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Forum Index : Microcontroller and PC projects : CMM2: Page Copying vs. Swapping

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Nelno

Regular Member

Joined: 22/01/2021
Location: United States
Posts: 59
Posted: 12:35am 28 Jan 2021
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  epsilon said  
  Quote  Yes, it does. This occurred to me also, since there's an OPTION command to modify the clock rate.


I was actually thinking that your assembly might have an external oscillator with incorrect frequency, but since the clock rate seems correct, that's not it.

Re your SD trouble, you are aware that the pins on the side of the SD socket very easily bridge against the metal cover, right? So easily in fact that at first, I didn't even realize they were supposed to be separate. I actually thought I was fixing the SD socket enclosure to the PCB.

Did you check the stability of the 5V supply and the current draw?


Yeah, I was thinking the same, like maybe there was an additional clock crystal in there, but it doesn't seem to be the case. I have a friend who just received a RetroMax so I will try to get her to check the copy timings on it.

For the SD card, yes, I think I at some point I had it bridging with the right-most pin (looking from the back), but I am pretty diligent when it comes to checking for bridges with my multimeter after soldering, especially for something as delicate as these micro SD card slots.

As far as I can tell, the way the insert detection works with these particular connectors is that the right-most pin (again looking at the connector from the back) is the insert detection. When the spring arm is pushed to the side of by the card, that pushes the right-most pin into contact with the metal cover and this is why the metal cover is connected to ground. When that connection is made,  (and the card is in the slot) then the right-most pin and the case will be bridged and the card is detected as inserted. This confused me at first as to why I was getting bridging until I took the thing apart, looked at the mechanism and closely examined the circuit board where the right rear pad connects -- that pad is connected to ground.

Some of this might be slightly different for regular size SD cards vs. micro SD, since the regular cards support write-protect and the micro SD cards do not.

What I haven't been able to find is any documentation on exactly the connector used in the RetroMax. The new ones I ordered were essentially the same with only minor changes internally to the locking lever grooves inside, but in no case have I been able to find a part number for them or a data sheet. Mostly I was looking at the data sheet for the cards and trying to understand the connector from that, but it's not quite the same.

I think the voltage is ok, too. The micro SD takes something like 2.6V - 3.2V (something like that, I don't remember exactly). What I'm seeing is a little low but I only have a MiniDSO pocket oscilloscope that has never seemed to report voltages well (it always normalizes the signal quickly and shows them at zero after a second or so... probably there's a way to change that behavior I haven't figured out yet). If I look quickly I think I'm seeing something like 2.4V there.

Thanks for the pointers though, I'll spend some more time looking at it tonight. I'm clearly just missing something, but it doesn't help that the 3 re-solderings of such delect pads have caused some damage to the traces. I repaired the one damaged trace I found last night, but I'm almost certainly missing something somewhere.
Edited 2021-01-28 10:37 by Nelno
 
Nelno

Regular Member

Joined: 22/01/2021
Location: United States
Posts: 59
Posted: 12:43am 28 Jan 2021
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  RetroJoe said  Have you tried a "factory reset"? (see doc excerpt below). I had similar SD card trouble once and a full reset fixed it.I would also try a different SD card.

Pin 40 can be used to completely reset the Colour Maximite 2 to its "factory default" condition. If that pin is connected to ground (ie, pin 39) on power up all options will be reset to their defaults and any program in flash memory erased.


I haven't, but I will try it. Thanks for the suggestion.

When I first received the Retromax the USB keyboard wouldn't work and I couldn't set the language / date / time at all from a keyboard. I managed to do it with a terminal connection, but eventually (after realizing there was a 4K option RAM powered by battery) I decided to pull the battery and that magically fixed it.

Then, when I replaced the first SD card, iirc I had to pull the battery at some point to get it working. I assumed in all of the handling I had somehow disrupted the option RAM.

However, I have tried pulling the battery since installing the latest micro SD card connector and that had no effect. I don't know what bridging pin 40 does, but I'll try it. Thanks.
 
