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Re: Own aduc7020 pcb design

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  • katagia
    ... I had no bigger problems with it. Maybe a silly question but have you checked every pin is soldered correct? The uC has no legs and distances are critical.
    Message 1 of 11 , Nov 12, 2008
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      --- In ADuC_ARM@yahoogroups.com, "pellepl" <pellepl@...> wrote:
      > anyone out there ever made a (working) pcb of their own with the
      > aduc7020 LFCSP package? The same which is on the minikit.
      >
      > I've successfully done some boards for the aduc7128 and 7129 lqfp
      > packages, which work smoothly. But for the 7020 the uC is more or less
      > dead. The internal clock seem to be alive, but all other IOs are high-z
      > on 2.7 volts.

      I had no bigger problems with it. Maybe a silly question but have you
      checked
      every pin is soldered correct? The uC has no legs and distances are
      critical.

      Do you have some protection layer over your copper lanes? Sorry, I
      don't know the correct english term for it. This could cause a gap
      between pcb and chip.

      In my first design I had problems with uart pins (bad contact) and I
      had to resolder them (I soldered the chip by hand).

      Everything else is fine? Pullup at reset, Pulldown at download and
      most important 470nF connected to LVdd?
    • pellepl
      ... less ... high-z ... you ... No questions are silly in this context - in fact, I hope the problem is silly so it will be easy to fix ;) Checked the pins -
      Message 2 of 11 , Nov 12, 2008
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        --- In ADuC_ARM@yahoogroups.com, "katagia" <TiloLutz@...> wrote:
        >
        > --- In ADuC_ARM@yahoogroups.com, "pellepl" <pellepl@> wrote:
        > > anyone out there ever made a (working) pcb of their own with the
        > > aduc7020 LFCSP package? The same which is on the minikit.
        > >
        > > I've successfully done some boards for the aduc7128 and 7129 lqfp
        > > packages, which work smoothly. But for the 7020 the uC is more or
        less
        > > dead. The internal clock seem to be alive, but all other IOs are
        high-z
        > > on 2.7 volts.
        >
        > I had no bigger problems with it. Maybe a silly question but have
        you
        > checked
        > every pin is soldered correct? The uC has no legs and distances are
        > critical.
        >
        > Do you have some protection layer over your copper lanes? Sorry, I
        > don't know the correct english term for it. This could cause a gap
        > between pcb and chip.
        >
        > In my first design I had problems with uart pins (bad contact) and I
        > had to resolder them (I soldered the chip by hand).
        >
        > Everything else is fine? Pullup at reset, Pulldown at download and
        > most important 470nF connected to LVdd?
        >

        No questions are silly in this context - in fact, I hope the problem
        is "silly" so it will be easy to fix ;)

        Checked the pins - handsoldered it also, it was some work. Made three
        boards with three different uCs, same result. Nice to hear that other
        people handsoldered it successfully also.

        Checked the pins with a microscope and tested the critical with a
        multimeter. I might have missed with the probes, but it seemed
        connected on the correct spots and disconnected on the wrong.

        Hmm, you mean soldermask? Yep, got that, but the microscope indicates
        everythings ok.

        The pullups and pulldowns are there, I was "inspired" by the minikit
        design - ripped it right off I did ;) That's what bothers me the most.

        I'll upload some schematics and gerbers soon enough in the file area.

        Thanks!
      • pellepl
        Created a photoalbum of the bad design. More stuff coming up here. http://groups.yahoo.com/group/ADuC_ARM/photos/album/946558215/pic/list
        Message 3 of 11 , Nov 12, 2008
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          Created a photoalbum of the bad design. More stuff coming up here.

          http://groups.yahoo.com/group/ADuC_ARM/photos/album/946558215/pic/list
        • paloalgodon
          ... I handsoldered mine, but used hot air, then retouched with an iron. Don t know the effects of leaving the solder slug underneath unconnected. I hope all
          Message 4 of 11 , Nov 12, 2008
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            --- In ADuC_ARM@yahoogroups.com, "pellepl" <pellepl@...> wrote:
            >
            > Created a photoalbum of the bad design. More stuff coming up here.
            >
            > http://groups.yahoo.com/group/ADuC_ARM/photos/album/946558215/pic/list
            >

            I handsoldered mine, but used hot air, then retouched with an iron.
            Don't know the effects of leaving the solder slug underneath unconnected.

