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Forum Index : Microcontroller and PC projects : Hardware or Software Problem?

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toml_12953
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Joined: 13/02/2015
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Posts: 442
Posted: 10:00pm 27 Nov 2020
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I'm running MMBasic 5.06.00b6. Since I loaded it, the unit fails to boot occasionally. It displays the signon message at the top but the red LED doesn't come on and there's no caret prompt. The keyboard doesn't respond. I have tried several SD cards in case there was a problem with them but no change. There's almost a pattern to it. It usually starts OK twice then doesn't start on the third try, then starts OK twice, etc. This may be a coincidence. I didn't have this problem before b6 but this may be a coincidence, too. I figured I'd ask here before reverting to b5 to try it.
 
Womble

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Joined: 09/07/2020
Location: United Kingdom
Posts: 267
Posted: 12:25am 28 Nov 2020
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@toml_12953 ...
Try a different USBA-B cable.  That solved many problems for me, I was getting voltage drops powering the CMM2.  Once I tried a different cable all my problems vanished.
 
toml_12953
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Posted: 01:27am 28 Nov 2020
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  Womble said  @toml_12953 ...
Try a different USBA-B cable.  That solved many problems for me, I was getting voltage drops powering the CMM2.  Once I tried a different cable all my problems vanished.


Thanks! I'll try it but since the problem only started happening after I upgraded, I don't know if it'll work. It's worth a shot, though.
 
Turbo46

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Joined: 24/12/2017
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Posted: 02:20am 28 Nov 2020
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  Quote  Try a different USBA-B cable
and/or a different power supply.

Bill
Keep safe. Live long and prosper.
 
toml_12953
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Posted: 11:13am 28 Nov 2020
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  Turbo46 said  
  Quote  Try a different USBA-B cable
and/or a different power supply.

Bill


What voltage should the power LED be? I had to replace it and I only had a 5V 3mm LED in green. Could that cause a problem? I wouldn't think so but figured I'd ask anyway.
 
Turbo46

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Posted: 11:48am 28 Nov 2020
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An LED is not normally rated for voltage unless they include a series resistor. Usually they don't.

A green LED has a voltage drop of probably less than 2 volts and requires a series resistor to limit the current through it. Providing that you have the series resistor still in place and the LED is working there should be no worries.

Bill
Keep safe. Live long and prosper.
 
toml_12953
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Posted: 12:03pm 28 Nov 2020
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  Turbo46 said  An LED is not normally rated for voltage unless they include a series resistor. Usually they don't.

A green LED has a voltage drop of probably less than 2 volts and requires a series resistor to limit the current through it. Providing that you have the series resistor still in place and the LED is working there should be no worries.

Bill


No there is no resistor on the LED itself, nor on the activity LED.
 
Turbo46

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Posted: 12:18pm 28 Nov 2020
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This is a part of the schematic for the version using the Waveshare board. You can see that each LED has a 1k series resistor.




Here they are on the board.

If you have the non-waveshare board (as I do) they will be SMD resistors near the LEDs.

Bill
Keep safe. Live long and prosper.
 
toml_12953
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Posted: 12:36pm 28 Nov 2020
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  Turbo46 said  

This is a part of the schematic for the version using the Waveshare board. You can see that each LED has a 1k series resistor.


If you have the non-waveshare board (as I do) they will be SMD resistors near the LEDs.

Bill


So the fact that the LED is rated for 5V has nothing to do with the lockup at start?
Edited 2020-11-28 22:44 by toml_12953
 
Turbo46

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Posted: 12:54pm 28 Nov 2020
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No. If the LED is rated for 5 volts it MUST include a series resistor in the package. That would have the effect of reducing the current drain compared to a normal LED.

If it's working then that's not a problem.

Bill
Keep safe. Live long and prosper.
 
toml_12953
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Posted: 03:56pm 28 Nov 2020
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  Turbo46 said  No. If the LED is rated for 5 volts it MUST include a series resistor in the package. That would have the effect of reducing the current drain compared to a normal LED.

If it's working then that's not a problem.

Bill


Hmm. There's no resistor on the LED itself but the package says they're rated for 5V.
 
matherp
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Posted: 04:08pm 28 Nov 2020
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I use the 5V LEDs a lot - you can't see the resistor but something is there as they definitely current limit when powered direct from 5V
 
lizby
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Posted: 04:47pm 28 Nov 2020
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I have bought what are sometimes called "resistorized" LEDs which contain resistors which allow them to be plugged into breadboards directly off of microprocessor pins. I have a package from one set of them, and the part name ends with "5V".

The resistors are so tiny that I cannot see them without a magnifying glass.

I cannot see any way that this type of resistor (if that is what yours are, and if undamaged) could cause your CMM2 to fail.
PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed
 
toml_12953
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Posted: 05:55pm 28 Nov 2020
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  lizby said  I have bought what are sometimes called "resistorized" LEDs which contain resistors which allow them to be plugged into breadboards directly off of microprocessor pins. I have a package from one set of them, and the part name ends with "5V".

The resistors are so tiny that I cannot see them without a magnifying glass.

I cannot see any way that this type of resistor (if that is what yours are, and if undamaged) could cause your CMM2 to fail.


So far, I've tried three different USB cords and three different power supplies (in various combinations), two different SD cards and I finally removed the LED entirely. It still usually locks up on startup. I'm running out of ideas. Maybe I just got a lemon. I research everything I buy carefully and no matter how many thousands of glowing reviews of a product there are, when I buy one, I get one that doesn't work. This happens every time!
 
toml_12953
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Posted: 06:43pm 28 Nov 2020
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It's the software! just I reverted to 5.05.06r22 and the machine starts 100% of the time perfectly.

Whew! I don't know why no one else with 5.06.00r6 is having a problem but I sure was. Now if only I could find 5.06.00r5 again. I had no problem with that one either. The lockups started happening with r6. Is r5 still available somewhere?
Edited 2020-11-29 04:48 by toml_12953
 
Turbo46

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Posted: 11:06pm 28 Nov 2020
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  Quote  no one else with 5.06.00r6 is having a problem


Could I please suggest that you download a fresh copy of r6 and re-flash that? Sometimes (but not very often) things do go wrong.

Bill
Keep safe. Live long and prosper.
 
toml_12953
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Posted: 11:35pm 28 Nov 2020
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  Turbo46 said  
  Quote  no one else with 5.06.00r6 is having a problem


Could I please suggest that you download a fresh copy of r6 and re-flash that? Sometimes (but not very often) things do go wrong.

Bill


Well, well! the new copy of r6 I downloaded is loading properly every time. Thanks! I notice that on my system, STM32CubeProgrammer doesn't verify the download the way the CMM2 manual shows it will. Has the verification been eliminated from the current STM version?
Edited 2020-11-29 09:37 by toml_12953
 
Turbo46

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Posted: 11:43pm 28 Nov 2020
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You need to check (tick) the 'Verify programming' box before clicking on the 'Start programming' button. I think it stays selected for next time.

Bill
Keep safe. Live long and prosper.
 
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