[0:00] look at this thing of beauty I do love a
[0:02] nice bit of silk screen so my ESP 32 ZX
[0:05] Spectrum project is fully funded on
[0:07] crowd Supply and I’ve started ordering
[0:09] components so I’ve done a massive order
[0:11] for displays so each layer of this has
[0:14] 10 displays and there’s five layers so
[0:16] that’s 50 displays and I got another
[0:18] three boxes so what I wanted to do was
[0:21] make sure these displays actually work
[0:23] with the current pcbs and they do really
[0:26] nicely so it’s now time to do another
[0:27] bulk order of pcbs as I’ll be using PCB
[0:31] way for the um pcbs and assembly they’ve
[0:33] worked really well can recommend them
[0:35] check out the link in the description
[0:37] they’re on great job on all the
[0:38] prototypes but before doing this B order
[0:41] I wanted to make a couple of tweaks one
[0:43] of the things that has occurred to me is
[0:45] that we have this lovely full color silk
[0:46] screen on the front of the board but
[0:49] pretty much nothing on the back this
[0:51] feels like a bit of a waste of real
[0:53] estate so I’ve designed some nice
[0:54] digital information to fill this space
[0:57] it is surprisingly easy to get quite
[0:59] detailed so screen into key CAD so you
[1:01] can see I’ve got quite a nice one for my
[1:04] speaker here which shows you where to
[1:06] place the speaker now you can of course
[1:08] use the uh Graphics tools built into key
[1:10] CAD we have lines arcs squares circles
[1:13] polygons and text but it’s not the
[1:16] easiest thing to use so I much rather
[1:18] use a um Graphics design tool so as I
[1:21] say this is reasonably straightforward
[1:23] but there are a few wrinkles to be aware
[1:25] of so I want to go through my process
[1:27] just to document it mostly for myself to
[1:29] be honest so I’m using my design tool
[1:31] it’s called Affinity designer now
[1:33] there’s a few interesting things so when
[1:35] we do a new document now I know that my
[1:38] um my ESB 32 board is 233 mm x 144 now
[1:44] most design software will have something
[1:46] called a DPI so that’s dots per inch so
[1:48] what we can do is we can use this dots
[1:50] per inch and we can use the size that we
[1:52] want to work out how many pixels to end
[1:54] up with so if we do um 233 millimet in
[1:59] inches
[2:01] and you can see that’s 9.17 in so if we
[2:05] do
[2:07] 9.17 time 300 you’ll see that it will
[2:10] end up with a document of around 2,700
[2:13] pixels so obviously my design software
[2:15] is paid for and quite expensive but they
[2:18] are some really nice open source
[2:19] software uh one of them is photopia now
[2:22] you can see in the setup for this it
[2:24] also lets us specify millimeters so we
[2:26] could do the same thing so 2 3 3 by 144
[2:32] now you see here it’s only using 72 DPI
[2:35] now that’s pretty good for displaying
[2:37] things on the screen and it’s probably
[2:39] okay for silk screen to be honest but
[2:41] you can just bump this up to 300 dots
[2:43] per inch and you can see it’s adjusted
[2:45] our width and height so we’ll put those
[2:47] back to what we want so another popular
[2:50] tool is inkscape so in here you create a
[2:52] new document and then you go file
[2:55] document properties and here you can
[2:57] specify the size of millimeters as well
[2:59] so we can do
[3:01] 233 by
[3:03] 1
[3:06] 144 and then when we export we’ll set
[3:09] the dots per inch for this or you can go
[3:11] over
[3:12] here and we can set the DPI here I’m
[3:16] going to stick with my nice design tool
[3:18] so what I’ve got here i’ got a nice bit
[3:20] of text and some description I’ve done
[3:22] all the gpio pins so it’ll be very easy
[3:24] as a quick reference to see what’s going
[3:25] on there’s a QR code so we can jump
[3:28] straight to the a speed to Rainbow site
[3:30] and done a quick sort of sketch of the
[3:33] board and all of the uh connectors so
[3:35] the speaker headphone expansion Port
[3:38] quick connectors
[3:39] USBC um another quick connector the SD
[3:42] card just so you can flip the board over
[3:44] and have a quick reference to see what
[3:46] um what the board actually does so I’ve
[3:48] exported this to a PNG and we’ll jump
[3:50] into key Cad and load it up so over in
[3:53] key CAD what we do is we click on the
[3:56] image converter so this converts bitmat
