Mega and 2 FC-16 Modules

@zander 

Maybe, but since he says he's got the first display up and running, he knows what he's getting.

I really don't feel confident about what he's after either.

Posted by: @zander

@will I give up

Im sorry Ron, I don't mean to frustrate you or offend you. I think we'll have to wait until the OP comes back and gives us more details about what he's really looking for.

@will He got it working because he downloaded it, he has written no code that I am aware of.

He has even bigger problems, go back and read his first few posts. He wants to make the messages on his PC screen (2 different message streams, maybe even 2 different PC's) appear on two different 8x8 matrix LED's (maybe more than 1 as in the sample of 4 so 8x32)

At some point he said the 'developer' would provide the data on the D1 pin. I doubt 99.99999% that the developer did not mean that. Unfortunately we have a case of DK here. At the moment he needs to get the data to be displayed by his Mega across an air gap. Keeping in mind he doesn't know the purpose of a buffer I suggest this is an extreme challenge. Rule 1.

@will Sorry will, I was getting frustrated with your insistence this can be done on a single display. It can be done by carefully creating the data buffer from 2 separate sources, but I rule that out based on his newbieness. As you say util he posts a requirements statement it's hard to tell.

@zander 

I see. Is this a restart of another thread from the past ? If so, I missed (or forgot about) it because I'm just basing this on the contents of this post alone, so I'm waaaaay out of context.

Here is where I started.

https://lastminuteengineers.com/max7219-dot-matrix-arduino-tutorial/

I have two FC-16 modules which will not be connected together. Two separate displays.

Thanks everyone.

@will I did start awhile back trying to use OLED devices and backed off on them as they were too small for what I wanted to do.   Found out the 8x8 matrix with the MAX72xx was simpler for me to understand.

@will YES, his new member post contained some relevant info, see 

https://forum.dronebotworkshop.com/postid/23988/

Posted by: @alan-l

I have two FC-16 modules which will not be connected together. Two separate displays.

Can you tell us what kind of data will be displayed ? 4 bytes of numbers, icons, letters, all three  ?

Do you understand that you have only 1 SPI bus on the MEGA ?

Sorry to get you guys involved. I will figure this out in time. I am retired so do have plenty of time.

Thanks again for your guidance.

Regards - Alan

Posted by: @zander

@will YES, his new member post contained some relevant info, see 

https://forum.dronebotworkshop.com/postid/23988/

Thanks Ron, i'll have to jump in the Way Back machine and reread that thread.

Alas, now it comes back to me.

However, after rereading the intro, and due to the fact that he still seems happy with the 8x32 dot matrix display (leading me to conclude that both display will be adequate for his needs), I'm even more confident that the second display can be daisy chained off the first one with a suitably long 5-wire cable.

Otherwise, it'll be an awful task to whip off a second SPI interface to drive a second display.

@alan-l Get TWO of the MAX72xx modules, the second one will have 4 of it's pins connected to the same 4 pins on the first module. The only one that is different is the DIN pin. Choose another similar pin (Digital? 9?) then copy the code and change the DEFINE for DIN from pin 11 to maybe 9?

Now when you copy the code you will need to create duplicates of some things like buffers. I don't know what else since I don't have the code, but if the code is in a separate module, then you can probably copy it in it's entirety. This part is basic simple programming. 

Now you just have to figure out how to get the data into the arduino, your comment about the developer giving it to you on a pin on the arduino is unbelievable for a couple of reasons. First who is paying him for an effort probably costing at least $60,000, second to 'bring that data out to a pin on the Mega means ????, is he using a cable between the PC and the Mega, or what exactly. You need well thought out requirements and they then need to be analyzed for technical possibility followed by economic feasibility. You are trying to start at step 5 without ever doing the first 4 steps. Won't work.

Sorry if I seem harsh, but as a very senior adviser to IBM management I had to do this with MS and PHd level people all the time. Every single one of them was off by 2 years on their estimates. 

You can get there, but start at the beginning. Have a look at the 3rd kind of screen, a TFT 320 x 240 pixels, that can be up to 40 characters wide.

Posted by: @alan-l

Sorry to get you guys involved. I will figure this out in time. I am retired so do have plenty of time.

Don't be sorry, trying to help people out is why both Ron and I are here; either to help other people who need help or get it when we need it.

You just need to realize that YOU have all the information and we're trying to advise you when sometimes we don't know what you're doing. That makes it hard for us to offer constructive advice 🙂

Have you received any word from the developer about how or when he'll be making the changes required to provide you with the extra data required to drive the display ?

@alan-l Why not start with a built in sample sketch for SPI bus to get to know how to use it, then move on to 2 SPI pins.

@will Are you sure? It 's a MEGA