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Forum Index : Microcontroller and PC projects : stm32f429 Discovery on VGA Monitor
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darthmite Senior Member  Joined: 20/11/2011 Location: FrancePosts: 240 |
Hi all ;) I just get some from the new stm32f429 Discovery board from ST. First thing i have do was to de-solder the LCD from one of the board and use the 18bits colors , vsync and hsync to try to get a picture on my VGA monitor. For this i made me a little R-2R Video DAC. After some attempt it finally work :) Now i can use the board for a 640 x 480 pixels with 262k colors. They is 8Mb SDRAM on-board , so we have allot for user stuff ... It's so fast that i will like to see a port of the MMBasic on this board ;) I just have now to fix one issue , i cant get a uniform color , i don't know if it is how the stm32 read the sdram or if i made a mistake somewhere in the setup for the video output. I have made a thread here for those who have the board want try it: stm32f429 vga Cheers. Darth. Theory is when we know everything but nothing work ... Practice is when everything work but no one know why ;) |
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vegipete Guru  Joined: 29/01/2013 Location: CanadaPosts: 1110 |
Nice, thanks for the alert about the stm32f429 Discovery. Cool looking unit, especially if the price settles to the MSRP of $24US. I've been playing off and on with my stm32f4 Discovery boards and thought porting MMBasic with video generation would be quite useful. Trouble is, I've got too many projects, too little time... and now you've gone and added another toy to drool over. ;-) Visit Vegipete's *Mite Library for cool programs. |
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| darthmite Senior Member Joined: 20/11/2011 Location: FrancePosts: 240 |
I just resolved the non uniform colors i have today. We just have to full erase the SDRAM after the memory test and the picture is now perfect !! The MMBasic on a 640 x 480 pixels with 18bits colors is a must have. And that for $24 :) But i work too much to get time to try a port on this stm32 beast ;) Somewhere i have see that we can use 800 x 600 pixel on this chip. But the datasheet say 640 x 480 ... hmmm ... bigger = better :) I will look at this soon ... Cheers. Theory is when we know everything but nothing work ... Practice is when everything work but no one know why ;) |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 3805 |
Cool board, pity about the restrictive licence. John |
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kiiid Guru Joined: 11/05/2013 Location: United KingdomPosts: 671 |
See this. It is coming out sometime next month with 800x600 resolution and a port of MMBasic 
http://rittle.org -------------- |
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| darthmite Senior Member Joined: 20/11/2011 Location: FrancePosts: 240 |
The STM32F427 don't manage SDRAM , DMA2D and LTDC :) But if the port of MMBasic is ok , why not directly use the STM32F429 from the new cheap ST Board ??? Theory is when we know everything but nothing work ... Practice is when everything work but no one know why ;) |
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| kiiid Guru Joined: 11/05/2013 Location: United KingdomPosts: 671 |
Yes, there won't be any SDRAM on board and the video is generated in a way somewhat similar to the Maximite's (although not exactly the same way). STM32F429 is not available on the market yet, only kits for it, but the difference from user's point of view won't be great anyway... http://rittle.org -------------- |
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| camguy Newbie  Joined: 12/10/2013 Location: FrancePosts: 5 |
Hi, STM32F429 boards are just reaching distris now. For those looking to use external SDRAM and DMA2D, there is an EvoPrimer STM32F429 board with demonstrations of use with graphics. No video examples though. There's a video of the demonstration on youtube... http://youtu.be/TJWeVvicvZk |
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| darthmite Senior Member Joined: 20/11/2011 Location: FrancePosts: 240 |
Hello :) You don't need extra external SDRAM. Everything is on the STM32F429 Discovery board. If you want try my VGA tips , just refer to the post i made on ST Forum. For $20 to $30 the board fitted with LCD + SDRAM we cant want more :) Ops ... yes , i forget VGA ;) I actually work on my board and wait a PCB i made to direct fit on the Disco board that contain 8M x 16Bits SDRAM + 512k x 16bits fast SRAM and the R-2R DAC + VGA Connector. I Added RAM because i have some here and don't want made a PCB just with a little R-2R DAC with his VGA connector. It will be fun the day i get the material for testing :) Here is the Schematic if someone want take a look : 2013-10-15_191945_stm429_top_expansion.pdf Cheers. Theory is when we know everything but nothing work ... Practice is when everything work but no one know why ;) |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 3805 |
