Electronics > Projects, Designs, and Technical Stuff
Critique my first PCB
bitseeker:
--- Quote from: carl0s on July 15, 2018, 06:29:04 pm ---
--- Quote from: lukewren on July 15, 2018, 05:44:49 pm ---I realise you now have your boards back (and they work! awesome! :-+ ) so it's probably a bit too late, but... why do you have thermal relief on your stitching vias?
--- End quote ---
What's that then?? :)
Is that something to do with the vias looking like a cross-hair? (I have no idea why that is.. Altium just did that).
--- End quote ---
Nice job with that board, Carl. It was cool seeing it improve as the thread progressed.
I, too, was wondering about the thermal relief on the vias. Yes, it's those crosshair-looking structures. They reduce the rate at which heat flows from the pad to the ground plane so that it's easier to heat the pad for soldering. Normally, you'd do that where you have to solder through-hole parts, otherwise a soldering iron might struggle. Since these are vias, they're not needed.
I haven't used Altium, but there must be an option to turn off the thermal relief or perhaps choose a different part for vias vs. plated through holes for leads. Of course, it won't affect anything the way it is since those are simply vias. It just looks odd. Something to figure out for the next PCB.
carl0s:
--- Quote from: bitseeker on July 16, 2018, 06:33:10 am ---
--- Quote from: carl0s on July 15, 2018, 06:29:04 pm ---
--- Quote from: lukewren on July 15, 2018, 05:44:49 pm ---I realise you now have your boards back (and they work! awesome! :-+ ) so it's probably a bit too late, but... why do you have thermal relief on your stitching vias?
--- End quote ---
What's that then?? :)
Is that something to do with the vias looking like a cross-hair? (I have no idea why that is.. Altium just did that).
--- End quote ---
Nice job with that board, Carlos. It was cool seeing it improve as the thread progressed.
I, too, was wondering about the thermal relief on the vias. Yes, it's those crosshair-looking structures. They reduce the rate at which heat flows from the pad to the ground plane so that it's easier to heat the pad for soldering. Normally, you'd do that where you have to solder through-hole parts, otherwise a soldering iron might struggle. Since these are vias, they're not needed.
I haven't used Altium, but there must be an option to turn off the thermal relief or perhaps choose a different part for vias vs. plated through holes for leads. Of course, it won't affect anything the way it is since those are simply vias. It just looks odd. Something to figure out for the next PCB.
--- End quote ---
Thanks! Yes I googled thermal relief vias and found some pictures in the end. I'll watch out for it next time.
carl0s:
--- Quote from: james_s on July 16, 2018, 12:55:23 am ---That looks really good, it's always very exciting when a complex display like that actually works. That would make an interesting analog style desk clock or weather station, I've always been fond of analog dials.
--- End quote ---
It sure is an interesting screen. It's quite bright (650 nits), and doesn't have a touch screen. Meant for industrial/scientific. Will do nicely for some kind of automotive gauge I think. It is part of my foray into MIPI DSI screens on microcontrollers. There aren't many MCUs that do MIPI DSI, but the STM32L4+ does - it does up to 2 lane MIPI DSI. This screen only needs 1 lane. I think the interesting thing is (although I know nothing about non-MIPI screens...) that the command set is somewhat standardised. So it should be pretty easy to get different screens going. Famous last words..
My next project, is to try to get this much bigger round TFT to work. This is a proper ~3.4" TFT. You can see it's a lot bigger than the octagonal one that I have had success with - that one is also sold as 3.34", but it's really about 2.4". It was possibly cut from a 3.34" square once upon a time though. This bigger one requires 3 MIPI lanes, and no MCU supports that, so part of the project will involve getting the SSD2828 RGB to MIPI bridge chip working. That's the QFN68 chip that you can see on the proto-board there. This big one is gram-less i.e. has no internal graphics memory/framebuffer, and I don't know enough about these things yet to know how much harder that will make things, but it'll be interesting having a go! The dev board I have, and the ST discovery board, all have decent amounts of SDRAM or PSRAM etc which I think can be used as the framebuffer, and they both have LTDC (LCD TFT Display Controller) which handles a lot of the work for you as far as I know.
Oh yeah that's what I meant to say.. this big round one is 800*800px !! It really does look like a beauty, but, the brightness according to the datasheet is only 350 nits, and this has sort of put it on the back burner for me, also the complexity of my first project of course.. I have started with the simpler 1-lane MIPI.
dlo:
Nice work Carl! I'm trying to do something similar with a smaller 2.1" DSI LCD using the ST7796H2 controller. Can you share what files you edited to make yours work? Thanks!
luiHS:
Hi carl0s.
I will use the same octagonal screen, for now the only thing I know is that it uses the ST7796SI controller, I have no experience with MIPI DSI screens.
From what I understand, it is necessary to send some commands to initialize it. In my case I will use an STM32F769 microcontroller, because it has hardware JPEG decoding, I will test it with a Discovery evaluation board. I have also made my adapter board (pictures attached), to connect it to the Discovery, this includes a voltage booster (18v) for the backlight.
Could you share the modifications you made to the source, to initialize this screen? As you indicated, you removed all the initialization commands from the kit, and with that it started working, but you added a command to make it work perfectly.
Regards
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version