Character Display possible issue.

Discuss suspected bugs with other users and Sim Innovations Staff

Moderators: russ, Ralph

Message
Author
User avatar
Ralph
Posts: 7878
Joined: Tue Oct 27, 2015 7:02 pm
Location: De Steeg
Contact:

Re: Character Display possible issue.

#21 Post by Ralph »

I haven't followed any of this, so I'm completely clueless :)

User avatar
jph
Posts: 2846
Joined: Fri Apr 10, 2020 12:50 pm
Location: Somewhere over the rainbow..

Re: Character Display possible issue.

#22 Post by jph »

Keith Baxter wrote: Tue Jan 04, 2022 2:10 pm
jph wrote: Tue Jan 04, 2022 10:08 am
Very neat ! - I like the online version.
I use Labcentre Proteus as it has a full schematic and pcb design, but, also has a complete circuit emulation with virtual test equipment so that once you have done the schematics you can actually RUN the complete circuit on the PC - in real time
Joe
Hi,

So I guess I will be sending you my MAX7219 PCB,s to run on Labcentre Proteus then :lol: :lol: :lol:
Might be a good exerciser.

Did you buy and try just the MAX7219 chip? I am not talking about unsoldering a chip from a board, A new one. !!
Keith

@Ralph Whilst still on topic. I do not mind if some of these posts are moved to the other thread. Up to you guys.
Hi Keith, I have both DIP and SO versions on various devices of various ages - such as some of these boards and plenty of the dot matrix display (the 8x8 units). I used both to test. I will have a batch of 10 arriving (complete 8 display units in a couple of weeks (the cheapest ones - or near enough) to test in longer strings / chains. It will be extremely interesting to look at the scope signals with, say, 5 devices chained. I only have a 2 channel scope, it is times like this a 4 channel would be better but it is perfectly adequate. It is definitely better to run your traces carefully and these boards a certainly not optimised !, and that is being kind. However, if a single easy 'fix' can be done - as in ringing the clk / gnd etc then great. Will see, it is good to dust of the scope. Thinking about it, I do have an 8 channel data analyser as well so can use that. We will see, but at least looking at the actual signals will tell us a lot. Anything learnt from that could, if necessary be implementing in a board layout if necessary. These boards have 'been around the mill' as they have been around so long and the net is not full of issues so it is easiest in the first place to simply test them with the right equipment and see where and what may be happening.
It is all good fun. I can then post the results here.
Joe. CISSP, MSc.

User avatar
jph
Posts: 2846
Joined: Fri Apr 10, 2020 12:50 pm
Location: Somewhere over the rainbow..

Re: Character Display possible issue.

#23 Post by jph »

Ralph wrote: Tue Jan 04, 2022 2:25 pm I haven't followed any of this, so I'm completely clueless :)
:lol: @Ralph
That doesn't entirely translate 100% :D
Joe. CISSP, MSc.

User avatar
jph
Posts: 2846
Joined: Fri Apr 10, 2020 12:50 pm
Location: Somewhere over the rainbow..

Re: Character Display possible issue.

#24 Post by jph »

jph wrote: Wed Jan 05, 2022 6:55 am
Keith Baxter wrote: Tue Jan 04, 2022 2:10 pm
jph wrote: Tue Jan 04, 2022 10:08 am
Very neat ! - I like the online version.
I use Labcentre Proteus as it has a full schematic and pcb design, but, also has a complete circuit emulation with virtual test equipment so that once you have done the schematics you can actually RUN the complete circuit on the PC - in real time
Joe
Hi,

So I guess I will be sending you my MAX7219 PCB,s to run on Labcentre Proteus then :lol: :lol: :lol:
Might be a good exerciser.

Did you buy and try just the MAX7219 chip? I am not talking about unsoldering a chip from a board, A new one. !!
Keith

@Ralph Whilst still on topic. I do not mind if some of these posts are moved to the other thread. Up to you guys.
Hi Keith, I have both DIP and SO versions on various devices of various ages - such as some of these boards and plenty of the dot matrix display (the 8x8 units). I used both to test. I will have a batch of 10 arriving (complete 8 display units in a couple of weeks (the cheapest ones - or near enough) to test in longer strings / chains. It will be extremely interesting to look at the scope signals with, say, 5 devices chained. I only have a 2 channel scope, it is times like this a 4 channel would be better but it is perfectly adequate. It is definitely better to run your traces carefully and these boards a certainly not optimised !, and that is being kind. However, if a single easy 'fix' can be done - as in ringing the clk / gnd etc then great. Will see, it is good to dust of the scope. Thinking about it, I do have an 8 channel data analyser as well so can use that. We will see, but at least looking at the actual signals will tell us a lot. Anything learnt from that could, if necessary be implementing in a board layout if necessary. These boards have 'been around the mill' as they have been around so long and the net is not full of issues so it is easiest in the first place to simply test them with the right equipment and see where and what may be happening.
It is all good fun. I can then post the results here.
Oh, just to add.. ALL tests will be done on Arduino directly from the IDE and appropriate LIBS with both software and hardware SPI, not with AM as to use AM at this stage would add another unwanted variable. Only after Arduino tests will I move onto AM.
Joe
Joe. CISSP, MSc.

User avatar
jph
Posts: 2846
Joined: Fri Apr 10, 2020 12:50 pm
Location: Somewhere over the rainbow..