Well, I'd want a board without the stupid licence as that makes it fit for very little. John |
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| kiiid Guru Joined: 11/05/2013 Location: United KingdomPosts: 671 |
Boards yes, but not chips. Since they are pin-compatible there won't be any problem to upgrade the design in future, but for now 427 is a more reliable choice. http://rittle.org -------------- |
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| darthmite Senior Member Joined: 20/11/2011 Location: FrancePosts: 240 |
I do it too and here with intensive maths the VGA signal become corrupted because of the DMA that can no more stay in correct cycle. One of my test is here : stm32f407 VGA test Look at 2min24 in the video when i start with 3D cube. This problem is resolved with the new DMA2D and LTDC 
The day you try the stm429 you no more look at the 407 or 427 .. he he I just read the licence , so long you don't sell the dev board it's not a problem , i sell nothing then it's ... not a problem .. Cheers. Theory is when we know everything but nothing work ... Practice is when everything work but no one know why ;) |
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| darthmite Senior Member Joined: 20/11/2011 Location: FrancePosts: 240 |
Hi
I just made a short video from the stm429 Discovery board VGA output. STM32F429 Discovery VGA test The next will be when i get the PCB + component for build my little expansion board
Enjoy. Theory is when we know everything but nothing work ... Practice is when everything work but no one know why ;) |
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| darthmite Senior Member Joined: 20/11/2011 Location: FrancePosts: 240 |
Happy new year
As promised , here a video (not so good quality) from the actual expansion board and latest informations. Expansion board Demos I clean the code and post it soon. Cheers. Theory is when we know everything but nothing work ... Practice is when everything work but no one know why ;) |
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| darthmite Senior Member Joined: 20/11/2011 Location: FrancePosts: 240 |
Done , Code cleaned (as most i have can) You can get it here : st429 Expansion library And as usual , everything is ... freeware ... Now , we just need to add MM Basic  (Darth see Geoff Hide ...)
Cya. Theory is when we know everything but nothing work ... Practice is when everything work but no one know why ;) |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 3805 |
Interesting - but aren't you using a speed (192MHz) higher than is specified for the CPU? I couldn't find the board on seeedstudio :( John |
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9308 |
Very impressive.  Smoke makes things work. When the smoke gets out, it stops! |
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| darthmite Senior Member Joined: 20/11/2011 Location: FrancePosts: 240 |
For the speed you don't have allot of choice if you want use the USB port in the future. Or you low the freq. at 168Mhz or you up it at 192
The 3 boards i made work all great with 192Mhz and 'my' normal test phase is minimum 48h of running a demo or benchmark. I have remade the SDRAM library for use it with 2 Memory chip , i then just adapt the SDRAM timing parameters. The delay routines and VGA Drivers are for 192Mhz too. If i go down to 180Mhz now , i will have to adapt all VGA parameters , timer routines etc. About SeedStudio i will ask them this evening after the work or if you want build the board you can send them the Gerber file attached to this thread. OpenPCB use the same file format for Gerber (but they are slow) 2014-01-09_054214_st429_top_exp_v2_5pcs_10by10.zip Cheers. Theory is when we know everything but nothing work ... Practice is when everything work but no one know why ;) |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 3805 |
The manufacturer run their boards at 168MHz for USB. They're not spec'ed to 192MHz and from past experience the grief caused by problems in the customer base due to overclocking is HUGE. I strongly suggest that for any published work you stick to the specs. John |
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| darthmite Senior Member Joined: 20/11/2011 Location: FrancePosts: 240 |
I know for the Specs , the normal speed is 180Mhz for st429 , but , to be clear , i run at 192Mhz (sometimes 5 or 6 days) with no problem at all and this since 4 or 5 month. Then I'm suspicious about the max freq allowed.(some run at more than 250Mhz but i don't have test myself) They made publicity with the 180Mhz , with no USB available (that it's not in publicity). Someone at the ST Forum will ask the devs for more info about this. And if i kill a $30 board after 6month or more i don't care , 5 another
in reserve for my proto test ... he he .. So long my devs can continue and my lib grow up , I'm happy
Cheers. Theory is when we know everything but nothing work ... Practice is when everything work but no one know why ;) |
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