[3:58] images to schematic symbols or PCB
[4:00] Footprints so we click on that and it
[4:03] opens up now we can load in our source
[4:05] image so if I load in my silk screen
[4:08] image then you can see it’s been pulled
[4:10] in and it looks pretty good now what’s
[4:13] interesting is obviously in key CAD silk
[4:16] screen can only have black or white so
[4:18] it can’t do Shades of Gray now if we
[4:21] slide this slider you can see a slightly
[4:23] interesting effect you can see that our
[4:26] lines in our text get thinner and
[4:28] thicker depending on where we put this
[4:30] black and white threshold now we don’t
[4:33] really want that to happen ideally I
[4:35] want something wizzywig so what’s going
[4:37] on well let’s have a look at the image
[4:39] so here’s my silk screen that I’ve
[4:42] exported now what you can see if we zoom
[4:46] in really closely you can see that there
[4:48] are actually Shades of Gray in this
[4:50] image so what’s happening is my Graphics
[4:52] tool it’s using anti-aliasing to make
[4:55] this display nicely now the problem with
[4:57] that is it means we don’t have exactly
[4:59] what we see on the screen because you
[5:00] see here as a line it’s done some
[5:02] anti-alias in because this isn’t exactly
[5:04] on the pixel boundary so what I can do
[5:07] in my tool and other tools will be able
[5:09] to do this is I can select everything
[5:12] and then I can choose not to anti-alias
[5:14] so I can force off which is what I’ve
[5:16] done here now if I export the image now
[5:19] and we take a look at it so let’s open
[5:22] up this version which has the
[5:24] anti-aliasing switched off and then we
[5:27] zoom in and you can see that all we have
[5:30] are black or white pixels now if we go
[5:33] back to key Cad and if we replace the
[5:37] image I loaded with the version without
[5:40] aliasing so back silt screen no anti-
[5:43] Alias then you can see now this slider
[5:46] has no effect so we’re getting exactly
[5:49] what we see in our Graphics tool on the
[5:51] screen here now you can see up here that
[5:54] the dots per inch has been pulled in so
[5:56] it knows it’s 300 dots per inch and
[5:59] that’s how it works out what the size
[6:00] should be now you can actually modify
[6:03] all of this so you can go and change the
[6:04] DPI this is really handy if you’ve
[6:07] downloaded an image of the internet
[6:08] that’s not 300 DPI or it’s a different
[6:11] width and height and you want to adjust
[6:13] it so you can modify all of this stuff
[6:15] but I’ll leave mine in millimeters and
[6:18] um we’ve got our nice image so what we
[6:20] do now is we just do export to clipboard
[6:24] you can export to file and create a
[6:25] footprint but I find it faster just to
[6:28] export to clipboard now if we go to key
[6:30] Cad and we open up our PCB so here’s our
[6:34] PCB display we can just paste this in I
[6:38] need to flip it to put it on the back of
[6:40] the silt screen and then we place
[6:43] it where we want it so I want it around
[6:45] about here and then the only thing you
[6:48] have to remember to do is if you look
[6:50] closely here there’s this um reference
[6:53] for the silt screen so we double click
[6:55] on that and we make it not visible
[6:58] otherwise it will show up on our design
[7:01] so that’s now got our silt screen in and
[7:03] I think the best way to preview this is
[7:05] normally to go into a 3D viewer so if we
[7:08] open up the 3D
[7:17] viewer and we just position it so it’s
[7:19] in the right place come on key CAD
[7:21] behave you’re making me look
[7:28] silly so there we have our front and if
[7:31] we flip over we now have the nice back
[7:34] of our silk screen so that’s looking
[7:37] pretty good so this is all ready to
[7:40] actually um send off to PCB way so I
[7:43] need to order around 300 boards so
[7:46] that’s why I really wanted to make sure
[7:48] the display was going to work because I
[7:50] didn’t want 300 displays and 300 boards
[7:53] that didn’t work but I think we’re
[7:54] pretty good to go now so uh yeah very
[7:57] exciting on the ESB 32 rainbow front if
[8:01] you haven’t ordered it already why not
[8:02] go over to crowd Supply and place an
[8:04] order uh every little helps um there
[8:07] should be a great Fed so thanks for
[8:09] watching and I hope that was useful