Re: Character Display possible issue.

#25 Post by jph »

I agree with Keith that, if necessary, some posts could be moved to another thread. However, I think this is relevant.

Many people buy small SMPS psu units, or use PC PSU units - or even, god forbid, 5V phone chargers etc. Don't for one minute think that plug in chargers (wall warts) are necessarily better - although some maybe superb. It all depends on the source and make and if it is a copy or not. The wall warts are also SMPU and can have exactly the deficiencies as the SMPS unit on the right.

I mentioned before about 'meanwell' SMPS (switched mode power supply) units which are industry standard. - please note - due to meanwell being a large and respected company and also having REAL legal clout ! - I have never seen a rip off or 'clone' or otherwise that uses the 'meanwell' label. So, if you buy one, you can be assured you are buying the genuine article. Meanwell has a genuine outlet on aliX, BUT ! you will almost certainly have a local distributer with similar prices as they sell all over the world.
Here is a quick image of two 12V units (50W each) both similar prices. The left is a genuine 'meanwell' unit - the right is a total knock off pile of crap.
The meanwell has ALL input mains filtering including proper common mode chokes, X and Y caps (genuine) MOVs and transient suppression, a PROPER certified transformer and fully over-rated mains rectifier and LV output rectifier and also genuine 105C low ESR caps. On the output, it has also, genuine - quality made low ESR 105 rated caps, inductors etc for proper output filtering. The Meanwell will give a damn good stable and noise free supply, the one on the right will be absolutely utterly crap as far as supply noise is concerned which will play havoc with any circuit you connect to (ie - 7219 displays - LCD modules - I2C units etc etc. The one on the right is only fit for the rubbish bin ! it is an utter piece of shit.
Connecting the RIGHT HAND PSU (if it was a 5V version) to something like Arduino and display units will result in an absolutely crap supply which as as noisy as hell. (and it could be LETHAL !)
Any questions please ask - hopefully the simple lack of of components in the right hand units offers some clue as to the - lack of - quality. The clearly seen areas with 'missing' components are ALL about filtering the input and output noise and due to that produce HUGE amounts of crap that goes into your supply line - and usually into others around it. Cheap computer PSUs are also as bad if not worse.
CONNECTING SOME CRAP LIKE THIS TO A TIMING CRITICAL CRITICAL CIRCUIT IS A TOTAL NO NO.
It hopefully - just shows what you may be buying even though - externally - they look similar. - and as said - can be LETHAL.
Joe.
smps.jpg
Joe. CISSP, MSc.

User avatar
Keith Baxter
Posts: 4674
Joined: Wed Dec 20, 2017 11:00 am
Location: Botswana

Re: Character Display possible issue.

#26 Post by Keith Baxter »

jph wrote: Wed Jan 05, 2022 8:51 am
Ralph wrote: Tue Jan 04, 2022 2:25 pm I haven't followed any of this, so I'm completely clueless :)
:lol: @Ralph
That doesn't entirely translate 100% :D
LOL @Ralph :lol: :lol:
its-a-trap-phoebe (1).gif
its-a-trap-phoebe (1).gif (173.96 KiB) Viewed 1389 times
Keith
AMD RYZEN 9 5950X CPU, Corsair H80I cooler, ASUS TUF GAMING B550-PLUS AMD Ryzen Mother Board,  32Gb ram Corsair Vengeance 3000Mh, MSI GTX960 4G graphics card 

User avatar
Ralph
Posts: 7878
Joined: Tue Oct 27, 2015 7:02 pm
Location: De Steeg
Contact:

Re: Character Display possible issue.

#27 Post by Ralph »

I had some 100uF caps from Würth Elektronik which I still had as a sample. Soldered one on each display, and now it works like a charm. Even had all 4 of them running on a one millisecond timer, works perfect.

Thank you all for the advice!
So if you have problems with these displays then it's most probably a hardware issue.
IMG_20220106_134300.jpg

tomlithgow
Posts: 60
Joined: Sun Jun 12, 2016 3:11 pm

Re: Character Display possible issue.

#28 Post by tomlithgow »

Just to be controversial...I have been away from flight simming and developing AM hardware instruments for almost a year, having packed everything away for moving house in March last year.

The first instrument(s) I developed when I started making AM hardware, in 2020 was a Nav/Com unit. I had four daisy-chained pairs of MAX7219 displays running off a single Arduino Mega back then. This was using v3. Having set this up now with v4 the second displays don't function. I have tried a different Arduino and different displays and no joy.

The only thing that has changed in this setup is the software so I challenge the claim by AM that it is not a software issue.

User avatar
Corjan
Posts: 2936
Joined: Thu Nov 19, 2015 9:04 am

Re: Character Display possible issue.

#29 Post by Corjan »

Hi,

I had the complete opposite experience, where I couldn't get it to function both in AM related code and in pure Arduino code.
These things are not that stable. But it seems using the latest AM BETA and with additional caps on the power line it works.

Corjan

User avatar
Ralph
Posts: 7878
Joined: Tue Oct 27, 2015 7:02 pm
Location: De Steeg
Contact:

Re: Character Display possible issue.

#30 Post by Ralph »

The caps made all the difference in our case, and for others as well. It's recommendable to have at least 10uF on each display.

Post Reply