to move it further outside the edge to make is as long as the thickness of an enclosure (or shorten the PCB a bit and let the USB connector stay where it is.

    From C1 USB power to the LDO and from the LDO to C2 I would draw straight traces directly from the side of the LDO pads to the side of the C1 and C2 pads and fro the side of C2 to X1. This will improve decoupling because the copper traces from the LDO will to the circuit will pass right by C1 isnstead of around it and the same at C2. This will also get rid of the big copper area around D1 and C2 which makes soldering harder.

    Analog ground should only be routed to digital gorund (C2) through the analog decoupling capacitor C7 near the indcutor. The ground plane at pin 1 of the screw terminal should not go directly to C2. Doing this ruins the analog decoupling, instead the connection should be made from C7 to C2. So the AVCC to AGND current loop from the AVR + resistor ladder is properly bypassed by C5 as described in AVR042.
    I would move the the analog ground plane to the bottom (blue) layer.

    The same thing applies to digital gound. The GND connections from the AVR to C2 should not be taken from a via under the AVR, but directly at the other side of the C5 capacitor, so the digital DVCC to DGND current loop from the AVR is properly bypassed by C5 as described in AVR042.
    At the same time also remove the GND trace form the ISP connector to the via below the AVR and instead route it from the ISP at the bottom edge of the PCB over to the GND at the jumper. Just extend the ground plane at the X-tal to cover the area around the GND end of the jumper too.

    And speaking of the bootload jumper, wouldn't it be better to just change the bootlaoder source code to read PD5 (pin 9) instead of PD3 (pin 1)? This way you don't have to route a long trace for the jumper below the crystal to pin 1, but can just route it to PD5 (pin 9) right next to the jumper instead. Or maybe you prefer to keep the bootlaoder sorucecode unmodified?
    Don't know if you have already made other modifications to the bootloader soruce code? The bootlaoder is maintained by third party, so if you haven't modified anything else in the bootloader soruce code, maybe it's easier to just keep it intact so you don't forget to modify the pin assigment next time if you download a new version of the bootloader.
    The only thing that has to be changed in the bootloader.h sourcecode is the number 3 to 5 these three places maked with blue:
    Code:
    /* ------------------------------------------------------------------------- */
    
    /* Example configuration: Port D bit 3 is connected to a jumper which ties
     * this pin to GND if the boot loader is requested. Initialization allows
     * several clock cycles for the input voltage to stabilize before
     * bootLoaderCondition() samples the value.
     * We use a function for bootLoaderInit() for convenience and a macro for
     * bootLoaderCondition() for efficiency.
     */
    
    #ifndef __ASSEMBLER__   /* assembler cannot parse function definitions */
    #include <util/delay.h>
    
    static inline void  bootLoaderInit(void)
    {
        PORTD = 1 << 3; /* activate pull-up for key */
        _delay_us(10);  /* wait for levels to stabilize */
    }
    
    #define bootLoaderCondition()   ((PIND & (1 << 3)) == 0)   /* True if jumper is set */
    
    #endif
    
    /* ------------------------------------------------------------------------- */
    And as I mentioned earlier you should add some pin description text near each pin at the bottom (blue) layer at the screw terminal. This will get etched into the PCB so you can read it even though there's no silk screen at the bottom. It's nice to be able to read what the 5 different pins are for when you connect the wires.

  5. #85
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    Quote Originally Posted by Blues View Post
    ...And as I mentioned earlier you should add some pin description text near each pin at the bottom (blue) layer at the screw terminal. This will get etched into the PCB so you can read it even though there's no silk screen at the bottom. It's nice to be able to read what the 5 different pins are for when you connect the wires.
    new board


    ok, I rerouted the ground traces and fixed the ground planes. I left the AGND plane on the top layer because the purpose is supposed to be isolating the ADC lines.

    as for the bootloader, yeah, i forgot i could just change the bootload check pin description.. i'll have to think about that...

    lastly, i'm not sure how useful the names of the terminals on the bottom of the pcb is, but I suppose I could add it, its just that I was thinking about adding names last.

  6. #86
    Constant Bitrate
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    Move the via near the USB pad, it's short-circuiting your GND plane with the USB pad. Didn't the PCB software warn you about that?

  7. #87
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    Quote Originally Posted by Blues View Post
    Move the via near the USB pad, it's short-circuiting your GND plane with the USB pad. Didn't the PCB software warn you about that?
    oh.. oops. it did, but i think i moved it because the DRC complained about the restrict pad under the usb when i was moving it on the pcb.

  8. #88
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    ok fixed board...


    and BOM

  9. #89
    Constant Bitrate
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    You should move the ISP header further away from the AVR. Looks like the corner will touch bthe AVR. You silkscreen header has rounded corners. But the FCI header from your BOM does not have cut corners at the ends:
    http://search.digikey.com/scripts/Dk...me=609-3218-ND
    Attached Images Attached Images   

  10. #90
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    Just had a look at your BOM.
    You use a 3.% mm pitch screw terminal from Phoenix Contact ($0.82): http://search.digikey.com/scripts/Dk...me=277-1723-ND


    Digikey also offer a cheaper alternative from Tyco ($0.73): http://search.digikey.com/scripts/Dk...name=A98039-ND

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