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Forum Index : Microcontroller and PC projects : Driving two LCD’s from an E100...
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9610 |
Hi all.  I have a need to run TWO screens from one E100. They both need to show exactly the same information. Probably 5", but maybe 7". Does anyone have any bright ideas as to how I would do this? Buffers of some kind I guess..... Smoke makes things work. When the smoke gets out, it stops! |
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| PeterB Guru  Joined: 05/02/2015 Location: AustraliaPosts: 655 |
G'Day Grogster You do come up with some lulus. If data is only flowing E100 to display then you would probably not need buffering but if you want data to flow display to E100 e.g. touch, then heaven help you  Pete |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9610 |
lulus? Please define lulus.  No, don't care about touch, only display. Mimic panel, one facing down a hallway, the other one facing the other way down the same hallway. Do you think I could just parallel them up? I figured there might be some buffering required to isolate each display from each other and the MM driving them. Perhaps not. Smoke makes things work. When the smoke gets out, it stops! |
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| PeterB Guru Joined: 05/02/2015 Location: AustraliaPosts: 655 |
Sorry, I forget there are young people out there. A lulu is a difficult / strange / funny / odd problem. It probably date back to the 60s. Long before you were born and I have no idea what the modern equivalent is but it probably uses many Fs. The E100 outputs are capable of quite high current and should be able to drive reasonable length cables. Suck it and see. Do I have to explain that one? Good luck. Peter |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9610 |
Re: 60's - not that long before I was born - 1974.  [Quote]Suck it and see. Do I have to explain that one?[/Quote] LOL! No, I know that one! Thanks. I might then see if I can parallel up a couple of displays for output only, and see if they work. Still very interested in any other members thoughts on this idea. Smoke makes things work. When the smoke gets out, it stops! |
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TassyJim Guru Joined: 07/08/2011 Location: AustraliaPosts: 6283 |
Make sure you don't use the RD pin. That will stop you doing blitting and transparent text but the displays should be write only so it 'should' work with simple parallel connections. You will also need a hefty power supply. Jim VK7JH MMedit |
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MicroBlocks Guru Joined: 12/05/2012 Location: ThailandPosts: 2209 |
Connecting the RD pin from only one of the screens should work, right....? Microblocks. Build with logic. |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3378 |
Well before the 60s. It was an expression my mother used, and I was born in 1946. Probably similar in timeframe to "doozie"--as in: "that's a doozie". One of my cousins was nicknamed Doozie, and she was born in the early 30s. I don't even remember her given name. PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| Paul_L Guru Joined: 03/03/2016 Location: United StatesPosts: 769 |
Way back in the 1920s lulu came into use to describe a wacky person, usually a girl. |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9610 |
[Quote=Jim]You will also need a hefty power supply.[/Quote] Agreed. The initial plan at this stage is to use a totally separate regulated PSU circuit just for the two LCD screens. That takes the load off the E100 completely. It will only be logic signals to the LCD's. Everything being fed from one master PSU capable of 3A or so. 12v Meanwell UPS power supplies of that rating are easy to come by and quite cheap. [Quote=MB]Connecting the RD pin from only one of the screens should work, right?[/Quote] I expect so. As I only want display and no touch or any transparent text/blit etc, I was not planning to connect RD either. I hope to hook a couple of 5" LCD's up this weekend to an E100 and run a test. I will get one going first, then add the 2nd one and see what happens. I will keep the forum updated. I've heard of lulu being used as short for Louise. Smoke makes things work. When the smoke gets out, it stops! |
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OA47 Guru Joined: 11/04/2012 Location: AustraliaPosts: 986 |
Thinking outside the box Why not use a slave E100?OA47 |
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| TassyJim Guru Joined: 07/08/2011 Location: AustraliaPosts: 6283 |
Make sure you have the video recorder running. We want to see the smoke in full colour. Jim VK7JH MMedit |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9610 |
@ OA47: Yes, I am also thinking about that, but I will see what happens with the two LCD idea first. @ Jim: Awwwwwww, c'mon man! You'll jinx it with comments like that!  If it does not work, I can blame you then. That works for me.  Smoke makes things work. When the smoke gets out, it stops! |
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| PeterB Guru Joined: 05/02/2015 Location: AustraliaPosts: 655 |
