Go Down

Topic: MAX7219 8x8 LED matrix FC-16 module useage suggestions (with MaxMatrix library) (Read 2334 times) previous topic - next topic

mcrobot

I spent some time looking for basic requirements when using this module.  Couldn't find anything.

Here's how I got a display in working order.  It needs some tweaks to work well.

Not sure where to post this kind of info.  Feel free to repost it or remove it.

Thanks.

Mark


Hope this helps those using this module.


8x8 LED max7219 fc-16 hardware modules


What I like about these modules is that they provide a display that

can be seen from a distance.   But there are a couple requirements

to get them working well.  I'd always use an external power supply.

There's 64 LED's in each matrix.  If they draw 10ma each, that's a

total of 640ma for only one matrix when every LED is on.  They need

a power supply for reliable, consistent operation.  It's not optional.


Just spent a couple hours sorting out hardware issues on these.

They are picky about ground connections.  And they need filter caps.

I will not spend any time to isolate every detail of their operation.


In any case I would recommend soldering an electrolytic filter cap

across Vcc and GND at the top of each module.  At least 1uF, or

larger.  I used what I had on hand.  It's a prototype.  Max7912

drivers generate switching currents when driving LED's.  Filter caps

help reduce voltage spikes that will interfere with control signals.

Random and intermittent operation results without them, depending on

how many LED's are being driven.


These two requirements are not optional for any hope of hardware

stability.  What follows is not as critical.


I soldered all connectors across a 10 matrix display.  Vcc and GND

were all soldered with separate leads to an external power source.

Each module has its own Vcc and GND lead to the power source.  These

are NOT wired in series like the original configuration.  Parallel.


Signal wires (3) must be connected in series from the bottom of one

module to the top of the next module.  This is standard configuration.

I soldered all of these connections.  DIN, CS, CLK.


Then, all the bottom Vcc connections are left open and all bottom

GND connectors are soldered to a single wire, in series, which is

then connected to an UNO GND pin.


Since making these mods, hardware issues are resolved.  There are

probably other ways to address hardware issues, but these mods work

well for me.


MaxMatrix code has to be edited when writing to more than nine

modules.  At least for the revision that I found online.  Everywhere

there is an '80' or '81' in the .h or .cpp file I changed to a

value of '88'.  It now writes to ten modules connected in series.

If you add more modules, keep increasing these numbers until it

writes correctly.  I did not go through all the code, so I can't

say how this works, exactly.  There's almost no comments in the

code, and I don't want to spend any more time on it.


I have not had any trouble working with my display since making these

mods.  I'm using a total of ten (10) FC-16 modules.


There's no substitute for a soldering iron.  And I might add a

resistor here and there in signal lines if any other hardware issues

crop up.  It's always a good idea to add current limiting resistors

on all signal pins/ports of your Arduino.  There's nothing quite like

stable hardware, and it's seldom mentioned.  (I see these issues quite

a bit watching youtube video.)  It makes coding that much easier.


Again, I really like these modules for a display.  They just need a

little help to get them working well.  It's hard to complain about

price, and there's a number of ways they can be configured for

display purposes -that you can see across the room-.  64 outputs for

each matrix.  In combinations, many more than that.  Kinda cool.


Then, there's SPI applications...  Later.

ieee488

I didn't read through your entire dissertation.
You can use the Parola library with the FC-16 modules.
https://github.com/MajicDesigns/MD_Parola

thedoc8

I spent some time looking for basic requirements when using this module.  Couldn't find anything.

Here's how I got a display in working order.  It needs some tweaks to work well.

Not sure where to post this kind of info.  Feel free to repost it or remove it.

Thanks.

Mark


Hope this helps those using this module.


8x8 LED max7219 fc-16 hardware modules


I was having all kinds of interment problems and made the same basic changes and bam no problems. Thanks for the post.

What I like about these modules is that they provide a display that

can be seen from a distance.   But there are a couple requirements

to get them working well.  I'd always use an external power supply.

There's 64 LED's in each matrix.  If they draw 10ma each, that's a

total of 640ma for only one matrix when every LED is on.  They need

a power supply for reliable, consistent operation.  It's not optional.


Just spent a couple hours sorting out hardware issues on these.

They are picky about ground connections.  And they need filter caps.

I will not spend any time to isolate every detail of their operation.


In any case I would recommend soldering an electrolytic filter cap

across Vcc and GND at the top of each module.  At least 1uF, or

larger.  I used what I had on hand.  It's a prototype.  Max7912

drivers generate switching currents when driving LED's.  Filter caps

help reduce voltage spikes that will interfere with control signals.

Random and intermittent operation results without them, depending on

how many LED's are being driven.


These two requirements are not optional for any hope of hardware

stability.  What follows is not as critical.


I soldered all connectors across a 10 matrix display.  Vcc and GND

were all soldered with separate leads to an external power source.

Each module has its own Vcc and GND lead to the power source.  These

are NOT wired in series like the original configuration.  Parallel.


Signal wires (3) must be connected in series from the bottom of one

module to the top of the next module.  This is standard configuration.

I soldered all of these connections.  DIN, CS, CLK.


Then, all the bottom Vcc connections are left open and all bottom

GND connectors are soldered to a single wire, in series, which is

then connected to an UNO GND pin.


Since making these mods, hardware issues are resolved.  There are

probably other ways to address hardware issues, but these mods work

well for me.


MaxMatrix code has to be edited when writing to more than nine

modules.  At least for the revision that I found online.  Everywhere

there is an '80' or '81' in the .h or .cpp file I changed to a

value of '88'.  It now writes to ten modules connected in series.

If you add more modules, keep increasing these numbers until it

writes correctly.  I did not go through all the code, so I can't

say how this works, exactly.  There's almost no comments in the

code, and I don't want to spend any more time on it.


I have not had any trouble working with my display since making these

mods.  I'm using a total of ten (10) FC-16 modules.


There's no substitute for a soldering iron.  And I might add a

resistor here and there in signal lines if any other hardware issues

crop up.  It's always a good idea to add current limiting resistors

on all signal pins/ports of your Arduino.  There's nothing quite like

stable hardware, and it's seldom mentioned.  (I see these issues quite

a bit watching youtube video.)  It makes coding that much easier.


Again, I really like these modules for a display.  They just need a

little help to get them working well.  It's hard to complain about

price, and there's a number of ways they can be configured for

display purposes -that you can see across the room-.  64 outputs for

each matrix.  In combinations, many more than that.  Kinda cool.


Then, there's SPI applications...  Later.

Paul__B

I didn't read through your entire dissertation.
Mostly as it was typed on a mobile phone or some equally awful device, making it so painful to read!  :smiley-roll:  :smiley-roll:  :smiley-roll:

Go Up