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Shoe Box Radio Upgrade, cool ideas wanted

Discussion in 'General Electronics Chat' started by Dragon Tamer, Feb 20, 2010.

  1. Dragon Tamer

    Dragon Tamer Member

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    Thank you very much, very specific. Also you are right about radio shack, they just don't sell the parts that they used to. Oh well, I just have to work around that fact.
     
  2. Mikebits

    Mikebits Well-Known Member

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    I have a couple questions.

    On the DS12C877, why is the MOT pin tied to the 2250 P3.2 pin? Just tie it low for Intel timing.

    Why are you using PSEN/ for your RTC IRQ/ pin? What is the other pin tied to IRQ?

    Why not tie RTC IRQ to DS2250 P3.2?

    Why are you using a 555 for your reset, won't an RC network suffice?
     
    Last edited: Mar 13, 2010
  3. Dragon Tamer

    Dragon Tamer Member

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    Like I've said before, I know almost nothing about uCs. However, I will answer your questions as logicaly as posible.
    First, the MOT pin was tied to the P3.2 pin because the data sheet said that both staes opperate differently. I didn't know which mode the 2250 would need.

    There is some confusion about the connectioon of the pins, that was my mistake. Let me clean the circuuit up and repost it.

    I suppose that an RC network could work, I only used a 555 because it was the first thing that came to mind.

    Do I at least get credit for trying? :D
     
  4. dave

    Dave New Member

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  5. Mikebits

    Mikebits Well-Known Member

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    Of course :)
    Tie MOT pin for Intel timing mode. Unless you have some special timing constraint on your reset pin, use a 33uf cap from 5v to RST pin.

    I suggest you obtain the old MCS-51 user manual. Try this link. Downloads / 8051 Ebooks and Tutorials / Intel MCS 51 (8051) User manual : 8051 Microcontroller Projects AVR PIC Projects Tutorials Ebooks Libraries codes
     
    Last edited: Mar 13, 2010
  6. Dragon Tamer

    Dragon Tamer Member

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    I was working on trying to complete the circuit for the uC and it came to me that I don't know how to make the interface circuit for the computer to program the micro-controller. I looked on google, that was even less help to me. The data sheet says that you can use an RS232 conroller to program it, or a paralell port (please excuse my spelling). The paralell port would be eiser to make, but it leaves less I/O pins open for the uC to interface with the iPod.

    Also, an analog question for anyone that can help. I would like to have a constant current source for the LED inticators in the circuit, but I can't find one for common cathode LED's.
     
  7. Space Varmint

    Space Varmint New Member

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    I have used the Intel 8255 which has 3 parallel ports. You can also use a 74hc138 decoder to select several 8 or 16 bit latches like this:
     

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  8. Dragon Tamer

    Dragon Tamer Member

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    I don't want to sound ungrateful, but is there an easier way? Could I attach a digital multiplexer or something to the input? The only reason I'm asking is that my computer does not have a serial port, just a parallel port (which is kind of weird). Unless the 74HC138 is similar to the 4028, in which case I have an abundance of them.

    I have the second attempt at me trying to make the circuit for my µC, I've attached the circuit below.

    I also have the pin out for the iPod connector but this is just what I found on Google, before you go making conclusions you may want to double check my results.

    Here they are:
    1) ground
    2) ground-AV
    3) R/audio out
    4) L/audio out
    5) R/audio in
    6) L/audio in
    7) not shown
    8) Video out
    9) not shown
    10) not shown
    11) Serial ground
    12) serial-TX
    13) serial-RX
    14) not shown
    15) ground-
    16) USB-ground
    17) not shown
    18) 3.3V- out
    19) FW 12V
    20) FW -12V
    21) sireal enable
    22) FW-TPA-Pos
    23) USB 5V
    24) FW-TPA-Pos
    25) USB data neg (-)
    26) FW-TPB-neg (-)
    27) USB data- pos
    28) FW-TPB-pos (+)
    29) FW ground
    30) FW ground (-)

    Here is a link to the website where I got the pin out.
     

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    Last edited: Mar 17, 2010
  9. audioguru

    audioguru Well-Known Member Most Helpful Member

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    My computer does not have a 30 pins connector. Why does yours have one and what is it for/labelled?
    Why are you feeding the signal to a computer when you have a micro-controller?
     
  10. Space Varmint

    Space Varmint New Member

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    Well, actually if you understand the term "embedded" as in embedded processor, you will find that the Pentium processor in your computer has Intel 8255's in it. That's what it uses for the parallel ports. But either is easy enough if you have bit level control. What sort of compiler are you using? I used to write device drivers for ring zero all the way up to XP but they put something new in Vista that keeps me out. Well I don't try anymore. Too busy doing other stuff. But if you can flip the bits on the parallel port than either will do. The other isn't hard. The decoder simply selects which latch will be active while the others tri-state their condition. If your processor is serially programmed then just use the pins from your PC's parallel port directly with no hardware interface. Should work fine.

    *You may need one 12 volt line for the VPP signal for the flash BIOS.
     