G'Day all lizby, "that's a doozie" is from the Duesenberg car which was considered to be the best by Americans. It was so good it went belly up in 1937 probably in honour of my birth. It did however have the first car computer. A mechanical thing that told you when to change the oil etc. Jim, how could you? Nothing can possibly go wrong....click ... ong ......click.... ong .... click Peter |
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CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 2170 |
Sorry grogs, late to the party on this (work got in the way). if the information is the same each time I would simply common all the connections, so long as you don't read anything you'll be fine For seperate control (and in your place I would probably keep that option open), I tried multiplexing the CS pin but in the end it was easily solved with software and having two CS pins under program control and flipping them as required. This does waste the CS pin when you define the display but it meant I could select both CS simultaneously for the initialisation routine and then I just flipped the pin for whichever display I wanted to write. A total software solution, no buffers/multiplexers or anything I did this with some smaller 2.4" displays here in that link, you can see the two initialsations are run seperately here is my code from that demo about - it might give you some ideas ' OPTION LCDPANEL ILI9341, orientation, D/C pin, reset pin [,CS pin] ' OPTION LCDPANEL ILI9341,RL,15,19,21 SetPin 23,dout: Pin(23)=1 SetPin 24,dout: Pin(24)=1 Pin(23)=0:GUI reset lcdpanel:Pin(23)=1) Pin(24)=0:GUI reset lcdpanel:Pin(24)=1) Colour RGB(white), RGB(BLACK) ' Set the default colours Font 1,2 ' Set the default font Do For n=23 To 24 Pin(n)=0 Box 0, 0, MM.HRes-1, MM.VRes/2, 3, RGB(RED), RGB(Rnd*128,Rnd*128,Rnd*128) Text MM.HRes/2, MM.VRes/4, Time$, "CM" , 1, 4, RGB(CYAN), DBlue 'Text MM.HRes/2, MM.VRes*3/4, "Disp"+Str$(n-22)+" "+Date$, "CM" Text Rnd*320, Rnd*240, "Disp"+Str$(n-22)+" "+Date$ Circle Rnd*320,Rnd*240,Rnd*100 Box Rnd*320,Rnd*240,Rnd*320,Rnd*240,3, RGB(Rnd*128,Rnd*128,Rnd*128) Pin(n)=1 Next 'Pause 100 Loop earlier vid here showing the very simple setup with no hardware more than the uM and the displays my 2p |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9610 |
Great, thanks Captain. The vids are encouraging, even though you used SPI ones and I will be using parallel SSD1963 ones, but the concept remains the same, so should work. Did you find that you needed to have separate CS lines and to initialize the LCD's separately, or were you able to initialize both LCD's simultaneously by just paralleling them up? I will keep open the idea of have a separate software CS line for each display - just to be safe. Smoke makes things work. When the smoke gets out, it stops! |
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| CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 2170 |
Yes, I completely ignored the CS pin as defined when setting up the panel - it is a loss but a small price at just one pin I can't use in return for independent control. I think if you simply wanted duplicate displays, you could possibly just parallel everything. Any problems would be around both displays trying to write something back at the same time - if you ensure that doesn't happen then I reckon you are good to go. see the code above, third paragraph, first two lines show me toggling the individual CS line with two GUI RESETs. You can see the effect of that in the vid - both displays go white together as the power comes up then in turn they clear to black - that is the GUI RESET right there. I developed this coz I wanted a wide display, behind smoked perspex - looks ok... could be a bit brighter but does the job and I am just careful that what I write to the screen the middle bit (where I trimmed the edge of the board to minimize the gap) isn't obvious. hth EDIT: Only just noticed, the OPTION LCDPANEL... the CS pin is optional (doh!) you don't even lose the pin - if it is the same on your panel then happy days. |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9610 |
So, are you saying just parallel up the CS pins too? Then MMBASIC will CS both displays at the same time, and initialize. I am hopeful that should work. I hope to hook a couple of displays up tomorrow. I will get the video camera ready for the benefit of Jim. EDIT: No. CS on the parallel LCD's is always at ground, so the LCD is always selected. I will go on that assumption. ....and assumptions being the mother of all..........yes, well, we all know the rest of that line. Smoke makes things work. When the smoke gets out, it stops! |
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| CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 2170 |
yep. I'd defo give it a whirl... so long as the displays don't write back to your MM. Faint heart never won the fair maiden and all that... They are both getting the same stimuli, barring signal degradation from loading (very unlikely these days - was a nightmare back in the 80's... first thing out of a Z80s data bus was a '245 ) I think it will work. Looking forward to the vid |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9610 |
"I never understood the necessity to become irrational in order to prove that you care. Or indeed, the necessity to prove it at all." - Avon from Blake's 7. Smoke makes things work. When the smoke gets out, it stops! |
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