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Forum Index : Microcontroller and PC projects : CMM2 - Maximite2 Kit v3.0 PCB build notes

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Womble

Senior Member

Joined: 09/07/2020
Location: United Kingdom
Posts: 198
Posted: 11:19pm 11 Aug 2020
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YaY Fixed  It

Many thanks Guys for all your help.

Following on from advice from Phil (WW) I went over my soldering, and reflowed all the joints and cleaned up any excess solder using desolder braid where I had been a little enthusiastic.  This had the benefit of ensuring there were no dry joints causing my problems.

However Rob hit the nail on the head.

  robert.rozee said  just had a thought - have you been using the same A-B USB cable throughout all your testing?


I had been using the newest and most heavy duty USB A-B cable I posessed.  Turns out this was a bad move.

Swap the cable and voila ...
no more noise,
silence when editing files,
no keyboard crashes,
4.96v / 3.3 v when using my "power bank battery",
and 5.03v / 3.3v when using my "2A USB Lenovo Tablet Power Supply".

I get similar results with every other USB A-B cable I own  

I feel a right muppet for overlooking this.



Regards

A Happy Womble
 
HellbentHorse
Regular Member

Joined: 08/07/2020
Location: Australia
Posts: 51
Posted: 12:34am 12 Aug 2020
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Congrats!

I'm sure we've all been subject to muppet-esque oversights before, all part of the learning process right!
 
Womble

Senior Member

Joined: 09/07/2020
Location: United Kingdom
Posts: 198
Posted: 12:40am 12 Aug 2020
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  HellbentHorse said  Congrats!

I'm sure we've all been subject to muppet-esque oversights before, all part of the learning process right!

Oh yeah, my feet are full of bullet holes  
Wombles have kapok for brains
 
Atomizer_Zero
Senior Member

Joined: 04/07/2020
Location: United Kingdom
Posts: 134
Posted: 01:25am 12 Aug 2020
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I'm glad you've finally worked it out. Now you can code in peace lol
 
bigmik

Guru

Joined: 20/06/2011
Location: Australia
Posts: 2370
Posted: 01:26am 12 Aug 2020
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Hi Womble,

Glad you found the cause...

Really I am stunned that the cable caused those issues.. I can understand the low voltage, there must be something funny with it for sure..

I have only found that they either work or they dont..  long ones and skinny ones are not generally the best to use.. (albeit the one I use is probably 1.5m (5ft) long and it is running from a USB3 hub that is fed by another 1m feed cable.

Kind Regards

Mick
Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<<
 
Womble

Senior Member

Joined: 09/07/2020
Location: United Kingdom
Posts: 198
Posted: 02:02am 12 Aug 2020
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  bigmik said  Really I am stunned that the cable caused those issues.. I can understand the low voltage, there must be something funny with it for sure..

I have only found that they either work or they dont..  long ones and skinny ones are not generally the best to use..

You and me both  
I had carefully selected the "Newest" and "Fattest" cable I had.
It was a known good printer cable approx 1M long.
I had considered the cable "girth" and reasoned that a "fat one" would have nice heavy duty conductors.  

It never crossed my mind that it might be the USB A-B cable.  
Until Rob stepped in heroically  

I had assumed it was "assembler" error on my part, or perhaps a duff Waveshare or other component.  The number of times I went over my soldering, and checked voltages and went looking for short circuits with a multimeter.

I can certainly see why manawyrm specified USB-C for the power cable on his  "Clone CMM2 PCB".  That connector is designed for charging, and to supply power to devices.

Regards

A (now) Happy Womble
 
robert.rozee
Guru

Joined: 31/12/2012
Location: New Zealand
Posts: 1640
Posted: 05:04am 12 Aug 2020
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it was just a process of elimination - i do hope no one was offended as we worked through the list starting at the most probable, working down to the most unlikely. unfortunately, when searching for the root-cause of an issue it is often necessary to ask 'hard' questions, and repeatedly asking them until there is a definitive response.

as an aside, try taking a magnet and see if the 'defective' USB cable is attracted to it; i have come across cable from china that is made using steel wires that are copper plated.

geoff, peter: might i suggest that checking the 5v rail, between the shell of the keyboard USB socket and the contacts of the power switch, be placed at the top of the list of troubleshooting tips? there may be quite a few USB A-B cables out there waiting to cause CMM2 problems.


cheers,
rob   :-)
 
Womble

Senior Member

Joined: 09/07/2020
Location: United Kingdom
Posts: 198
Posted: 12:44pm 12 Aug 2020
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  robert.rozee said  it was just a process of elimination - i do hope no one was offended as we worked through the list

Not me, I'm just A Happy Womble now that I have a fully functional CMM2  
 
Womble

Senior Member

Joined: 09/07/2020
Location: United Kingdom
Posts: 198
Posted: 01:06pm 12 Aug 2020
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  robert.rozee said  geoff, peter: might i suggest that checking the 5v rail, between the shell of the keyboard USB socket and the contacts of the power switch, be placed at the top of the list of troubleshooting tips? there may be quite a few USB A-B cables out there waiting to cause CMM2 problems.

I agree, also checking the voltage between the USB-B shell and the 5VIN, 5VOUT, and 3.3V pins on the Waveshare was particularly useful to confirm that things are good once you have the CMM2 running initially.
 
64kram

Newbie

Joined: 02/08/2020
Location: United Kingdom
Posts: 2
Posted: 07:07pm 15 Aug 2020
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Hi All, just wanted to say a quick thank you for the information in this thread, it's likely saved me a fair few hours!

My CMM2 kit arrived this morning and coincidentally I have the same v3.0 PCB model and Waveshare board (from the same Ebay source) as Womble. For my first attempt at soldering I'm overjoyed that everything appears to be working, thanks largely to the details provided here. However I do have the dreaded screen tearing issue, so looks like there's still some work to do!

Fantastic product and project. Looking forward to contributing in the near future!
 
Womble

Senior Member

Joined: 09/07/2020
Location: United Kingdom
Posts: 198
Posted: 07:25pm 15 Aug 2020
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  64kram said  Hi All, just wanted to say a quick thank you for the information in this thread, it's likely saved me a fair few hours!

My CMM2 kit arrived this morning and coincidentally I have the same v3.0 PCB model and Waveshare board (from the same Ebay source) as Womble. For my first attempt at soldering I'm overjoyed that everything appears to be working, thanks largely to the details provided here. However I do have the dreaded screen tearing issue, so looks like there's still some work to do!

Fantastic product and project. Looking forward to contributing in the near future!

Well done with the soldering, and welcome to the community.

If you have screen tearing, the fix is the Oscillator Mod.  I posted the parts I used earlier in this thread.  The official RS part numbers are also in the "Construction Guide".  There are also posts on this thread about how to approach fitting the mod.

Regards

Womble
 
robert.rozee
Guru

Joined: 31/12/2012
Location: New Zealand
Posts: 1640
Posted: 01:34am 16 Aug 2020
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  Womble said  
  64kram said  However I do have the dreaded screen tearing issue

If you have screen tearing, the fix is the Oscillator Mod


BEFORE doing the oscillator mod, please (a) check the 5v rail (between USB keyboard socket metalwork and back of power switch) and (b) try a different USB A-B cable for the power. i have a sneaking suspicion that bad power may also have something to do with the crystal oscillator on the waveshare module nor running reliably.


cheers,
rob   :-)
 
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