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Serial programmer difficulty. Need help! — Parallax Forums

Serial programmer difficulty. Need help!

StratosStratos Posts: 15
edited 2007-10-13 22:58 in Propeller 1
·Hi all. New to the propeller, but just purchased·the prop. proto board·and soldered a serial programmer according to the parallax schematics. The propeler tool recognizes the IC but when I try to program the chip it gets stuck on downloading the ram !· Any suggestions please ?··

Comments

  • Ken PetersonKen Peterson Posts: 806
    edited 2007-10-13 15:06
    I have a demo board that does that occasionally with the prop plug. Sometimes it works great, other times I have to try 5 or 6 times before it successfully downloads.

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    The more I know, the more I know I don't know.· Is this what they call Wisdom?
  • Mike GreenMike Green Posts: 23,101
    edited 2007-10-13 15:06
    The fact that the Propeller Tool recognizes the chip indicates that your basic setup is ok. The download process is very dependent on the Propeller Tool and the Propeller responding promptly to each other. If you're using a USB to serial adapter under Windows, you may need to adjust some buffering parameters for the adapter. There's a downloadable document you can get from the Propeller webpage on fixing problems with downloading and that will help you.

    If you need more or better suggestions, you will have to give more information about your setup.
  • RaymanRayman Posts: 14,791
    edited 2007-10-13 15:12
    (I'll say it again, even though deSilva thinks I did something wrong [noparse]:)[/noparse]

    I made the 2-transistor circuit exactly as described in the datasheet and it didn't work right using a 6' cable. Then, what I put it directly to the back of the computer (without a cable) it worked. Eventually found that adding a capacitor between RES and Vss made it work with the cable.
  • StratosStratos Posts: 15
    edited 2007-10-13 15:17
    ·Thanks Mike. I'll try to adjust some properies on my comp BIOS or device manager if possible but here is my config anyway: I am using my computer's serial port running windows xp SP3. I've used the schematic that uses two transistors to translate voltage levels for the RS232 requirment. There is no mouse or keyboard attatched to the proto board, just a few resistors that make the 3 bit DAC for my video out connector. My intention is to see what the propeller can do on·NTSC video. ·
  • Ken PetersonKen Peterson Posts: 806
    edited 2007-10-13 15:26
    With the circuit shown in the diagram, the voltages aren't really within the spec for RS-232. Even if you use the recommended +/-12 V signals, RS-232 isn't specified to work over distances of a few feet.

    If you have a scope handy, you can see if your reset line is getting toggled during your program download. I was going to suggest using that prop-based oscilloscope, but if you are having trouble establishing a link to the PC than that option is not available.

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    The more I know, the more I know I don't know.· Is this what they call Wisdom?
  • StratosStratos Posts: 15
    edited 2007-10-13 15:37
    Thanks all. Problem was solved!!! Back in 1994 had similar problem when dealing with serial ports... so just remembered, went to device manager, changed the flow control from none to Xon.xoff , buffers to zero and baud rate to 2400 and boom, everything works perfectly !
  • Mike GreenMike Green Posts: 23,101
    edited 2007-10-13 15:45
    Ken is right about the voltages in this 2 transistor circuit being marginal for many serial ports, although I'd disagree about the distances achievable with "real" RS232 voltage levels. You'd be much better off with a "real" RS232 converter like the MAX3232. Look at the schematic for the PropStick for an example. There may also be a problem with your 6' cable and noise coupling from signal to signal. Try another cable.
  • StratosStratos Posts: 15
    edited 2007-10-13 16:09
    · That is correct. This is not true RS232 translation and·I had my max3222 ready·but I played around for a few mins now, and·it seems that the serial buffer makes all the difference.·With zero buffering·I was getting·60 percent success·in programming the IC. When I disabled the buffer·completely·got 100% successful. People having trouble should try it. Thanks you all.·
  • RaymanRayman Posts: 14,791
    edited 2007-10-13 17:48
    Does it really matter what the settings are in "Device Manager"? I thought that the Propeller Tool would override the defaults for it's own settings...
  • StratosStratos Posts: 15
    edited 2007-10-13 22:58
    ·Yes it will...but as far as I can tell·the propeller tool can't modify settings such as enabling , disabling serial buffers nor the amount of buffering·etc.·Speed, parity flow conrtol·etc... I bet it can.·I believe that even people that are using the propclip/prop plug and having problems with programming (sometimes IC won't program) will benefit if thay just disable the serial buffer. I couldn't program it·at all! As soon as I disabled the buffer, there has been not even once that the IC didn't program successfully. Just have to try.
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