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  1. @quorten well done. One thing you can so is run the AVR from the built in oscillator (8Mhz down to 256khz if I remember), much, MUCH quicker than 32k -- you can still use the 32k crystal as timing reference for one of the timer so it stays accurate, but will have a lot more cycles to do the rest.
  2. Cool, with simavr you can trace the exact time the interrupt is /raised/, so you can see what the delta raise vs pin toggle occurs. Altho, in your interrupt handler for the pin toggle, perhaps you shoudl re-enable the interrupt JUST after the toggle (in fact, you can do it on the /previous/ line as the reenabling takes 2 cycles), the rest of the expression (checking the pin value) can be done with interrupt enabled in the handler, it's not critical. -- since it's 32 bits operation it takes quite a few cycles on the AVR.
  3. @Kai Robinson I couldn't find the RTC chip on the schematic. Do you think the 65C22 has internal pullups? @quorten I noticed you enable/disable interrupt in various places in the firmware, in some place I don't think it's actually necessary to do so (when reconfiguring ports for example) -- it's possible that the 'stretching' that occurs is because the interrupt is delayed by one of these blocks. You could see if it's the case by tracing the interupt generation vs the interrupt delivery. What sim are you using?
  4. Couple of question here: is there a pullup resistor on the board for the data line? If so, you probably should not /drive/ the pin as an output, but configure it as open drain, this is pretty much to ensure both end are not driving the pin at the same time (which would damage both drivers). Also, for the clock pin, I notice it is also INT0 as well as PCINT2 on the AVR, so you could use an interrupt vector for that, and put the AVR to sleep in between. Rigth now the AVR runs full speed all the time to resample the clock signal. /Ideally/ you would put the CPU to sleep /all the time/ and le
  5. Right, I've added a bit of sponsorship to @Kai Robinson for my wall-board, if anyone else feel like helping, remember you would be hard pressed to find something you would hang on your wall for less than £30 Also, on a side topic regarding the attiny85 RTC chip, I'm the author of https://github.com/buserror/simavr - I can simulate pretty much any AVR firmware with simulated external input before you have to flash it and put it on a board, if anyone needs a bit on support getting that working, feel free to ping me.
  6. Actually I'd like to do the same, ie buy a dead board to support this awesome project :-) Also in the UK, PM if if suitable.
  7. Thanks for the tip. I had a poke around; probe on the ground pins at the connector, and measured resistance at the + of all the SMT caps, radialy. And yes /most/ of the board reads about 16 ohms -- give or take -- , but around the 74hcs I have replaced, it reads 3ohms on the VCC... I removed the SOICs, and my patches, and it still the same, so I suspect a short in the existing traces somehow. But it seems /pretty clear/ the short is around these parts... I wonder what it could be. tomorrow I'll look under the board and see if I can find another 3 ohm reading, if not, at least it l
  8. So well, not so good as it turns out. As soon as I slotted the batteries in I heard a little "click" noise from the part of the board near the power button or thereabout. Removed the batteries of course... I got investigating, and there is a short on the main rail! Almost everywhere... that annoyed me a lot as I was very careful but then again... small mistake? So I started to remove all the caps I replaced (well the SMT ones, I can't see the bigger ones being a problem!) and test until none was left and... no luck, still shorting. So I think I'm going to al
  9. I'm currently doing the same job, and I decided outright to change UB1 and UB2 -- make sure ALL the traces connect while the chips are off the board, as on my board, some of the traces between UB1&2 were corroded enough to remove connection between pads. Also check on the power button side, as there was quite a bit of damage there, I decided to change the SCC ICs there as well as they were badly corroded. I've been fixing another problem with another piece of kit so I ahven't had time to power mine up yet, but I hope I can do that in the next few days!
  10. Anyway, project still ongoing, as I had quite a few other thing to do recently. However today I did 'recap' the whole board, and I just have to re-install the SOIC14 x4, then add a couple more wires (for failed traces on the pads there). I only have one worrying trace I can't do anything about unless I remove one of the 10000 pins big IC, and I won't do it unless it fails to start! I checked under the SIMMS, under the ROMs and well everywhere I could, and I hope its now acidicaly 'stable'. Also, I took the PSU appart and it genuinely look pristine, the caps have no
  11. Ok so today I did another run at the Mac II, discovered a couple of extra traces that were cut (some are quite subtle!!) near the power switch. I ended up cleaning the thru hole cap holes with the tiniest drill bits and that was a lot less stressfull than all the other attempts and methods I tried. I don't know what I'm doign wrong, but no amount of heat. So I've now reinstalled the big caps, and the battery holders. I still need to do another inspection, then wil be re-solderring the SOIC14's, then I have a couple of extra patches to add for traces that are cut /under/ these SOIC footpri
  12. Where's the +1 button around here Thanks @Michael_b and @blusnowkitty
  13. Ah good tip, in fact, excellent idea! I also have hot air so I'll try that next. I've been sulking for a day or so because of that problem so it gives me "options"
  14. I got 2 of 3 of these, I even have the 'heated tip' one... doesn't help much. I think I'll have to try the "iron heating one side of the board, pump on the oher side" and see if that helps..
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