            I hope all those vias in green underneath are all ground. I'd suggest
            that as an issue if not...

            Don't see anything else glaringly wrong, unfortunately.

            Steve
          • martin_schoenegg
            pellepl ... list We use to make longer pads so we are able to use a solder iron to heat the pad beside the IC. Our group made several layouts (even single
            Message 5 of 11 , Nov 13, 2008
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              pellepl

              > http://groups.yahoo.com/group/ADuC_ARM/photos/album/946558215/pic/
              list

              We use to make longer pads so we are able to use a solder iron to
              heat the pad beside the IC. Our group made several layouts (even
              single sided) without mayor problems. All hand soldered with a simple
              solder iron, no hot air or such specials. A few hints:

              Please do not connect or solder the metal surface on the bottom side.
              The mass of tin in the hole will easyly overheat your IC.

              Don't make wires nor vias under the chip. The metal surface is
              internally connected to GND and may give a short cirquit.

              Colophonium in alcohol is your friend for such handmade things. Use
              enough of such solution or an other flux to prevent shorts

              Good luck

              Martin
            • pellepl
              ... longer pads so we are able to use a solder iron to ... simple ... side. ... Hi, thanks for all tips! Using plain solder iron (and some wick) also. The vias
              Message 6 of 11 , Nov 20, 2008
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                --- In ADuC_ARM@yahoogroups.com, "martin_schoenegg" > We use to make
                longer pads so we are able to use a solder iron to
                > heat the pad beside the IC. Our group made several layouts (even
                > single sided) without mayor problems. All hand soldered with a
                simple
                > solder iron, no hot air or such specials. A few hints:
                >
                > Please do not connect or solder the metal surface on the bottom
                side.
                > The mass of tin in the hole will easyly overheat your IC.
                >
                > Don't make wires nor vias under the chip. The metal surface is
                > internally connected to GND and may give a short cirquit.
                >
                > Colophonium in alcohol is your friend for such handmade things. Use
                > enough of such solution or an other flux to prevent shorts
                >
                > Good luck
                >
                > Martin
                >

                Hi,

                thanks for all tips!

                Using plain solder iron (and some wick) also. The vias and wires
                under the chip are GND so a short should not cause any problem.
                Rechecked and remeasured everything, the only thing I can come up
                with is that I've heated the ADuCs too much/long. The hole was never
                filled with tin. I'm using 280 celcius on the iron - what temp are
                you guys using?

                I'm thinking of redoing the PCB using a bigger board with less
                constraints. Just to see if I can get the processor to kick in.

                Thanks / Peter
              • martin_schoenegg
                ... never ... My Weller Magnastat prefers 370 °C and I never had any problems with this. It may be better to solder quick and hot than too cold and needing
                Message 7 of 11 , Nov 21, 2008
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                  > with is that I've heated the ADuCs too much/long. The hole was
                  never
                  > filled with tin. I'm using 280 celcius on the iron - what temp are
                  > you guys using?

                  My Weller Magnastat prefers 370 °C and I never had any problems with
                  this. It may be better to solder quick and hot than too cold and
                  needing longer, but only as long as you use very little tin. The most
                  important thing may be a high quality solder tip.
                  BTW I prefer for prototyping the cheapest colophonium based Pb-tin
                  with 1mm diameter ;-)

                  Regards
                  Martin
                • pellepl76
                  Answering my own question as I found the problem some long while ago - stupidly enough I d forgot to tie the JTAG pins high. Duuuh.... Cheers / P
                  Message 8 of 11 , Nov 28, 2010
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                    Answering my own question as I found the problem some long while ago - stupidly enough I'd forgot to tie the JTAG pins high. Duuuh....

                    Cheers / P

                    --- In ADuC_ARM@yahoogroups.com, "pellepl" <pellepl@...> wrote:
                    >
                    > Hi,
                    >
                    > anyone out there ever made a (working) pcb of their own with the
                    > aduc7020 LFCSP package? The same which is on the minikit.
                    >
                    > I've successfully done some boards for the aduc7128 and 7129 lqfp
                    > packages, which work smoothly. But for the 7020 the uC is more or less
                    > dead. The internal clock seem to be alive, but all other IOs are high-z
                    > on 2.7 volts.
                    >
                    > Anyone? I'll gladly share gerbers or eagle-files ;)
                    >
                    > Cheers / Peter
                    >
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