    Last edited: Mar 17, 2010
  11. Dragon Tamer

    Dragon Tamer Member

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    ... you lost me. I'm going to try to find the answers to some of the things you said, (I'm going to google everything, then ask my teacher if he understands) but I don't really know any of the answers for now.

    My computer does not have a 30 pin connector, the adapter for the iPod needs a 30 pin connector. I intend to have the micro-controller use this to work the iPod when certain conditions are met.
     
  12. Space Varmint

    Space Varmint New Member

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    Not sure which you mean? Embedded? Let me give you a bit of history to explain: (Oh, I forgot a processor. I started out on the Z80)

    The original IBM PC had in it as it's main components, these:

    a) 8088--processor & BIU (bus interface unit)
    b) 8259--interrupt controller
    c) 8255--parallel port controller
    d) NS16450--serial port controller
    e) 8253 real time clock
    f)--DMA controller
    g)--refresh controller for DRAM


    A couple may need explanation so here goes: The refresh controller is used to strobe (which is just a read operation) the SRAM because it needs a voltage to recharge the memory or after a minute or so the memory contents will disappear. The DMA (Direct Memory Access) controller is used to free up the processor by using what is known as a "bus master" operation. The processor can be busy doing something else instead of having to handle doing memory dumps to peripheral devices. So the processor sets up everything then it uses a couple of signals (DMA request / DMA acknowledge) so that say a disk drive can get data directly from the memory or vice-versa. Once the initialization sequence has been established the processor will tri-state it's outputs and give the DMA controller, control of the data and address buses. Upon completion the processor will resume control of both.

    So, starting after the development of the 80286 (first processor with protected mode) they began a line of products known as "embedded" processors. I believe the 80188 was the first. What it had that was different is, all of the controllers listed above were built into one package. A single chip! So now, all you needed to add was memory both volatile (DRAM) and non-volatile (PROM where they put the BIOS). That's it! You have a full blown computer. You could use SRAM (a little slower) in place of DRAM and maybe Flash if it was around in place of EPROM.

    Hope that cleared it up for you.
     
  13. Dragon Tamer

    Dragon Tamer Member

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    So what do you suggest I do for the DS2250? I also had the idea of, what if we could use some of the I/O pins for programing and then use them for controlling something in the circuit. I'm affraid of not having enough pins to control everything in the circuit. Am I being irrational? (I also need the uC to work the circuit with the remote)

    I have a question about a Bi-Fet op-amp. I have a couple, but I can never get them to work properly, is there a special way that your supposed to configure the circuit for them?
     
  14. Space Varmint

    Space Varmint New Member

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    OK Dragon. You need a programmer right? I think you better just buy one. Why don't you just use a PIC processor? You can get the PicKit2 for 50 bucks. Come on, join the crowd :D
     
  15. Dragon Tamer

    Dragon Tamer Member

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    No... being a rebel is too much fun. :p The real reason that I want to use the DS2250 is because I got it for free, and I haven't been able to use it. I figured that now would be the perfect time to use it. (fyi, I never follow the crowd. That's why I'm always on here and not with my freinds. :D)
     
  16. Dragon Tamer

    Dragon Tamer Member

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    Just a quick update, I finished making the power supply for the box. It's a thing of beauty. :) There were a few problems with the circuit that were promply corrected and now the circuit is working fine. I also made a "touch button" that triggers a PNP to work the trigger pin on the 556. I didn't know that I could do that. :D There are still a few things that need to be made for the power supply, the battery charger still needs to be installed, the battery monitor, the battery (notice the trend here). Once those are added, I'll remake the schematic and repost it. Maybe take a picture for you! :)
     
  17. Space Varmint

    Space Varmint New Member

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    You know why I suggested that I'm sure. You need a programmer. Now let's discuss the basics. What do you have to flip bit? Can you do it with your computer? In other words, do you have a program of some sort that will let you access ring zero for hardware control of the parallel or serial ports? If you do not, than you will need something that can. It is possible to do with dip switches but you have to input each address and it is a pain. So what you got to work with first of all?
     
  18. Dragon Tamer

    Dragon Tamer Member

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    Couldn't I just make a circuit using transistors or FET's that will enable when the port is pluged in and switch to an output when the connection is broken? What if I tried to use a USB bort (which I have plenty of), could I use the circuit like the one in the first image to program the DS2250? Also, what if I made the circuit like in the second picture? (I think that this one may need an RS232 addaptor for the IC) but either way, this would free up a lot of the ports for the uC so it can do its job properly.
     

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    Last edited: Mar 23, 2010
  19. Space Varmint

    Space Varmint New Member

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    Well I think either. The first looks better. What sort of software do you have that will allow you to send data through the USB port? Please tell me this. I think I would lie a copy if possible.
     
  20. flat5

    flat5 Member

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    SV, thanks for the clear talk in post #111. I may have learned a thing or two :)
     
  21. Dragon Tamer

    Dragon Tamer Member

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    I'm not a hundred percent sure of what software I should use, I was hoping that maybe you could tell me. (after all your the expert :)) The only thing that I can tell you for sure is that I'm running windows (I hate macs). There were some firmware downloads on some of the sites that I came across, but I'm not sure if I want to downlaod them just yet. I do have some software on my home computer, I will tell you what it is when I get the chance.
     

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