Would it be possible to use this chip for making a computer with 12 bit color?

Comments

• Mike Green Posts: 23,101

  2007-06-13 21:46 edited 2007-06-13 21:46

  Bob,
  First of all, what do you mean by 12-bit? For the video, do you mean 4 bits per RGB color (or 16 colors per pixel)? For the audio, do you mean 6 bits per channel for stereo or 12 bits for a monaural channel? In both cases you will have problems with buffer memory.
  
  Have a look at what Andre has done with the Hydra SRAM expansion card. This adds 512K of high speed memory that the Propeller can manipulate with only a few I/O pins. With a simple redesign (maybe using the Hydra Xtreme Memory card as a development platform) you could directly drive a 12 bit DAC from one SRAM and a triple 4-bit flash DAC from another SRAM, each under control of the Propeller for basic timing. That would eliminate the need to use all the Propeller's I/O pins to control the memory and the timing.
  
  What do you mean by internet port? There are a variety of devices that include an embedded processor along with an ethernet port and handle all the protocols. They talk via a logic level serial port to the host. You can also use an ethernet controller chip (of which there are several), but you'd have to do the protocol handling in the Propeller code ... a complex and large undertaking.
• Bob the Builder on a C64 Posts: 112

  2007-06-14 00:53 edited 2007-06-14 00:53

  for 12 bit video, I mean 4 bits per RGB color, and a total of 4096 colors.
  
  For 12 bit sound I mean 12 bit monaural channel.
  
  As for internet, I mean the ability to use DSL with the chip
  
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• Harrison. Posts: 484

  2007-06-14 01:27 edited 2007-06-14 01:27

  I can't say much for the video and audio stuff, but I can say that your statement about wanting internet is still a bit too vague. What exactly do you want the chip to do on the 'internet'? Do you want to browse the web or what?
  
  Ethernet is not easy and requires understanding of the underlying protocols (tcp/ip, udp, arp, etc), along with understanding of upper level communication protocols such as http. Not to mention you will have a difficult time handling stuff on the internet with the limited memory on most single chip processors such as the Propeller.
  
  Harrison
• Bob the Builder on a C64 Posts: 112

  2007-06-14 02:38 edited 2007-06-14 02:38

  By "internet" I mean browsing the internet on the propellor, but I might just have to wait till the next propellor chip comes out inorder to surf the internet at a "decent" speed.
  
  For color, I just want to know specific chips I could use to give it 12-bit color to video output, same with sound just to the audio output.
  
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• Mike Green Posts: 23,101

  2007-06-14 02:46 edited 2007-06-14 02:46

  Well, you can certainly use a 12 bit serial (probably SPI) DAC for the audio. The MAX5531 is one example of a 12-bit SPI DAC that can operate from a 3.3V supply. Check Maxim's website for others. There are plenty ... with all kinds of featues.
  
  For the video, you will need some kind of external screen buffer. Again, use the Hydra Xtreme Memory Card for an example of how it can be done. Theoretically you could use two cogs in sync to produce a VGA signal with 4 bits for each color since the video generators are just fancy shift registers that can shift out 2 bits per color per cog. The problem will be keeping them "fed" with data. Unless you want high resolution, you might be able to do it using the Xtreme Memory Card. You'll need three bytes per two pixels, possibly four.
  
  I can't recommend a 4-bit video DAC to use. You'll need 3 of them. You're already tying up a lot of I/O pins. I still think you'd be better off with some kind of external video controller.
• Harrison. Posts: 484

  2007-06-14 03:34 edited 2007-06-14 03:34

  Your best bet for 'browsing' the internet on the Propeller is to download entire html pages and strip out the html tags on the fly (might be complicated depending on how you approach it). You will then end up with a text based browser which is probably the best you can do without extensive and complex programming.
  
  You will need to tackle the ethernet stuff in little steps. First get a working tcp connection to a web server, then proceed onto doing other stuff such as querying the server and processing the response text.
• potatohead Posts: 10,254

  2007-06-14 05:12 edited 2007-06-14 05:12

  They did something like this for 8 bit computers. The thing would reload pages, then display the relevant portion to avoid in memory buffering of text.
• Bob the Builder on a C64 Posts: 112

  2007-06-14 12:49 edited 2007-06-14 12:49

  Thanks, but I don't want to generate color in software, only in hardware... So would the 3 4 bit DAC converters work for that? or would I have to wire alot of resistors?
  
  
  
  
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• Mike Green Posts: 23,101

  2007-06-14 13:17 edited 2007-06-14 13:17

  Bob,
  Generating VGA in hardware requires a lot of hardware. The DACs only do the conversion from digital to analog. All the timing and formatting has to be done somewhere and you need buffer memory and all the logic to control it. You could theoretically connect a PC VGA display card to a Propeller, but it would require a lot of I/O pins. If you could find an old VGA card for an embedded PC, like with a PC/104 bus, you might be able to cobble together an interface for it. You'd have to write your own drivers.
• Bob the Builder on a C64 Posts: 112

  2007-06-14 17:28 edited 2007-06-14 17:28

  great! I think I'll go with finding an old VGA graphics card on ebay. I think that if I end up with decent results, I'll show it on the propellor forums, but I won't be doing this for a while.
  
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• Mike Green Posts: 23,101

  2007-06-14 17:51 edited 2007-06-14 17:51

  A couple of 8 bit latches would let you have a 24-bit address bus and an 8 bit data bus with maybe 12-14 I/O pins. If you're interested, you could use the same arrangement for other PC I/O cards as well using a sort of bus extender chassis.
• Bob the Builder on a C64 Posts: 112

  2007-06-14 21:15 edited 2007-06-14 21:15

  Can you give me some pics of what these look like, or of·what the connections would look like?
  
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• Bob the Builder on a C64 Posts: 112

  2007-06-15 02:18 edited 2007-06-15 02:18

  I think this propellor chip isn't powerful enough to have a built in OS into it, I think that by the time I have a program done(1 year)The chip will be out, and I'll use it for this.
  
  Has anyone made a Java program for the Hydra? As in, a program that lets you program in java on the propellor?
  
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