Nelno

Regular Member

Joined: 22/01/2021
Location: United States
Posts: 59
Posted: 02:06am 28 Jan 2021
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What I'm getting now sounds exactly like cdeagle reported in his post here https://www.thebackshed.com/forum/ViewTopic.php?TID=12105&P=10#146498

He didn't have a Retromax, and whatever is wrong with mine is my own fault at this point, but the behaviors described are the same, right down to the periodic blinking of the SD card access light (which I am pretty sure are periodic attempts to get the card to respond once it's detected as inserted).

Unfortunately, his was fixed by a return and it doesn't look like the root cause was ever determined.
 
TassyJim

Guru

Joined: 07/08/2011
Location: Australia
Posts: 5867
Posted: 02:35am 28 Jan 2021
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I can't offer any solution to your main problem but I do have an update on the PAGE COPY timing

Running this program:
mode 1,8
timer=0:page copy 0 to 1:?timer
timer=0:page copy 1 to 0:?timer

mode 1,12
timer=0:page copy 0 to 1:?timer
timer=0:page copy 1 to 0:?timer

mode 1,16
timer=0:page copy 0 to 1:?timer
timer=0:page copy 1 to 0:?timer


beta 7 firmware:
2.065
3.332

27.067
25.86

15.52
15.278

beta 8 firmware:
2.48
3.941

42.125
43.437

19.769
19.768

beta 9 firmware:
2.481
3.95

42.132
43.392

19.766
19.779

I didn't go back any further.

The beta7 firmware had struck a sweet-spot.
Hopefully, it can be found again.

Jim
VK7JH
MMedit   MMBasic Help
 
Nelno

Regular Member

Joined: 22/01/2021
Location: United States
Posts: 59
Posted: 02:56am 28 Jan 2021
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  TassyJim said  I can't offer any solution to your main problem but I do have an update on the PAGE COPY timing

Running this program:
mode 1,8
timer=0:page copy 0 to 1:?timer
timer=0:page copy 1 to 0:?timer

mode 1,12
timer=0:page copy 0 to 1:?timer
timer=0:page copy 1 to 0:?timer

mode 1,16
timer=0:page copy 0 to 1:?timer
timer=0:page copy 1 to 0:?timer


beta 7 firmware:
2.065
3.332

27.067
25.86

15.52
15.278

beta 8 firmware:
2.48
3.941

42.125
43.437

19.769
19.768

beta 9 firmware:
2.481
3.95

42.132
43.392

19.766
19.779

I didn't go back any further.

The beta7 firmware had struck a sweet-spot.
Hopefully, it can be found again.

Jim


Thanks, Jim. Those beta 8 and 9 times match what I was seeing exactly, at least I know my machine isn't at fault. Now to fix this pesky micro SD card connector...
 
matherp
Guru

Joined: 11/12/2012
Location: United Kingdom
Posts: 8516
Posted: 07:58am 28 Jan 2021
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There can be an issue with the SDcard where the card slot sits too high off the board so the card doesn't connect properly. This can be particularly the case when fitting a replacement slot to a board or using a 2nd use slot. Clean all solder off both the slot and the board using ribbon. Then make sure the slot is held tightly to the board as you solder the 4 case mountings
 
Nelno

Regular Member

Joined: 22/01/2021
Location: United States
Posts: 59
Posted: 03:34am 29 Jan 2021
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  matherp said  There can be an issue with the SDcard where the card slot sits too high off the board so the card doesn't connect properly. This can be particularly the case when fitting a replacement slot to a board or using a 2nd use slot. Clean all solder off both the slot and the board using ribbon. Then make sure the slot is held tightly to the board as you solder the 4 case mountings


I managed to fix it. All my fault for accidentally testing from the pad instead of the pin. In my attempt to keep the pins from bridging, two of them just weren't quite connected to their pads and when I was testing I was lazily resting the probe on the pad and not on the pin, so I kept thinking they were connected.
 
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